Science N Techno ::

Measuring Hospital Efficiency: A Comparison of Two Approaches

2010-01-03T18:35:00.000-08:00

Objective. To compare the results of scoring hospital efficiency by means of two new types of frontier models, Data Envelopment Analysis (DEA) and stochastic frontier regression (SFR).

Study Setting. Financial records of Florida acute care hospitals in continuous operation over the period 1982-1993.

Study Design. Comparable DEA and SFR models are specified, and these models are then estimated to obtain the efficiency indexes yielded by each. The empirical results are subsequently examined to ascertain the extent to which they serve the needs of hospital policymakers.

Data Collection. A longitudinal or panel data set is assembled, and a common set of output, input, and cost indicators is constructed to support the estimation of comparable DEA and SFR models.

Principal Findings. DEA and SFR models yield convergent evidence about hospital efficiency at the industry level, but divergent portraits of the individual characteristics of the most and least efficient facilities.

Conclusions. Hospital policymakers should not be indifferent to the choice of the frontier model used to score efficiency relationships. They may be well advised to wait until additional research clarifies reasons why DEA and SFR models yield divergent results before they introduce these methods into the policy process.

Key Words. Hospital efficiency, Data Envelopment Analysis, stochastic frontier regression, hospital cost containment

Until recently, the efficiency of hospitals has been measured by estimating cost or production functions by means of ordinary regression methods. Cost studies, for instance, typically regressed operating expenses against various measures of hospital "output," input prices, and control variables such as case mix of the patient population to draw inferences about efficiency differentials across hospitals (Cowing, Holtmann, and Powers 1983). Although these regression studies produced many useful insights, they were unavoidably subject to the limitation that the estimated equation represented the average as opposed to the best-practice cost-output relationship. The error term in such regressions has a mean of zero, so deviations from the estimated "line" (hyperplane) are not only as likely to raise costs as reduce them, but are assumed to be entirely attributable to chance factors. It is intuitively clear that some observations below the regression "line" in cost equations are systematically more efficient in the sense that, for a given set of factor prices and patient characteristics, they produce more output per unit of input. However, ordinary regression methods cannot distinguish between these systematic variations and those truly due to statistical noise. In an industry where inefficiencies are thought to be widespread, this methodological gap seriously limits the use of such statistical inferences for policy purposes.

Recent years have witnessed technical developments in the field of management science and econometrics that hold out the promise of enabling analysts to identify best-practice output-input (cost) relationships as well as to gauge how much efficiency levels of given decision-making units or providers deviate from these frontier values (Bauer 1990). One of these developments is Data Envelopment Analysis (DEA), a nonparametric programming technique that pieces together an efficiency frontier by maximizing (a seriatim) the weighted output/input (cost) ratio of each provider, subject to the condition that this ratio can equal, but never exceed, unity for any other provider in the data set (Charnes, Cooper, and Rhodes 1978). DEA then yields several measures of the relative distance of any provider's efficiency ratio from the piecewise linear frontier, the most common being the proportional reduction in input or cost levels that could be achieved were the provider delivering services in the most efficient manner po ssible. Another was the development of stochastic frontier regression (SFR) methods. Unlike its classical OLS counterpart, SFR models the error term in two parts, one reflecting systematic deviations from a frontier (cost or output) level and the other from more conventional statistical noise (Aigner, Knox Lovell, and Schmidt 1977). SFR uses this composable error, as it is called, to estimate the overall efficiency level across any sample of providers and then, in what may be characterized as a second step, computes efficiency deviations of each sample observation from the industry frontier by taking the expected value of the disturbance of each observation, conditional on the estimated parameters of the underlying distribution of the composable error (Jondrow et al. 1982; Greene 1992). Like DEA, these SFR provider-specific efficiency values are also cast as the proportional difference between the costs (output) of any provider and the frontier level of costs (output).

Not surprisingly, the efficiency vectors yielded by DEA and SFR techniques find ready uses by policymakers, nowhere more so than in the hospital sector. Indicators of the relative efficiency of hospitals are needed to gauge whether hospital cost-containment efforts are succeeding; they are also needed to evaluate the effect of more extensive managed care arrangements in local healthcare markets and to prepare "report cards" and other quality assessments of hospital service delivery. Such indicators may also have a prescriptive role to play in establishing criteria for selective contracting purposes and in pegging reimbursement levels in hospital rate-setting programs; see Batavia et al. (1993), Hadley and Zuckerman (1994), and Newhouse (1994) for differing views on these potential uses. Yet, whether frontier methods actually live up to their policy promise is untested at the moment. The recent literature includes a number of DEA hospital applications but only one published SFR study. [1] The knowledge base m ust be expanded before we can judge if, and how well, frontier methods serve the needs of hospital policymakers.

http://findarticles.com/p/articles/mi_m4149/is_6_34/ai_59629773/

Flu Robot Displayed in Tokyo

2009-10-22T17:53:00.001-07:00

A robot that displays symptoms of swine flu was among the exhibits at a Tokyo trade fair. The robot sweats, moans and cries. It's designed to help health care workers diagnose and treat the flu. (Oct 22)

Planning for tomorrow

2009-10-07T20:51:00.000-07:00

By Tod Moore, RCDD

It takes teamwork to build the modern OR

It takes teamwork to build the modern OR

One of the greatest challenges faced by OR managers, hospital administrators and facility design teams is determining which technologies should be deployed on the first day of a facility’s opening, which technologies should be prepared for the future and how they should all fit together. The key to successfully working through these crucial issues is early planning by the entire design team.

OR technology planning

From the medical equipment perspective, knowing which ORs will be configured for which type of procedure will determine the equipment and configuration. But, as it relates to the audiovisual and information technology systems, it is a little more difficult to nail down.

Granted, almost all medical equipment today requires connectivity to the data network, and that is primarily an infrastructure-related issue that is accomplished through coordination with the medical equipment planner, architect and the technology consultant. However, as it relates to what type of communication systems, displays and applications to use, consideration must be given to how procedures are performed, organizational and operational efficiencies, flexibility and due diligence to determine the return on investment for various systems.

First steps in this process begin at the OR stakeholders meeting with the facility’s information technology department, the technology consultant and the architect to plot the strategic plan for OR operation and organization in regard to technology systems. From this visioning process, clear guidelines, systems selection and cost models should be determined. The results of this process become a road map for technology deployment for the project.

The resulting road map is not a static document. Due to the nature of the design and construction process, combined with the fast-paced, changing world of communication technologies, it must be a flexible plan that allows for adaptation throughout the life of the project. One key to success for any OR technology deployment, or any health care technology deployment for that matter, is future-thinking for infrastructure flexibility, adaptability and growth.

Perhaps various systems are desired that will not be deployed when the OR opens but may be installed several years down the road. The better the team can anticipate future needs and provide for a more plug-and-play infrastructure to accommodate future deployments, the lower the cost, time and inconvenience associated with new systems integration.

The integrated OR

One emerging technological trend is the integrated or “context aware” OR, an environment that links changes in the OR environment with the computer systems in use, which are otherwise static. This environment is achieved with systems that take advantage of technologies such as radio-frequency identification (RFID) and integrates them with other systems such as telemetry, medical vitals, electronic medical records (EMR), picture archiving and communications systems (PACS), and other software applications to provide a real-time, interactive monitoring platform.

When using RFID on staff, surgical tools, medications and more, movement of these items can be monitored and OR staff can be notified that a given item that was scheduled as part of the procedure has not been used, like an early warning system. RFID can provide essential, location-based information throughout the entire procedure, including who entered and exited the OR or what surgical tools were used, for historical record keeping and procedure review for educational purposes.

All this information can be displayed on the patient dashboard for the surgeon and the OR staff. Systems such as the LiveData OR Dashboard™ from LiveData Inc. (www.livedata.com), Cambridge, Mass., captures, synthesizes and automatically displays essential patient information in real-time throughout the patient procedure.

Robotics in the OR

Futuristic technologies that are becoming more and more of a reality in the operating room, although in limited numbers, are robotic surgical tools.

These medical curiosities range from surgical tools and medication dispensers to state-of-the-art remote surgical procedure robots, such as the da Vinci® Surgical System by Intuitive Surgical Inc. (www.intuitivesurgical.com), Sunnyvale, Calif., which allows a surgeon to perform surgery from outside the OR, or even in another city or country. As of 2000, the da Vinci system has been cleared by the Food and Drug Administration (FDA) for general laparoscopic surgery and, since then, the FDA cleared the da Vinci surgical system for thoracoscopic (chest) surgery for cardiac procedures performed with adjunctive incisions and urologic and gynecologic procedures.

Many medical futurists believe that one way to improve efficiency in the OR and help combat the nurse shortages will be to utilize more robotic surgical devices. Imagine freeing available staff for other vital patient-related tasks and replacing the scrub nurse or the circulating nurse with a robotic system that never tires and is always available, such as the Penelope™ Surgical Instrument Server (SIS) from Robotic Systems & Technologies Inc. (www.roboticsystech.com), Bronx, N.Y.

Combine robotics with a truly context aware OR, and the possibilities for unmanned surgical procedures are possible. An example of this is the unmanned OR lab at the Scientific Research Institute (SRI) (www.sri.com) in Menlo Park, Calif. Presently focusing on surgical procedures for soldiers in the battlefield to conduct unmanned medical treatment, this technology and the use of the “trauma pod” can stabilize injured soldiers within minutes after a trauma, and administer life-saving medical and surgical care prior to evacuation and during transport. This innovative technology also has the potential to be used in civilian hospitals when trauma centers are too far away to save a patient’s life.

Remote monitoring

In addition to remote surgical procedures is remote monitoring. With tremendous advances in telemedicine, the ability to accurately view and remotely interact real-time with a surgical team is here today. High-definition video combined with new camera technology has created the telepresence environment, allowing for accurate remote consultative surgical procedures, as well as detailed medical educational tools.

Telepresence solutions such as the MedPresence conference room being used at St. Joseph’s Hospital and Medical Center’s Barrow Neurological Institute in Phoenix allows physicians and students to remotely observe surgeries being performed in real-time from the physician’s office or the classroom. Participants feel as if they are in the operating room with the ability to view all aspects of a given operation. The benefits of the solutions like the MedPresence Surgical Training Theatre by Human Productivity Lab (www.humanproductivitylab.com), Ashburn, Va., are significant in all aspects of the medical-surgical field through increased productivity, reduced travel and improved distance learning. This leads to dramatic return on investment (ROI) for medical organizations. For instance, a physician who is required to be in the OR with his or her patient throughout a surgical procedure, although not physically performing the procedure, can now be face-to-face in surgery from a few doors down in his or her own office space. This allows the physician to be productive on other tasks while still being involved in the surgery. By the same token, high-dollar procedures that are performed at only three or four institutions throughout the world can be observed by a wide network of medical colleagues, surgical residents and medical students. These real-time participants can take advantage of the knowledge to be gained from renowned experts using emerging surgical techniques without traveling long distances.

Practice makes perfect

In another trend, preoperative planning and surgical rehearsal of complex procedures in an interactive visualization environment can be created to allow the production of 3-D surgical planning data sets. Image review and analysis tools allow the surgical review of computed tomography, magnetic resonance imaging and angiographic examinations in an interactive 2-D and 3-D environment.

Surgery simulators can be classified into three categories. The first-generation simulators display only the anatomy, in particular the geometry of the structures involved in a surgical procedure. With this, the user can essentially navigate within a virtual representation of the patient, with limited detail.

A number of these simulators have been developed in recent years and are available today. These systems are generally used as diagnostic tools, and also to assist with surgery planning, but are limited in their complexity.

Second-generation simulators not only include the geometric modeling of the body anatomy, but also the modeling of the physical properties of the living tissues. This provides for realistic interactions between surgical instruments and the actual tissues. A few of these systems are available today, including such surgical simulators as LAP Mentor™ by Simbionix™ USA (www.simbionix.com), Cleveland, or the ProMIS™ by Haptica Inc. (www.haptica.com), Boston.

Third-generation simulators combine anatomical, physical and physiological modeling. There is a greater degree of complexity with these models because they are combining the physiological and physical properties of the patient. Some third-generation models exist, but no commercially available product is currently on the market.

Breakthroughs in lighting

Finally, there have been different ways of focusing light in the OR, different ways of directing the light or creating a spot, but for over 70 years the light source itself has been the halogen bulb. This light source is known for its high-quality bright light, but not for its efficiency in terms of lamp life or heat.

Advanced surgical lighting uses light-emitting diode (LED) technology that utilizes both white and color LEDs to create a very high level of almost shadow-free illumination.

The most important features in surgical lighting—intensity, color temperature, heat control, shadow control, maneuverability and flexibility—are inherent in this technology. Surgeons can even use voice commands to adjust the intensity or color of the light.

Detailed due diligence

Determining which systems to consider and deploying them in the OR is a daunting process that requires due diligence by the design team as it relates to process, culture, services and cost.

Gathering the appropriate stakeholders and technical experts to look at strategic plans, ROI, future trends and facility impacts are crucial to successful OR suite design and implementation.

Tod Moore, RCDD, is principal of technology consulting at Sparling, Seattle. His e-mail address is tomoore@sparling.com.

This article 1st appeared in the April 2008 issue of HHN Magazine.

How the Predator UAV Works - Under the Hood

2009-10-07T20:43:00.000-07:00

Under the Hood

The Predator UAV is a medium-altitude, long-range aircraft that operates much like any other small plane.

Photo courtesy U.S. Air Force
An airman works on the Predator's Rotax 914 engine.

A Rotax 914, four-cylinder, four-stroke, 101-horsepower engine, the same engine type commonly used on snowmobiles, turns the main drive shaft. The drive shaft rotates the Predator's two-blade, variable-pitch pusher propeller. The rear-mounted propeller provides both drive and lift. The remote pilot can alter the pitch of the blades to increase or decrease the altitude of the plane and reach speeds of up to 135 mph (120 kts). There is additional lift provided by the aircraft's 48.7-foot (14.8-meter) wingspan, allowing the Predator to reach altitudes of up to 25,000 feet (7,620 meters). The slender fuselage and inverted-V tails help the aircraft with stability, and a single rudder housed beneath the propeller steers the craft.

The fuselage of the Predator is a mixture of carbon and quartz fibers blended in a composite with Kevlar. Underneath the fuselage, the airframe is supported by a Nomex, foam and wood laminate that is pressed together in layers. Between each layer of laminate, a sturdy fabric is sandwiched in to provide insulation to internal components. The rib work of the structure is built from a carbon/glass fiber tape and aluminum. The sensor housing and wheels are also aluminum.

The edges of the wings are titanium and are dotted with microscopic weeping holes that allow an ethylene glycol solution to seep out of internal reservoirs and breakdown ice that forms on the wings during flight.

The Predator UAV uses run-of-the-mill mechanical systems. A 3-kilowatt starter/alternator supplies the craft's electronics with power; this is supplemented with auxiliary battery power. Forward and aft fuel tanks house rubberized fuel bladders that are easy to fill through gas caps located at the top of the fuselage. An operator starts the engine by attaching the umbilical cord of a Starter/Ground Power Cart to the aircraft's starter-control connector, located in the ground panel on the outside of the plane. An operator stops the engine by hitting a kill switch just behind one of the wings on the side of the plane.

For the Engine

The Predator's two fuel tanks combined carry up to 600 pounds of 95-octane to 100-octane reciprocating aircraft engine fuel.

The Predator uses 7.6 liters of standard motor oil for lubrication.

In addition to venting, conventional automotive antifreeze is used to cool the engine.

Two 8-pound, 14-amp-hour Ni-Cad battery packs are housed in the fuselage for backup power in case the engine or alternator fails.

Making more milk - Breastfeeding.

2009-07-01T19:33:00.000-07:00

When women get together and start swapping stories of the days
when their babies were small and the subject of breastfeeding
comes up, chances are at least one woman will say, “I couldn’t
make enough (or my doctor said I didn’t have enough) milk, so I
had to quit nursing.” If the subject changes quickly, no one gets to
hear the sadness behind those words or the questions that could be
asked: “What happened? Did anyone give you a reason?” That’s
where this book comes in. When there’s another baby on the hori-
zon, that same woman will grab this book right out of your hand.
She wants answers, and The Breastfeeding Mother’s Guide to Making
More Milk has them. She needs to know she didn’t fail; the prob-
lem was that the answers weren’t there for her before. And there is
plenty she can do to make more milk for the next baby.
Breastfeeding problems of one sort or another have been
around forever, but good help for the complicated problems is still
evolving. Many doctors, nurses, and even midwives haven’t yet
heard of all the advances in the ﬁ eld of lactation, so women are still
being told they can’t make more milk or shouldn’t even consider
breastfeeding at all. One example close to my heart is how moth-
ers of babies with Down syndrome are often discouraged from
breastfeeding. When I gave birth to Stephen eighteen years ago,
his pediatrician thought I was being “heroic” for sticking with it
through four long weeks of weight los s before he turned the corner
and learned how to suck without hurting me. Until our culture is
convinced that breastfeeding and breast milk make a difference, it
is likely that this attitude wil l continue.
The ﬁ rst wave of breastfeeding help came from the founding
mothers of La Leche League in 1956. The second wave, which
resulted in the ﬁ eld of lactation science, began with passionate La
Leche League Leaders who helped one mother and then another
and then another, moving past the “easy” cases to the ones that
needed more time and attention, more research, and more persis-
tence. These are the cases you’ll read about in this book, and you’ll
see the work of these pioneers listed in the References.
Now we see the third wave of breastfeeding help: the creden-
tialed lactation consultants whose numbers have mushroomed,
medical researchers and practitioners who are advancing the ﬁ eld,
and the Academy of Breastfeeding Medicine as a formal organiza-
tion. The Breastfeeding Mother’s Guide to Making More Milk com-
bines all these resources for mothers who may otherwise never
ﬁ nd their way past the hurdles of low self-conﬁ dence and inexpe-
rienced helpers. As the ﬁ eld of lactation has come into its own as
a specialty, more and more of the previously “hopeless” cases have
been successfully addressed and remedied, many of them com-
pletely, and many mothers, no longer hopeless, are able to achieve
a full milk supply for their babies. The ones that don’t get a full
supply usual ly exper ience enough of an improvement to make the
effort well worthwhile.
Whatever the circumstances are, or whatever the root problem,
you can ﬁ nd your situation in this book and, detective-style and
systematically, alone or with support from your health care profes-
sionals, make the changes necessary to turn the problem around.
This book shows us how almost anyone can make more milk.

Historical Perspective - Immune System

2009-06-01T21:33:00.000-07:00

The discipline of immunology grew out of the observation
that individuals who had recovered from certain infectious
diseases were thereafter protected from the disease. The
Latin term immunis, meaning “exempt,” is the source of the
English word immunity, meaning the state of protection
from infectious disease.
Perhaps the earliest written reference to the phenomenon
of immunity can be traced back to Thucydides, the great his-
torian of the Peloponnesian War. In describing a plague in
Athens, he wrote in 430 BC that only those who had recov-
ered from the plague could nurse the sick because they
would not contract the disease a second time.Although early
societies recognized the phenomenon of immunity, almost
two thousand years passed before the concept was success-
fully converted into medically effective practice.
The first recorded attempts to induce immunity deliber-
ately were performed by the Chinese and Turks in the fif-
teenth century. Various reports suggest that the dried crusts
derived from smallpox pustules were either inhaled into the
nostrils or inserted into small cuts in the skin (a technique
called variolation). In 1718, Lady Mary Wortley Montagu, the
wife of the British ambassador to Constantinople, observed
the positive effects of variolation on the native population
and had the technique performed on her own children. The
method was significantly improved by the English physician
Edward Jenner, in 1798. Intrigued by the fact that milkmaids
who had contracted the mild disease cowpox were subse-
quently immune to smallpox, which is a disfiguring and of-
ten fatal disease, Jenner reasoned that introducing fluid from
a cowpox pustule into people (i.e., inoculating them) might
protect them from smallpox. To test this idea, he inoculated
an eight-year-old boy with fluid from a cowpox pustule and
later intentionally infected the child with smallpox. As pre-
dicted, the child did not develop smallpox.
Jenner’s technique of inoculating with cowpox to protect
against smallpox spread quickly throughout Europe. How-
ever, for many reasons, including a lack of obvious disease
targets and knowledge of their causes, it was nearly a hun-
dred years before this technique was applied to other dis-
eases. As so often happens in science, serendipity in
combination with astute observation led to the next major
advance in immunology, the induction of immunity to
cholera. Louis Pasteur had succeeded in growing the bac-
terium thought to cause fowl cholera in culture and then had
shown that chickens injected with the cultured bacterium de-
veloped cholera.After returning from a summer vacation, he
injected some chickens with an old culture. The chickens be-
came ill, but, to Pasteur’s surprise, they recovered. Pasteur
then grew a fresh culture of the bacterium with the intention
of injecting it into some fresh chickens. But, as the story goes,
his supply of chickens was limited, and therefore he used the
previously injected chickens.Again to his surprise, the chick-
ens were completely protected from the disease. Pasteur
hypothesized and proved that aging had weakened the viru-
lence of the pathogen and that such an attenuated strain
might be administered to protect against the disease. He
called this attenuated strain a vaccine (from the Latin vacca,
meaning “cow”), in honor of Jenner’s work with cowpox
inoculation.
Pasteur extended these findings to other diseases, demon-
strating that it was possible to attenuate, or weaken, a
pathogen and administer the attenuated strain as a vaccine.
In a now classic experiment at Pouilly-le-Fort in 1881, Pas-
teur first vaccinated one group of sheep with heat-attenuated
anthrax bacillus (Bacillus anthracis); he then challenged the
vaccinated sheep and some unvaccinated sheep with a viru-
lent culture of the bacillus.All the vaccinated sheep lived, and
all the unvaccinated animals died. These experiments
marked the beginnings of the discipline of immunology. In
1885, Pasteur administered his first vaccine to a human, a
young boy who had been bitten repeatedly by a rabid dog
(Figure 1-1). The boy, Joseph Meister, was inoculated with a
series of attenuated rabies virus preparations. He lived and
later became a custodian at the Pasteur Institute.

New device could track tumor's growth

2009-05-20T22:59:00.000-07:00

Surgical removal of a tissue sample is now the standard for diagnosing cancer. Such procedures, known as biopsies, are accurate but only offer a snapshot of the tumor at a single moment in time.

Monitoring a tumor for weeks or months after the biopsy, tracking its growth and how it responds to treatment, would be much more valuable, says Michael Cima, MIT professor of materials science and engineering, who has developed the first implantable device that can do just that.

Cima and his colleagues recently reported that their device successfully tracked a tumor marker in mice for one month. The work is described in a paper published online in the journal Biosensors & Bioelectronics in April.

Such implants could one day provide up-to-the-minute information about what a tumor is doing - whether it is growing or shrinking, how it's responding to treatment, and whether it has metastasized or is about to do so.

"What this does is basically take the lab and put it in the patient," said Cima, who is also an investigator at the David H. Koch Institute for Integrative Cancer Research at MIT.

The devices, which could be implanted at the time of biopsy, could also be tailored to monitor chemotherapy agents, allowing doctors to determine whether cancer drugs are reaching the tumors. They can also be designed to measure pH (acidity) or oxygen levels, which reveal tumor metabolism and how it is responding to therapy.

With current tools for detecting whether a tumor has spread, such as biopsy, by the time you have test results it's too late to prevent metastasis, said Cima.

"This is one of the tools we're going to need if we're going to turn cancer from a death sentence to a manageable disease," he said.

In the Biosensors & Bioelectronics study, human tumors were transplanted into the mice, and the researchers then used the implants to track levels of human chorionic gonadotropin, a hormone produced by human tumor cells.

The cylindrical, 5-millimeter implant contains magnetic nanoparticles coated with antibodies specific to the target molecules. Target molecules enter the implant through a semipermeable membrane, bind to the particles and cause them to clump together. That clumping can be detected by MRI (magnetic resonance imaging).

The device is made of a polymer called polyethylene, which is commonly used in orthopedic implants. The semipermeable membrane, which allows target molecules to enter but keeps the magnetic nanoparticles trapped inside, is made of polycarbonate, a compound used in many plastics.

Cima said he believes an implant to test for pH levels could be commercially available in a few years, followed by devices to test for complex chemicals such as hormones and drugs.

HIV drugs from plants

2009-05-19T22:55:00.000-07:00

A research team at Örebro University in Sweden has succeeded in changing the genes in plants so they can function as a vaccine against HIV.

Through gene modification the plants have acquired the capacity to produce a protein that is part of the virus, and the project has taken a giant step forward in that mice that have been fed the plants have reacted and formed antibodies against the protein. The findings are presented in a new academic dissertation at the university.

To produce drugs with the help of plants is a rapidly growing research field that offers new potential to combat diseases. At Örebro University researchers have the goal of developing inexpensive and safe protection against HIV, in the form of plants that contain a vaccine against the virus and can be cultivated all over the world. If they succeed, it will be difficult to exaggerate the significance of this for millions of people around the world, not least in the poorest countries.

"A major problem with the HIV virus is that it mutates rapidly and therefore exists in several different variants. In other words, it's not possible to create an effective vaccine that is based on the entire virus. Moreover, this would be far too risky. Instead, we have selected a protein, p24, that exists in all HIV viruses and looks roughly the same in the various virus lines," says Ingrid Lindh, author of the dissertation.

To get plants to produce the p24 protein, the gene that underlies the process must be a part of their own genetic make-up, but since it's impossible to transfer the gene directly from the virus to the plant, the researchers had to take a detour. This was done by first placing the gene into a bacterium that could then transmit it to the plants. The attempt succeeded; the plants produced p24 and also passed on this ability to their offspring.

In the next phase, mice were fed with the p24 plants, and these trials also proved to be successful. The mice's immune defense reacted just as the researchers had hoped, producing antibodies against the protein. In other words, this functioned as a vaccine. This raises hopes that a similar reaction in humans would make them immune to HIV.

"It is highly probable that the human immune system will respond in the same manner, but this is not to say that this would be sufficient to provide complete protection."

To increase the potency of the vaccine, these scientists are therefore going to add more HIV proteins together with other compounds that reinforce the body's reaction to HIV-specific proteins. In parallel with this, they will work to select a suitable vegetable that is easy to cultivate in different climates and is readily accepted in different cultures. Thus far, thale cress (Arabidopsis thaliana) has been used as an experimental plant, a common wild plant that is related to mustard and cabbage and has the great advantage of being well mapped genetically.

"The carrot is a good candidate for producing an edible vaccine, not least because it can be eaten raw, which reduces the risk of the proteins being destroyed by heating. What's more, it's a biennial, which means that it doesn't go to seed the first year, making it easier to ensure that it doesn't spread its genes to other plants close by," explains Ingrid Lindh.

Understanding Network Security Principles

2009-05-13T18:28:00.000-07:00

As networks grow and interconnect with other networks, including the Internet, those
networks are exposed to a greater number of security risks. Not only does the number of
potential attackers grow along with the size of the network, but the tools available to those
potential attackers are always increasing in terms of sophistication.

Where do most attacks on an organization’s computer resources originate?

From the Internet

From the inside network

From universities

From intruders who gain physical access to the computer resources

What are the three primary goals of network security? (Choose three.)

Confidentiality

Redundancy

Integrity

Availability

The U.S. government places classified data into which classes? (Choose three.)

SBU

Confidential

Secret

Top-secret

Cisco defines three categories of security controls: administrative, physical, and

technical. Individual controls within these categories can be further classified as what

three specific types of controls? (Choose three.)

Preventive

Deterrent

Detective

Reactive

Litigators typically require which three of the following elements to present an

effective argument when prosecuting information security violations? (Choose three.)

Audit trail

Motive

Means

Opportunity

Which type of law typically involves the enforcement of regulations by government

agencies?

Criminal law

Tort law

Administrative law

Civil law

Parts of Obama's Green Energy Plan Fuel Discontent Among Environmentalists

2009-05-05T17:59:00.000-07:00

Many local activists say the rush to renewables, backed by Obama, risks trading one power problem for another

By Dan Springer

FOXNews.com

A key part of President Obama's energy plan -- replacing fossil fuels with green alternatives -- is facing increasing opposition from an unlikely source: environmentalists.

Some environmentalists, who have successfully fought a wind farm on the border of Oregon and Washington, are trying to block a massive solar plant in the Mojave desert. And now an Oregon county is considering a ban on wind power in the foothills of the blue mountains.

"We all want to be as green as we can be. But at what cost?" Richard Jolly of the Blue Mountain Alliance. "To take everything from us? This valley could be surrounded by them."

Jolly says 400-foot wind turbines are a bird-killing eyesore. The developer argues the danger to birds is exaggerated but admits every big energy project has its downside.

"If we hold out for the perfect environmental silver bullet, if you will, it will always be 15 years down the road," he said. "We have to make incremental progress."

For decades, environmental groups have talked about "big oil," painting the petroleum industry as greedy and destructive. Now similar language is being applied to renewables. Instead of eco-friendly green power, increasingly it's "big wind" and "big solar."

Large environmental groups, such as the Natural Resources Defense Council, bristle at the idea of dissension in the ranks.

"We are working very aggressively to make a planning process happen with utilities, with industry, with local groups all at the table," said Rick Duke, director of the Natural Resources Defense Council's Center for Market Innovation.

Obama has set a goal of getting 25 percent of the nation's power from renewable sources by 2025. The White House contends that will create millions of jobs and has the support of business and environmental leaders.

But many local activists say we need to slow this rush to renewables or risk trading one power problem for anothe

CT scan reveals hidden face under Nefertiti bust

2009-03-31T18:43:00.000-07:00

BERLIN – Researchers in Germany have used a modern medical procedure to uncover a secret within one of ancient Egypt's most treasured artworks — the bust of Nefertiti has two faces. A team led by Dr. Alexander Huppertz, director of the Imaging Science Institute at Berlin's Charite hospital and medical school, discovered a detailed stone carving that differs from the external stucco face when they performed a computed tomography, or CT, scan on the bust.

The findings, published Tuesday in the monthly journal Radiology, are the first to show that the stone core of the statue is a highly detailed sculpture of the queen, Huppertz said.

"Until we did this scan, how deep the stucco was and whether a second face was underneath it was unknown," he said. "The hypothesis was that the stone underneath was just a support."

The differences between the faces, though slight — creases at the corners of the mouth, a bump on the nose of the stone version — suggest to Huppertz that someone expressly ordered the adjustments between stone and stucco when royal sculptors immortalized the wife of Pharaoh Akhenaten 3,300 years ago.

"Changes were made, but some of them are positive, others are negative," Huppertz said.

John H. Taylor, a curator for Ancient Egypt and Sudan at the British Museum in London, said the scan raises interesting questions about why the features were adjusted — but that answers will probably remain elusive.

"One could deduce that the final version was considered in some way more acceptable than the 'hidden' one, though caution is needed in attempting to explain the significance of these changes," Taylor wrote in an e-mail.

The bust underwent a similar CT scan in 1992. But the more primitive scanner used then only generated cross sections of the statue every 5 millimeters — not enough detail, Huppertz said, to reveal the subtlety of the carving hidden just 1-2 millimeters under the stucco.

Egyptologist Ludwig Borchardt discovered the bust in 1912 and added it to Berlin's Egyptian collection on Museum Island, a cluster of five neoclassical art halls that make up one of the city's most familiar landmarks.

Currently on display at the Altes Museum, the bust will move next door when the Neues Museum reopens in October after a lengthy restoration by British architect David Chipperfield.

In 2007, Wildung denied a request from Egypt's antiquities chief to borrow the bust for an exhibition, saying it was too fragile to transport. Huppertz said the results of his scan added credence to that claim.

Taylor, the British Museum curator, said the better understanding of the bust's structure will also help preserve it.

"The findings are particularly significant for the information they shed on the constructional process and the subsurface condition of the bust, which will be of value in ensuring its long-term survival in good condition" Taylor said.

source : yahoo.com

“JEMPENG” (SARINGAN BATU CADAS) DI BALI

2009-02-27T21:44:00.000-08:00

PENDAHULUAN
Kebutuhan akan air bersih di daerah pedesaan dan pinggiran kota untuk air minum, memasak , mencuci dan sebagiannya harus diperhatikan. Cara penjernihan air perlu diketahui karena semakin banyak sumber air yang tercemar limbah rumah tangga maupun limbah industri.
Cara penjernihan air baik secara alami maupun kimiawi akan diuraikan dalam bab ini. Cara-cara yang disajikan dapat digunakan di desa karena bahan dan alatnya mudah didapat. Bahan-bahannya anatara lain batu, pasir, kerikil, arang tempurung kelapa, arang sekam padi, tanah liat, ijuk, kaporit, kapur, tawas, biji kelor dan lain-lain.
URAIAN SINGKAT
Sumber air minum yang umum digunakan oleh masyarakat desa Kerobokan, Bali berasal dari sumur gali, dan dari saluran irigasi sawah yang disaring dengan Jempeng yaitu saringan air yang terbuat dari batu cadas. Alat penyaring air minum ini merupakan teknologi yang telah membudaya di masyarkata di desa tersebut. Cara ini dapat digunakan di daerah yang banyak terdapat batu cadas.
BAHAN
1. Batu cadas, tergolong ke dalam jenis tanah keras/padat seperti : batu gunung.
2. Beton (koral, pasir dan semen)
3. Kolam
PERALATAN
1. Alat penyaring air minum “Jempeng” untuk menyaring air kolam yang berasal dari saluran irigasi sawah.
2. Jempeng bentuk U atau jempeng bentuk W atau jempeng setengah sgi enam.
PEMBUATAN
Jempeng yang umum dipakai oleh penduduk rata-rata ketebalan dindingnya berkisar 7 sampai 12 cm, tinggi 60 cm dan diameternya 40 cm diukur dari luar.

Gambar 1. Bentuk dan ukuran jempeng
Macam/jenis jempeng Bali :
1. Jempeng bentuk U, jempeng ini keseluruhannya terbuat dari batu cadas. Bagian bawahnya berbentuk penyungkup setengah bola, badan saringan berbentuk silinder, sedang bagian atasnya terbuka, sehingga penampang vertikalnya berbentuk huruf U.
2. Jempeng berbentuk huruf W, tidak seluruhnya terbuat dari batu cadas. Sisi bawah dan ketiga sisi samping, terbuat dari beton kedap air. Hanya satu buah sisinya yaitu sisi tengah terbuat dari lempengan batu cadas, seang bagian atasnya terbuka.
3. Jempeng yang bagian bawahnya berbentuk setengah segi enam, seperti
  Gambar 1, keseluruhanya terbuat dari batu cadas.
  Badan jempengan berbentuk silinder dan bagian atasnya juga terbuka.
  ( 1 )
  ( 2 )
  ( 3 )
  Gambar 2. Model-model jempeng
PENGGUNAAN
Jempeng digunakan dengan cara diletakkan dalam aliran air supaya air meresap. Daya kerja saringan jempeng dalam penggunaannya untuk menyaring air minum dipengaruhi oleh beberapa faktor :
1. Besar kecilnya diameter pori bahan saringan
2. Derajat kekeruhan air
3. Suhu air
4. Derajat keasaman (ph) air
5. Tekanan air pada dinding saringan, dan
6. Tebal tipisnya dinding saringan
  Air yang dihasilkan untuk jempeng dengan ketebalan 13 cm adalah 3,8 1/jam
KEUNTUNGAN
1. Daya saring jempeng tidak berpengaruh terhadap kesadahan air kolam stelah disaring. Bahan baku jempeng (batu cadas) tidak mengandung unsur-unsur kimia yang dpaat mempengaruhi kesadahan air kolam sebelum dan sesudah disaring.
2. Saringan tersebut telah lama digunakan oleh masyarakat desa Kerobokan, sehingga boleh dikatakan pemakaiannya telah membudidaya di kalangan
  masyarakat desa tersebut.
3. Semakin tebal dinding jempeng, semakin kecil bakteri golongan coli setelah penyaringan.
KERUGIAN
1. Rata-rata debit air minum yang dihasilkan oleh jempeng dengan ketebalan dinding 13 cm, belum cukup untuk memenuhi kebutuhan air minum suatu keluarga yang beranggotakan 5 orang lebih.
2. Belum dapat diketahui setelah berapa lama jempeng tersebut perlu dibersihkan dari lumut, ganggang/algae yang tumbuh pada permukaan jempeng.
DAFTAR PUSTAKA
Kusnoputranto, Haryoto et al. Daya kerja “Jempeng” sebagai saringan sederhana untuk me-nyaring air minum di desa Kerobokan, Kecamatan Kuta, Kab. Badung, Bali. Dalam Lokakarya Penelitian dan Pengembangan Teknologi Tepat Guna Penyediaan Air Minum dan Pembuangan/Pengolahan Kotoran di
pedesaan. Cimacan, 2-4 Februari 1981. Jakarta : Badan Penelitian dan Pengembangan Kesehatan, Departemen Kesehatan R.I., Jl. Percetakan negara
I, Telp. 414-226, Jakarta.
INFORMASI LEBIH LANJUT
1. Pusat Penelitian dan Pengembangan Fisika Terapan – LIPI; Jl. Cisitu Sangkuriang No. 1 – Bandung 40134 - INDONESIA; Tel.+62 22 250 3052, 250 4826, 250 4832, 250 4833; Fax. +62 22 250 3050
2. Pusat Informasi Wanita dalam Pembangunan PDII-LIPI; Sasana Widya Sarwono, Jl. Jend. Gatot Subroto 10 Jakarta 12710, INDONESIA.

Sumber : Buku Panduan Air dan Sanitasi, Pusat Informasi Wanita dalam Pembangunan PDII-LIPI bekerjasama dengan Swiss Development Cooperation, Jakarta, 1991.

source : iptek.net.id

Cardiac CT for Calcium Scoring

2009-02-27T19:43:00.001-08:00

What is Cardiac CT for Calcium Scoring?

CT scanning—sometimes called CAT scanning—is a noninvasive medical test that helps physicians diagnose and treat medical conditions.

CT imaging combines special x-ray equipment with sophisticated computers to produce multiple images or pictures of the inside of the body. These cross-sectional images of the area being studied can then be examined on a computer monitor or printed.

CT scans of internal organs, bone, soft tissue and blood vessels provide greater clarity and reveal more details than regular x-ray exams.

A cardiac CT scan for coronary calcium is a non-invasive way of obtaining information about the presence, location and extent of calcified plaque in the coronary arteries—the vessels that supply oxygen-containing blood to the heart wall. Calcified plaque is a build-up of fat and other substances, including calcium, and is a sign of atherosclerosis a disease of the vessel wall, which is called coronary artery disease (CAD). People with this disease have an increased risk for heart attacks. In addition, over time, progression of plaque build up (CAD) can narrow the arteries or even close off blood flow to the heart. The result may be painful angina in the chest or a heart attack.

Because calcium is a marker of CAD, the amount of calcium detected on a cardiac CT scan is a helpful prognostic tool. The findings on cardiac CT are expressed as a calcium score. Another name for this test is coronary artery calcium scoring.

What are some common uses of the procedure?

The goal of cardiac CT for calcium scoring is to determine if CAD is present and to what extent, even if there are no symptoms. It is a screening study that may be recommended by a physician for patients with risk factors for CAD but no clinical symptoms.

The major risk factors for CAD are:

abnormally high blood cholesterol levels
a family history of heart disease
diabetes
high blood pressure
cigarette smoking
being overweight or obese
being physically inactive

How should I prepare?

No special preparation is necessary in advance of a cardiac CT examination. You may continue to take your usual medications, but should avoid caffeine and smoking for four hours before the exam.

You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure.

Metal objects including jewelry, eyeglasses, dentures and hairpins may affect the CT images and should be left at home or removed prior to your exam. You may also be asked to remove hearing aids and removable dental work.

Women should always inform their physician and the CT technologist if there is any possibility that they are pregnant. See the Safety page for more information about pregnancy and x-rays.

What does the equipment look like?

The CT scanner is typically a large, box like machine with a hole, or short tunnel, in the center. You will lie on a narrow examination table that slides into and out of this tunnel. Rotating around you, the x-ray tube and electronic x-ray detectors are located opposite each other in a ring, called a gantry. The computer workstation that processes the imaging information is located in a separate room, where the technologist operates the scanner and monitors your examination.

How does the procedure work?

In many ways CT scanning works very much like other x-ray examinations. X-rays are a form of radiation—like light or radio waves—that can be directed at the body. Different body parts absorb the x-rays in varying degrees.

In a conventional x-ray exam, a small burst of radiation is aimed at and passes through the body, recording an image on photographic film or a special image recording plate. Bones appear white on the x-ray; soft tissue shows up in shades of gray and air appears black.

With CT scanning, numerous x-ray beams and a set of electronic x-ray detectors rotate around you, measuring the amount of radiation being absorbed throughout your body. At the same time, the examination table is moving through the scanner, so that the x-ray beam follows a spiral path. A special computer program processes this large volume of data to create two-dimensional cross-sectional images of your body, which are then displayed on a monitor. This technique is called helical or spiral CT.

CT imaging is sometimes compared to looking into a loaf of bread by cutting the loaf into thin slices. When the image slices are reassembled by computer software, the result is a very detailed multidimensional view of the body's interior.

Refinements in detector technology allow new CT scanners to obtain multiple slices in a single rotation. These scanners, called "multislice CT" or "multidetector CT," allow thinner slices to be obtained in a shorter period of time, resulting in more detail and additional view capabilities.

Modern CT scanners are so fast that they can scan through large sections of the body in just a few seconds. Such speed is beneficial for all patients but especially children, the elderly and critically ill.

How is the procedure performed?

The technologist begins by positioning you on the CT examination table, usually lying flat on your back or possibly on your side or on your stomach. Straps and pillows may be used to help you maintain the correct position and to hold still during the exam.

Electrodes (small metal discs) will be attached to your chest and to an electrocardiograph (ECG) machine that records the electrical activity of the heart. This makes it possible to record CT scans when the heart is not actively contracting.

Next, the table will move quickly through the scanner to determine the correct starting position for the scans. Then, the table will move slowly through the machine as the actual CT scanning is performed.

Patients are asked to hold their breath for a period of 20 to 30 seconds while images are recorded.

When the examination is completed, you will be asked to wait until the technologist verifies that the images are of high enough quality for accurate interpretation.

The entire procedure including the actual CT scanning is usually completed within 10 minutes.

What will I experience during and after the procedure?

Most CT exams are painless, fast and easy. With helical CT, the amount of time that the patient needs to lie still is reduced.

Though the scanning itself causes no pain, there may be some discomfort from having to remain still for several minutes. If you have a hard time staying still, are claustrophobic or have chronic pain, you may find a CT exam to be stressful. The technologist or nurse, under the direction of a physician, may offer you a mild sedative to help you tolerate the CT scanning procedure.

When you enter the CT scanner, special lights may be used to ensure that you are properly positioned. With modern CT scanners, you will hear only slight buzzing, clicking and whirring sounds as the CT scanner revolves around you during the imaging process.

You will be alone in the exam room during the CT scan, however, the technologist will be able to see, hear and speak with you at all times.

After a CT exam, you can return to your normal activities.

Who interprets the results and how do I get them?

A physician, usually a radiologist with expertise in supervising and interpreting radiology examinations, will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you.

A negative cardiac CT scan shows no calcification within the coronary arteries. This suggests that CAD is minimal and that the chance of having a heart attack over the next two to five years is very low.

A positive test means that CAD is present, regardless of whether or not the patient is experiencing any symptoms. The amount of calcification—expressed as the calcium score—may help to predict the likelihood of a myocardial infarction (heart attack) in the coming years.

The extent of CAD is graded according to your calcium score:

Calcium Score	Presence of CAD
0	No evidence of CAD
1-10	Minimal evidence of CAD
11-100	Mild evidence of CAD
101-400	Moderate evidence of CAD
Over 400	Extensive evidence of CAD

What are the benefits vs. risks?

Benefits

Cardiac CT for calcium scoring is a convenient and noninvasive way of evaluating whether you may be at increased risk for a heart attack.
The exam takes little time, causes no pain, and does not require injection of contrast material.
No radiation remains in a patient's body after a CT examination.
X-rays used in CT scans usually have no side effects.

Risks

There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk.
The effective radiation dose from this procedure is about 2 mSv, which is about the same as the average person receives from background radiation in eight months. See the Safety page for more information about radiation dose.
Women should always inform their physician and x-ray or CT technologist if there is any possibility that they are pregnant. See the Safety page for more information about pregnancy and x-rays.
CT scanning is, in general, not recommended for pregnant women unless medically necessary because of potential risk to the baby.
A high calcium score may sometimes be followed by other diagnostic tests for heart disease, which may not be necessary and might cause side effects.

What are the limitations of Cardiac CT for Calcium Scoring?

A person who is very large may not fit into the opening of a conventional CT scanner or may be over the weight limit for the moving table.

CAD, especially in people below 50 years of age can be present without calcium and may not be detected by this exam.

Not all health insurance plans cover cardiac CT for calcium scoring.

A high heart rate may interfere with the test. If a patient's heart rate is 90 or more beats per minute, the exam may need to be rescheduled.

Exactly how your treatment or prevention for heart attacks should be modified according to your calcium score remains uncertain.

source : radiologyinfo.org

CT - Body

2009-02-27T19:34:00.001-08:00

What is CT Scanning of the Body?

CT scanning—sometimes called CAT scanning—is a noninvasive medical test that helps physicians diagnose and treat medical conditions.

CT scans of internal organs, bone, soft tissue and blood vessels provide greater clarity and reveal more details than regular x-ray exams.

Using specialized equipment and expertise to create and interpret CT scans of the body, radiologists can more easily diagnose problems such as cancers, cardiovascular disease, infectious disease, trauma and musculoskeletal disorders.

What are some common uses of the procedure?

CT imaging is:

one of the best and fastest tools for studying the chest, abdomen and pelvis because it provides detailed, cross-sectional views of all types of tissue.
often the preferred method for diagnosing many different cancers, including lung, liver and pancreatic cancer, since the image allows a physician to confirm the presence of a tumor and measure its size, precise location and the extent of the tumor's involvement with other nearby tissue.
an examination that plays a significant role in the detection, diagnosis and treatment of vascular diseases that can lead to stroke, kidney failure or even death. CT is commonly used to assess for pulmonary embolism (a blood clot in the lung vessels) as well as for abdominal aortic aneurysms (AAA).
invaluable in diagnosing and treating spinal problems and injuries to the hands, feet and other skeletal structures because it can clearly show even very small bones as well as surrounding tissues such as muscle and blood vessels.

Physicians often use the CT examination to:

quickly identify injuries to the lungs, heart and vessels, liver, spleen, kidneys or other internal organs in cases of trauma
guide biopsies and other procedures such as abscess drainages and minimally invasive tumor treatments
plan for and assess the results of surgery
plan and properly administer radiation treatments for tumors
measure bone mineral density for the detection of osteoporosis

How should I prepare?

You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure.

You may be asked not to eat or drink anything for several hours beforehand, especially if a contrast material will be used in your exam. You should inform your physician of any medications you are taking and if you have any allergies. If you have a known allergy to contrast material, or "dye," your doctor may prescribe medications to reduce the risk of an allergic reaction.

Also inform your doctor of any recent illnesses or other medical conditions, and if you have a history of heart disease, asthma, diabetes, kidney disease or thyroid problems. Any of these conditions may increase the risk of an unusual adverse effect.

Women should always inform their physician and the CT technologist if there is any possibility that they are pregnant. See the Safety page for more information about pregnancy and x-rays.

What does the equipment look like?

How does the procedure work?

CAT scan: liver

CAT scan: abdominal

CAT scan: appendix

For some CT exams, a contrast material is used to enhance visibility in the area of the body being studied.

How is the CAT scan performed?

If contrast material is used, it will be swallowed, injected through an intravenous line (IV) or administered by enema, depending on the type of examination.

You may be asked to hold your breath during the scanning.

When the examination is completed, you will be asked to wait until the technologist verifies that the images are of high enough quality for accurate interpretation.

CT scanning of the body usually lasts between five and 30 minutes.

What will I experience during and after the procedure?

Most CT exams are painless, fast and easy. With helical CT, the amount of time that the patient needs to lie still is reduced.

If an intravenous contrast material is used, you will feel a slight pin prick when the needle is inserted into your vein. You may have a warm, flushed sensation during the injection of the contrast materials and a metallic taste in your mouth that lasts for a few minutes. Occasionally, a patient will develop itching and hives, which can be relieved with medication. If you become light-headed or experience difficulty breathing, you should notify the technologist or nurse, as it may indicate a more severe allergic reaction. A radiologist or other physician will be available for immediate assistance.

If the contrast material is swallowed, you may find the taste mildly unpleasant; however, most patients can easily tolerate it. You can expect to experience a sense of abdominal fullness and an increasing need to expel the liquid if your contrast material is given by enema. In this case, be patient, as the mild discomfort will not last long.

You will be alone in the exam room during the CT scan, however, the technologist will be able to see, hear and speak with you at all times.

With pediatric patients, a parent may be allowed in the room but will be required to wear a lead apron to prevent radiation exposure.

After a CT exam, you can return to your normal activities. If you received contrast material, you may be given special instructions.

Who interprets the results and how do I get them?

What are the benefits vs. risks?

Benefits

CT scanning is painless, noninvasive and accurate.
A major advantage of CT is that it is able to image bone, soft tissue and blood vessels all at the same time.
Unlike conventional x-rays, CT scanning provides very detailed images of many types of tissue as well as the lungs, bones, and blood vessels.
CT examinations are fast and simple; in emergency cases, they can reveal internal injuries and bleeding quickly enough to help save lives.
CT has been shown to be a cost-effective imaging tool for a wide range of clinical problems.
CT is less sensitive to patient movement than MRI.
CT can be performed if you have an implanted medical device of any kind, unlike MRI.
CT imaging provides real-time imaging, making it a good tool for guiding minimally invasive procedures such as needle biopsies and needle aspirations of many areas of the body, particularly the lungs, abdomen, pelvis and bones.
A diagnosis determined by CT scanning may eliminate the need for exploratory surgery and surgical biopsy.
No radiation remains in a patient's body after a CT examination.
X-rays used in CT scans usually have no side effects.

Risks

There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk.
The effective radiation dose from this procedure ranges from approximately two to 10 mSv, which is about the same as the average person receives from background radiation in three to five years. See the Safety page for more information about radiation dose.
Women should always inform their physician and x-ray or CT technologist if there is any possibility that they are pregnant. See the Safety page for more information about pregnancy and x-rays.
CT scanning is, in general, not recommended for pregnant women unless medically necessary because of potential risk to the baby.
Nursing mothers should wait for 24 hours after contrast material injection before resuming breast-feeding.
The risk of serious allergic reaction to contrast materials that contain iodine is extremely rare, and radiology departments are well-equipped to deal with them.
Children should have a CT study only if it is essential for making a diagnosis and should not have repeated CT studies unless absolutely necessary.

What are the limitations of CT Scanning of the Body?

Soft-tissue details in areas such as the brain, internal pelvic organs, knee or shoulder can be more readily and clearly seen with magnetic resonance imaging (MRI). The exam is not generally indicated for pregnant women.

A person who is very large may not fit into the opening of a conventional CT scanner or may be over the weight limit for the moving table.

Additional Information and Resources:

RTAnswers.org:

Radiation Therapy for Lymphoma

Electronic Health Record & Electronic Medical Record

2008-11-12T21:34:00.000-08:00

Electronic Medical Record system allows healthcare providers to save time and money, enabling them to better care for their patients. EMR patient tracking software centralizes patient medical records and streamlines the diagnosis and treatment processes. It allows physicians to efficiently and cost-effectively manage their patients’ full clinical experience, including appointment scheduling, office visits, labs, health maintenance, referrals, authorization and medications.

Electronic Medical Record Software System

EMR system is one of the most complete, efficient and affordable electronic medical record software. MedicWare EMR is medical office software that increases profitability of your practice, improves efficiency of your staff, and enhances your patient care. EMR software allows providers to efficiently and cost-effectively manage their patient's complete clinical experience including appointment scheduling, office visits, medical histories, examinations, electronic prescribing, plans, charge capture, labs, health maintenance, referrals, authorizations, medications and prescribing software. EMR electronic health record software is not only patient medical record software, but also is also an important part of your medical office management software.

Electronic Medical Record Subscription

This is your answer if you want the power of EMR software, our patient medical record software, without the burden of purchasing and maintaining a computer server. Get all the benefits of our powerful electronic health record system without the day-to-day responsibility of maintaining a server and keeping your patient medical record safe and secure.

Charge Capture and Electronic Prescribing Software

PDA medical software designed to keep track of your appointments, billing charges and electronically prescribe medication anytime, anywhere. It fits into the palm of your hand: Patient Tracking Charge Capture and Electronic Prescribing software. All you need is a Pocket PC PDA. No need to change your office workflow. No need for continuous wireless or wired connection. It even sends the billing charges to your medical office management software and the prescription to the pharmacy. You can get all of these benefits for the cost of a cup of coffee a day.
from : medicware.com

IT-Green™ : Computer Recycling services

2008-10-15T20:30:00.000-07:00

IT-Green™ offers leading Computer Recycling services for Corporate, Educational and Government bodies throughout the United Kingdom. A policy of zero landfill coupled with relevant licenses and a professional service means that IT-Green guarantees:

The removal of all corporate identification.

Compliance with stringent environmental legislation.

Work carried out with minimal disruption to your business.

Trained, uniformed personnel.

A cost effective solution.

Tracking your redundant assets, removing valuable data and outsourcing an ethical recycling route can be time consuming and costly. We offer an end to end service, reducing your overheads and the burden placed upon your I.T staff.

The recycling service offered by IT-Green™ for redundant Computer Baseunits ensures:

Resource extraction from obsolete or faulty Computers.
Re-use of Components deemed to have residual life.
Bespoke data wiping* solutions to meet the most stringent requirements.
Tracking of redundant computers throughout the recycling process.
Certification* where requested as part of a contract.
Non export of your discarded hardware.

As part of our service, we are legally obliged to produce a transfer notice, documenting the quantities of Computer waste transferred into our posession. Our collection staff will issue you with a copy of this notice, along with a EWC (European Waste Catalogue) coding note at the time of collection.

We re-process all obsolete Computer hardware in-house and baseunits are stripped to their constituent components before being passed onto vetted processing plants for base materials extraction inside the UK, thus ensuring no resources are wasted.

Our collection staff will be happy to advise you with regard to discharging your legal obligations when a collection is carried out. For more information, or to request a quotation, please contact us using the number shown at the top of this page.

Integration of modeling and simulation into hospital-based decision support systems guiding pediatric pharmacotherapy

2008-09-28T20:22:00.000-07:00

Jeffrey S Barrett¹ , John T Mondick¹ , Mahesh Narayan¹ , Kalpana Vijayakumar² and Sundararajan Vijayakumar²

¹Department of Pediatrics, Division of Clinical Pharmacology and Therapeutics, The Children's Hospital of Philadelphia, USA

²INTEK Partners, Inc., 676 Route 202-206 North, Bridgewater, NJ 08807, USA

Background

Decision analysis in hospital-based settings is becoming more common place. The application of modeling and simulation approaches has likewise become more prevalent in order to support decision analytics. With respect to clinical decision making at the level of the patient, modeling and simulation approaches have been used to study and forecast treatment options, examine and rate caregiver performance and assign resources (staffing, beds, patient throughput). There us a great need to facilitate pharmacotherapeutic decision making in pediatrics given the often limited data available to guide dosing and manage patient response. We have employed nonlinear mixed effect models and Bayesian forecasting algorithms coupled with data summary and visualization tools to create drug-specific decision support systems that utilize individualized patient data from our electronic medical records systems.

Decision making in a hospital environment occurs at multiple levels of the organization and in a variety of departmental settings. Likewise, numerous stakeholders including hospital administration, staffing planners, facilities management, pharmacy administration, caregivers and physicians as well as healthcare providers are reliant on decision support systems (DSS) to facilitate decision making in their specific areas. Ultimately, the outcome, at least in theory, should be better decisions yielding more efficient provision of services and optimal (most appropriate and cost-effective) patient care. Informing today's decision makers is a cadre of tools and decision analytics. Historically, hospital environments have not been the hallmark of innovation in decision analytics and the discrepancy between the hospital environment and other industries has received a great deal of attention recently. In late 2005, the National Academies of Engineering and Institute of Medicine issued a joint report that cited the urgency and importance of bringing contemporary System Engineering techniques to healthcare. Annual gross waste of a staggering 30–40% of every dollar spent in healthcare and continued medical errors that cause nearly 100,000 patient deaths and serious injuries yearly were only two of the more serious problems covered in the report [1,2]. This situation is changing in a dramatic manner as information technology, engineering, clinical and informatics scientists collaborate on analytic approaches that address decision requirements of the current inpatient environment.

The backbone of many decision support systems typically consist of transactional and/or relational databases and models which describe, predict and/or simulate response to varied inputs. Table 1 illustrates the diversity in modeling and simulation application in the hospital setting [3-21]. The examples are representative as this is certainly not an exhaustive account. Along with the varied applications are diverse physical and stochastic models and analytics. The choice of approach is dependent upon the objectives of the application of course but there exists a great deal of overlap between modeling approaches and procedures yielding the possibility of multiple solutions to decision making questions. Our purpose is not to review such approaches (although such a review is needed) but rather to focus on the use of nonlinear mixed effect modeling to guide decisions regarding the use and management of drugs to treat patients – pharmacotherapy.

Table 1. Diversity in modeling and simulation applications in the hospital setting

Pharmacotherapy is generally concerned with the safe and effective management of drug administration. It implies an understanding of drug pharmacokinetics (PK) and pharmacodynamics (PD) so that individual dosing guidance, when necessary, can be provided to optimize patient response within their individual therapeutic window. Pediatric pharmacotherapy can be challenging due to developmental changes that may alter drug kinetics, pathophysiologic differences that may alter pharmacodynamics, disease etiologies that may be different from adults, and other factors that may result in great variation in safety and efficacy outcomes. The situation becomes more convoluted when one considers children and the paucity of well-controlled pediatric clinical trials. This situation, despite the efforts of the Food and Drug Administration and the US Congress, is not likely to improve substantially due to the economic reality of the pediatric market.

Population pharmacokinetics is an approach to explain sources of variation in various pharmacokinetic processes across individual patient populations [22,23]. The nature of the sources of variation varies with drug and the underlying pharmacokinetic (structural) model can be simple or complex. Variation is also relevant to the population being studied and pediatrics represents a particularly dynamic setting given the many developmental changes which occur as children develop [24]. Nonlinear mixed effects models involve both fixed effects and random effects. Model building for nonlinear mixed effects is the process of determining the characteristics of both the fixed and the random effects in order to produce a predictive, generalizable and parsimonious model. Procedures based on information criterion statistics for comparing different structures of the random effects component are generally suitable to achieve a model which is both adequate to explain the sample data and, upon validation against an external data set, generalizable to the broader population (see Figure 1). Historically, therapeutic drug monitoring (TDM) has been used to monitor/guide pharmacotherapy particularly for agents with a narrow therapeutic index. Often, the monitored drug levels are judged against historical "norms" and not necessarily viewed in the context of specific factors which may suggest a different scale by which they should be judged. Also, time dependencies are seldom considered in these static devices. A model-based approach on the contrary has the ability to both account for demonstrated relevant patient factors (covariate model) and/or group (disease status) factors. While some attempts have been made to interface TDM data to therapeutic drug models, these have been developed for standalone applications and not with the physician caregiver in mind [25,26].

Figure 1. Typical progression of pharmacometric model development commonly used to support pharmacotherapeutic decision support systems.

We have begun to interface our electronic medical record system with decision support analytics (drug dashboards) that summarize individual patient records and assemble the most relevant clinical data associated with drug therapy. Data visualization tools summarize patient profiles of lab values, vital signs, and associated biomarkers into tables and plots based on user-defined requirements. More importantly, this data populates models that predict future events as drug therapy continues. A prototype methotrexate dashboard is demonstrated. A population-based pharmacokinetic model (nonlinear mixed effect model) is used to simulate individual patient MTX drug concentrations based on that patient's current dosing regimen and compares expected exposures with nomograms that predict toxicity. The compilation of additional dashboards is planned for the construction of a larger pediatric knowledgebase (PKB) currently under construction. Our objective is to define the general approach of pharmacostatistical model building while demonstrating how such models can be interfaced to electronic medical record data front-ended by a web-based decision support system.

Methods

Population Pharmacokinetics

Population pharmacokinetics is the study of the sources and correlates of variability in drug concentrations among individuals who represent the target patient population receiving clinically relevant doses of a drug of interest. The goal of population pharmacokinetic analysis to identify pathophysiologic factors that cause changes in the dose-concentration relationship and the extent of these changes so that, if such changes are associated with clinically significant shifts in the therapeutic index, dosage can be appropriately modified. Population pharmacokinetic models adhere into a hierarchical structure. At the initial stage, the relationship between concentration and time (pharmacokinetics) is modeled for an individual patient. At the second stage, pharmacokinetic parameters that define each of the individual patients' drug concentration profiles are assigned some distributional form, after accounting for relevant covariate information. A primary aim of a population analysis is to determine covariates that are important predictors of pharmacokinetic parameters. A Bayesian model then requires a third stage in which prior distributions are specified for the parameters defining the second-stage distributional form and the intra-individual variance parameters. Such a Bayesian model defines and estimates the variability that is observed both in individual concentrations and between different individuals' pharmacokinetic parameters. This model framework makes it is possible to determine appropriate patient-specific dosage regimens that ensure the attainment of desirable drug concentrations.

The estimation method most commonly used in population pharmacokinetics and nonlinear mixed effect modeling in general is based on a maximum likelihood approach. Maximum Likelihood (ML) is an alternative to the least squares objective function; it seeks to maximize the likelihood or log-likelihood function (or to minimize the negative log-likelihood function). In general terms, the likelihood function is defined as:

The probability (now called L, the likelihood) is predicted in the sample data, given the respective regression model. Provided that all observations are independent of each other, this likelihood is the geometric sum (Π, across i = 1 to n cases) of probabilities for each individual observation (i) to occur, given the respective model and parameters (θ's) for the x values. As it is customary to express this function as a natural logarithm, the geometric sum becomes a regular arithmetic sum (Σ, across i = 1 to n cases). The larger the likelihood of the model, the larger is the probability of the dependent variable values to occur in the sample and the better is the fit of the model to the data. If all assumptions for standard multiple regression are met, then the standard least squares estimation method will yield results identical to the maximum likelihood method. If the assumption of equal error variances across the range of the x variable(s) is violated, then the weighted least squares method will yield maximum likelihood estimates.

The typical structural model is chosen from one of several compartmental models which incorporate the route of administration as a fixed input into the model with certain assumptions (i.e., linear or zero order input). Compartmental models are, for the most part, empirical even though they may incorporate some mechanistic assumptions so they appear more realistic. Numerically, they are generally easier to handle as opposed to mechanistic models. Complex mechanistic and/or highly parameterized structural models can be accommodated as well of course. The prediction engine discussed herein is not limited by the nature of the model definition.

The framework for the mixed effect modeling approach to population pharmacokinetic analysis can be defined as follows: for i = 1, ... n individuals in a population of interest, let x_ij, j = 1, ... n_jrepresent the design points on which the y_ijresponses are observed. In the pharmacokinetic (PK) setting, x_ijare typically the sampling time points and y_ijare the observed concentrations in the biologic matrix of interest (usually plasma or blood). Hence, the PK response can be described by

y_ij= f(θ_i, x_ij) + ε_ij

where the function f denotes the structural model; θ_iis the p × 1 parameter vector for the i^thindividual and ε_ijare the independently and identically distributed (i.i.d.) error terms assumed to be normal random variables with a zero mean and a variance (σ_e²) which may depend on the mean concentration. The ε_ij's account for the intraindividual variability and may incorporate model misspecification or other unresolved (or incorrect) error partitioning. In most population pharmacokinetic software the structural model is chosen from a library of compartmental models, expressed as a closed form system of equations or defined via differential equations. The probability density function which accounts for the within-individual variability only as

p(y_ij| θ_i, x_ij)

The intra-individual variation about the ith individual is defined when the distribution ε_iof is specified. The second stage model defines the between-individual variability in the parameters as follows

θ_i= θ + η_i

where θ is the mean parameter vector for the population and η_iare the individual deviations assumed to be i.i.d. and normal with zero mean vector and covariance matrix Ω. The expression of θ_ishown (additive) is one of numerous ways that individual θ's can be defined. In addition, the population θ can be expressed as a function of covariates (β_i). The covariate matrix Ω captures both the variance and covariance among the η's. The density of the second stage model can then be defined as

p(θ_i| θ, Ω, β_i)

where β_irepresents the individual patient covariate data (i.e., age, sex, race, etc.). The third stage of the mixed effect model approach would represent a Bayesian representation in which the model would contain the prior distributions of the population parameters as mentioned previously.

Prediction Models for Toxicity and Adverse Events

PK/PD models can be developed to explore the relationship between drug exposure and observed toxicity as well. Endpoints can be expressed as a dichotomous categorical variable representing the occurrence of an adverse effect (AE, e.g., nausea, vomiting) or drug reaction (1 = yes, 0 = no). The population PD data are viewed as a probabilistic outcome and analyzed using a logistic regression model [27]. The probability of an event for individual i at sampling time j is given by p_ij. The ratio of the probability of that event occurring vs. the probability that it does not occur is given by the Odds Ratio; the log of the Odds Ratio is known as the logit function (λ_ij):

Independent variables and covariates (x_ij) will be incorporated into the model via the logit function, with population typical population (θ) and individual random effect (η_i) parameters to be estimated:

λ_ij= f(x_ij, θ, η_i)

Covariate effects, and random effects can modulate the predicted probability in a positive or negative direction, with the probability constrained between the values of 0 and 1.

In these analyses it is expected that each individual will contribute only one observation for each outcome endpoint. Thus the individual random effects (η_i) will be fixed at a value of zero and a naïve-pooled data analysis will be conducted. This approach has also been suggested as a check for nonlinear mixed-effects models of dichotomous outcome data[28]. The predicted likelihood (l_ijfor individual i and sampling time j) of the data (y_ij), given the model and parameters will be described by a binomial probability density function:

The likelihood for the entire population PD data set is simply the product of likelihoods across all individuals and data points. Diagnostic plots and the minimum value of the objective function are used to guide model building and assess goodness-of-fit.

Methotrexate (MTX) Model

The administration of methotrexate (MTX) to children with cancer was chosen as our initial setting to develop the first drug dashboard prototype. The difficulty in effectively administering high-dose MTX to oncology patients lie in balancing efficacy and safety. Increased MTX exposure has been shown to be predictive of greater efficacy [29-31], while increased MTX concentrations and prolonged exposure time have also been linked to toxicity [32]. Due to the high inter- and intra-patient variability in methotrexate pharmacokinetics, monitoring of methotrexate plasma concentrations in individual patients has become a standard procedure in order to identify patients at risk of toxicity. Typically, patient plasma concentrations are monitored starting at 24 hours post infusion until MTX plasma concentrations fall below 0.1 to 1 μM [33-37], with adjunct rescue therapy implemented as needed.

The occurrence of methotrexate-induced renal toxicity further complicates chemotherapy administration. Although methotrexate-induced nephrotoxicity is a relatively rare occurrence, it is none-the-less a life threatening complication of methotrexate therapy [38]. Since methotrexate is mainly cleared from systemic circulation via glomerular filtration and renal secretion, delayed drug elimination is a product of this nephrotoxicity. This results in prolonged drug exposure and elevated plasma concentrations. As a result of this increased exposure, severe adverse events such as myelosuppression, mucositis, and hepatitis become more prevalent and severe.

Numerous studies have been conducted to examine the feasibility and reliability of applying Bayesian forecasting approaches to predicting MTX pharmacokinetics. The goals of these studies have been to predict MTX concentrations at later times or the time that MTX concentrations fall below a threshold value [39-41], MTX dose adjustment [42,43], or providing guidance for rescue administration in the case of elevated MTX concentrations for prolonged time periods [44]. The Bayesian prediction models developed thus far have concentrated on those patients with normal renal function, and are not applicable in the case of severe renal dysfunction secondary to high-dose MTX administration.

We have developed a population pharmacokinetic model to implement as a Bayesian predictor of MTX concentrations in patients with normal renal function and MTX-induced renal dysfunction. Plasma concentrations from patients with normal renal function and patients with MTX-induced renal dysfunction were obtained from standard clinical monitoring. The model was constructed from methotrexate dosing histories and monitored drug concentrations in 240 patients. The original dataset contained 2176 observations covering a range of one to 56 observations per patient (an average of 9 observations per patient). The age range was from 1 to 80 years with a weight range of 6.6 to 157 kg. The gender distribution was approximately 48% male (52% female). Hence, our underlying patient diversity allowed us to include and consider relevant size and demographic dependencies. The model was developed using NONMEM version VI[45].

Methotrexate disposition is described by a two-compartment model with first-order elimination. Although MTX clearance changes over time in patients with renal dysfunction, clearance is approximated with a simple model defined by two different clearance distributions for the two populations. Inter-subject variability in PK parameters was expressed using an exponential error model:

where:

P_iis the estimated parameter value for individual i

is the typical population value (geometric mean) of the parameter

η^Piare individual-specific interindividual random effects for individual i and parameter P and are assumed to be distributed: η ~ N(0, ω²) with covariance defined by the inter-individual covariance matrix Ω.

The residual error was described by an additive expression on a log-transformed scale (i.e., proportional error model):

where:

C_ijis the jth measured observation in individual i

is the jth model predicted value in individual i

ε_ijis the additive residual random error for individual i and measurement j and is assumed to be independently and identically distributed

The Bayesian forecasting model utilizes the NONMEM PRIOR subroutine to incorporate population priors into the model. Fixed effects parameters obtained from the final pop PK model were implemented for the initial Bayesian model. Prior distributions of the fixed effects parameters were obtained from the variance-covariance matrix from the final pop PK model as well. Prior distributions for random effects parameters were specified as an inverse Wishart distribution. Clearance was implemented as a mixture model, where a patient is assigned to a population (normal or impaired clearance) based on the probability of that patient belonging to either population given their MTX plasma concentrations. The Bayesian forecasting model was evaluated using MTX plasma concentrations that were not used during model construction. The model reliably predicts future MTX plasma concentrations from two prior concentrations in all patients except a small number who develop renal toxicity at delayed times (> 48 hours). In these patients, the addition of a third concentration after 48 hours increases the precision of the prediction of concentrations at later times.

Dashboard Design and System Architecture

The MTX dashboard was developed based on a three-tier architecture comprising a back end database tier, a business logic middle tier and a data presentation/user interface tier at the front (see Figure 2). The database tier consists of patient records from our electronic medical records system (Sunrise Clinical Manager, SCM) merged with data from patient registration system (IDX), lab data management system (Clarity) and adverse event management system (proprietary). Required data from these systems are extracted and loaded into relational tables within the staging area of the PKB. The data fields are then processed systematically for gaps and manually filled (from patient charts) when any of the missing data are critical for functionality. Such gaps are then noted for future improvements in the data collection process. The level of data validation is minimal and sufficient for testing; a comprehensive data validation approach has been outlined for implementation prior to production release. Various views and summary tables are created from the relational tables for quick retrieval by the application. The current version of the application retrieves data from staging area tables via views and summary tables. Eventually, a multidimensional data mart will permit ad hoc querying and drill down analysis. Upon its completion, data from the staging area will be transformed and loaded into the PKB datamart.

Figure 2. Schematic of three-tier system architecture of hospital pharmacotherapy decision support system comprising a back end database tier, a business logic middle tier and data presentation/user interface front-end tier.

The middle tier consists of rules and processing logic required to collect and prepare data for user presentation (alerts, filters, aggregations, derived values and predictions). Predictions are conducted in an external computational platform – our modeling and simulation (M&S) workbench. This platform can execute code in a variety of languages provided they can run in a batch mode. Of note, the M&S workbench can currently accommodates many of the standard prediction engines used to forecast PK and PK/PD relationships (NONMEM, SAS, SPLUS and R). Details of analytical run processing using NONMEM with the workbench are described below. While the workbench can perform various data processing functions and analytics including generation of plots and figures, it is important to note that all PKB related analytics are gated in the middle tier through logic to ensure that minimally required data sets are available for each patient or sets of patients for meaningful analysis (e.g., appropriate data density to make predictions, etc).

The user interface is a currently web-based and utilizes a combination of HTML, JavaScript and XML content. We are in the process of migrating to an AJAX paradigm and implementing Web 2.0 standards (the new standard for live HTML content). Upon successful transition to Web 2.0, it is possible to readily support more user interface types such as java applet, java application or stay completely within the browser. The Workbench component can co-reside on the same server or installed on another server within the intranet or even hosted anywhere on the internet. The system is designed to transfer data and messages in an authenticated and completely secure manner. When a physician invokes a given forecasting function within PKB, the data required of that patient for the analysis of interest is extracted and written to a flat file in the required application format. The system then edits a previously prepared control file (with job settings and analytical inputs) with necessary changes and makes a call to the Workbench requesting an execution. The communication and data transfer mechanisms are implemented via message queues, thereby ensuring guaranteed delivery, fault tolerance and scalability. The Workbench execution module listening to the queue receives the request and submits the jobs to NONMEM or whatever application has been specified for that analysis by the experts and calls the process manager module to monitor for completion. Upon completion, the process manager calls an application specific parser module to parse and return the results back to the calling application (middle-tier). The middle-tier receives the results and formats it into an XML object and returns the same to the browser for display. If the output of the analysis calls for graphical display of results, the middle-tier sends the unformatted output to the graphing engine and forwards the generated graphs back to the browser for display. The graphs can be setup to support drill downs, mouseovers or invoke further analysis. This ensures that analysis of any kind can be performed via the M&S Workbench to support drug/disease dash boards of varying complexities.

Results

The population pharmacokinetic parameters used as initial priors in the initial Bayesian forecasting algorithm that predicts methotrexate drug concentrations are summarized in Table 2. Diagnostic plots from the current population pharmacokinetic model are shown in Figure 3. These plots indicate that the model is adequate to describe the data. Of course the initial parameter set is simply a reference point for the forecasting routine. As patient-specific data (observed MTX concentration-time data relative to an individual dosing event) is added to the data set, the model is executed again as previously described and updated "priors" are generated incorporating the new subject's observations.

Figure 3. Diagnostic plots from preliminary methotrexate population pharmacokinetic model. (A) Observed versus population predicted concentrations. (B) Observed versus individual predicted concentrations. Open circles represent MTX plasma concentrations from patients predicted to have normal renal function. Open triangles represent patients predicted to have reduced MTX clearance.

Table 2. Current population pharmacokinetic parameter priors used to forecast methotrexate plasma concentrations in pediatric patients

The prototype methotrexate dashboard module is focused on visualizing the current and recent dosing events relative to markers which indicate the potential for drug-induced toxicity. It also forecasts methotrexate exposures within the current dosing regimen to project the potential for toxicity and provide dosing guidance. The user will access the MTX dashboard from our existing medical records system, Sunrise Clinical Manager (SCM). Eventually, the dashboard will be migrated to the EPIC system which is being integrated with the hospital network in phases. From either system, there will be multiple points of entry with the most likely access coming from the patient medical record number. Figure 4 shows screen captures of the current MTX dashboard design. The dashboard contains three tab views (Drug Formulary, Patient, and Patient History). The details of the entire MTX dashboard will be defined in a separate publication. Briefly, the Drug Formulary tab presents formulary data supplied by Lexicomp restructured in a more web-friendly and content rich layout. The Patient History tab provides historical views of previous experience with an agent in the same patient from previous hospital visits. The first panel (Figure 4A) shows the initial entry screen with the patient tab shown. All modeling and simulation is executed via the patient tab. The initial screen (Figure 4A) shows the most recent MTX dose event with the complementary monitored MTX plasma concentrations and safety markers. Based on input from our pediatric oncology community, the dashboard contains a subset of all data captured within SCM with selections from drop down windows possible. Serum creatinine and total bilirubin concentrations are shown plotted with MTX concentrations from the last dose event. Double clicking on any of the three plots will yield an expanded single plot with axes, scale and units shown.

Figure 4. Screen captures from the current MTX dashboard design showing (A) the most recent MTX dose event with the complementary monitored MTX plasma concentrations and safety markers, (B) the MTX exposure projected after the dosing guidance menu button is selected, (C) the view from Figure 4B overlaid against a nomogram used to assess the potential for MTX toxicity with consideration for drug rescue with leucovorin and (D) the update of the model fit when the additional blood collection time points were added to the patient data set.

Figure 4B is the view projected after the dosing guidance menu button is selected. The plot shows the observed 24 and 48 hour MTX plasma concentrations along with the model-predicted MTX exposure (solid line) at these time points and at a subsequent, extrapolated 96 hour point. This extrapolated time point is estimated by calling the MTX population PK model and running the model executable with the patient's previous (observed data) incorporated. The refitted model with updated "patient-specific priors" is then used to project (simulate) the exposure at the 96 hour point, a time when blood collection for MTX plasma concentration determination is normally scheduled in compliance with formulary monitoring practice for MTX.

Figure 4C shows projected view from Figure 4B overlaid against a nomogram used to assess the potential for MTX toxicity with consideration for drug rescue with leucovorin. Several similar nomograms exist for managing MTX drug therapy. Nomograms are aligned to the clinical protocol that the patient is being treated from (protocol is shown in the dashboard in the upper right corner of each screen next to patient demographics. The dashboard contains each of the nomograms used at our institution and so correctly matches the drug exposure views to the nomogram by index to study protocol. Figure 4D illustrates the update of the model fit when the additional blood collection time points were added to the patient data set. The various stages of the MTX dashboard interface including data refresh, model update and output generation are described via the workflow diagram shown in Figure 5. While real-time access is desirable, a scheduled data refresh is more practical. This also removes the burden of data check and model update from the user operation with only calls to produce simulation plots generated by the actual user interface screen.

F igure 5. Workflow of MTX dashboard operation.

Conclusion

The integration of modeling and simulation algorithms with hospital-based networks to guide the pharmacotherapeutic management of individual patients has great potential to improve outcomes. The benefits of such a system should include improved therapy (efficacy), reduced medication errors, greater appreciation for drug interaction potential, earlier identification of toxicity, and earlier guidance on rescue therapy. Our prototype dashboard concept is part of a broader initiative to develop a pediatric knowledgebase of which dashboards are only one component. At present, dashboards for methotrexate, tacrolimus and vancomycin are at various stages of development. Collaborations with other institutions and investigators should allow the generation of additional dashboards beyond our existing capacity. Such systems, as they are developed, will require a level of support beyond which many hospitals are accustomed as mentioned previously. More importantly, they imply a continued effort from clinical pharmacologists and engineers to implement relevant, new research into these systems to ensure that they continue to perform up to expectations and evolve with advances in drug therapy in pediatrics.

MRI: Viewing your brain and other soft tissues

2008-09-24T22:30:00.000-07:00

Magnetic resonance imaging (MRI) creates cross-sectional pictures of your body. Knowing what to expect during the test can help you feel more comfortable.

Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create cross-sectional images of your head and body. Your doctor uses these detailed, clear images to identify and diagnose a wide range of conditions.

Who is it for?

MRI is a noninvasive way for your doctor to examine your body, in particular your brain, neck, spinal cord and soft tissues. MRI often helps with the diagnosis of central nervous system disorders, such as multiple sclerosis, because it produces such high-resolution images of the brain and spinal cord.

MRI is also used to:

Identify brain tumors, strokes and chronic disorders of the nervous system
Reveal brain abnormalities in people with dementia
Diagnose diseases of the pituitary gland
Locate eye or inner ear tissue abnormalities
Identify damage caused by heart attack or heart disease
Detect blood vessel plaques and blockages
Identify and diagnose bone and joint damage
Identify bone and joint infections, injuries, degenerative disorders and tumors
Reveal tumors and functional disorders in organs such as the lungs, liver, pancreas, kidney and spleen
Detect breast cancer
Detect reproductive system and bladder problems

How do you prepare?

Before an MRI exam, eat normally and continue to take your usual medications, unless otherwise instructed. When you report for your exam, you will be asked to complete a screening form. Don't receive an MRI scan if you have an implantable cardioverter defibrillator or a pacemaker. The strong magnetic field produced by the MRI unit may interfere with the function of these devices.

Before undergoing MRI imaging, also tell the technologist if you think you're pregnant, because the effects of magnetic fields on fetuses aren't well understood. Your doctor may recommend postponing the exam or choose an alternative exam.

You may be given a gown and robe to wear or told to wear clothing without metal fasteners, such as sweats. At this time you'll be asked to remove all accessories — watch, jewelry, hairpins. Also remove wigs, dentures and hearing aids.

It's important that you remove all such objects, which may contain metal or electronics, from your body before the exam. Metal objects may interfere with the magnetic field used during the exam, affecting the quality of the MRI images. And the magnetic field may damage electronic items.

Tell the technologist at the time of your exam if you have any metal or electronic devices in your body, such as metallic joint prostheses, artificial heart valves, implanted electronic devices, cochlear implants or magnets in your dentures. The presence of metal in your body may be a safety hazard or affect a portion of the MRI image.

How is it done?

Most MRI machines contain a large magnet shaped like a doughnut or tunnel. You lie on a movable table that slides into the tunnel. The magnetic field aligns atomic particles in some of your cells. When radio waves are broadcast toward these aligned particles, they produce signals that vary according to the type of tissue they are.

The collected signals are interpreted by a computer to create a composite, three-dimensional representation of your body. Any two-dimensional plane (slice) can be electronically created from this representation and displayed on a video monitor for examination. These images can be converted from the screen into photographic film for further viewing and analysis.

What can you expect during the test?

The exam is painless. You don't feel the magnetic field or radio waves. Depending on the part of your body that needs examination, a small device may be placed around the portion being examined to receive the MR signal. Some types of MRI scans can be enhanced by the injection of a contrast material via an intravenous line placed in your hand or arm.

During the MRI scan, the internal part of the magnet produces repetitive tapping, thumping sounds and other noises. Earplugs or music may be provided to help block the noise. A technologist monitors you from another room. You can talk with him or her by microphone. In some cases, a friend or family member may stay in the room with you.

Several sets of images are usually required, each taking from two to 15 minutes to complete. If many sets of images are needed, the entire procedure can last more than an hour. Because movement can blur the resulting images, breathe quietly but comfortably, without moving your head or body.

Some people feel anxious inside a conventional MRI machine. Discuss this with your doctor if you feel this way. He or she can arrange a sedative to help you relax, if necessary. Short-bore MRI machines are shorter and wider, so that more of your body is outside the machine during scans. Some newer MRI machines are open on all sides, but this may reduce image quality.

Results

When the exam is complete, you may be asked to wait until the images are reviewed to make sure that no additional imaging is necessary. You then leave and resume your regular activities. A radiologist reviews the images from your examination and reports the findings to your doctor. Your doctor then discusses any important findings and next steps with you.

Risks

There are no known harmful effects from exposure to the magnetic field or radio waves used in making MRI images. If your scan requires the injection of a contrast material, there is a very small risk of an allergic reaction.

If you are a metalworker, you may need to have an X-ray of your head before undergoing MRI. This will check to see if there are any tiny slivers of metal in your eyes, which could move during the MRI and possibly damage your eyes.

Metal objects are supposed to be kept out of the rooms that house MRI machines. However, accidents can happen and there's a slight chance that you could be injured by a metal object being drawn forcefully toward the strong magnetic field.

Looking ahead

With advancing technology, MRI exams continue to improve. Advances in this area include:

Magnetic resonance angiography. Vascular imaging is one of the newer uses of MRI. Magnetic resonance angiography (MRA) is a noninvasive way to evaluate the arteries and veins throughout your body. This procedure doesn't require threading a catheter into your arteries, as does traditional angiography.
Functional MRI. A development in MRI technology, known as functional MRI, enables researchers to measure split-second nerve cell activity in parts of the brain. Functional MRI can locate areas of the brain that control movement, speech, vision and memory.
Stronger magnets. The strength of the magnetic field of an MRI machine is described by the term "tesla" (T). Most clinical MRI machines contain a 1.5T magnet and some contain 3T magnets. The stronger magnetic field may provide better detail than do conventional machines for some exams.

Find out what a CT scan is, how it's done and how to prepare for one

2008-08-31T20:01:00.000-07:00

A CT scan — also called CT or computerized tomography — is an X-ray technique that produces images of your body that visualize internal structures in cross section rather than the overlapping images typically produced by conventional X-ray exams.

Conventional X-ray exams use a stationary X-ray machine to focus beams of radiation on a particular area of your body to produce 2-D images on film or a digital detector, much like a photograph. But CT scans use an X-ray unit that rotates around your body and a powerful computer to create cross-sectional images, like slices, of the inside of your body.

A conventional X-ray of your abdomen, for example, shows your bones as well as subtle overlapping outlines of your liver, stomach, intestines, kidney and spleen. A CT scan, however, clearly reveals these bones and organs as well as their inner structure and detailed anatomy of your pancreas, adrenal glands, kidneys and blood vessels.

Who is a CT scan for?

Your doctor may recommend a CT scan to help:

Diagnose muscle and bone disorders, such as bone tumors and fractures
Pinpoint the location of a tumor, infection or blood clot
Guide procedures such as surgery, biopsy and radiation therapy
Detect and monitor diseases such as cancer or heart disease
Detect internal injuries and internal bleeding

CT scans can be done even if you have a pacemaker or an internal cardioverter defibrillator — devices implanted in your chest to help regulate your heartbeat. However, if you're pregnant or suspect you might be, tell your doctor. Your doctor may suggest postponing the procedure or choosing an alternative exam that doesn't involve radiation, such as an ultrasound or MRI.

How do you prepare for a CT scan?

CLICK TO ENLARGE

CT scan images of the brain

How you prepare for a CT scan depends on which part of your body is being scanned. You may be asked to remove your clothing and wear a hospital gown. You'll need to remove any metal objects, such as jewelry, that might interfere with image results.

Preparation sometimes involves fasting

Some CT scans require you to drink a contrast liquid before the scan or have contrast injected into a vein in your arm during the scan. A contrast medium blocks X-rays and appears white on images, which can help emphasize blood vessels, bowel or other structures. If your test involves a contrast medium, your doctor may ask you to fast for a few hours before the test.

Depending on the part of your body being scanned, your doctor may ask you to take laxatives, enemas or suppositories, or temporarily modify your diet.

Reactions to contrast medium

Although rare, the contrast medium involved in a CT scan poses a slight risk of allergic reaction. Most reactions are mild and result in hives or itchiness. For people with asthma who become allergic to the contrast medium, the reaction can be an asthma attack.

In rare instances, an allergic reaction can be serious and potentially life-threatening — including swelling in your throat or other areas of your body. If you experience hives, itchiness or swelling in your throat during or after your CT exam, immediately tell your technologist or doctor.

If you've had a reaction to a contrast medium in the past, and you need a diagnostic test that may require a contrast medium again, talk to your doctor. Be sure to let your doctor know if you have kidney problems. Contrast material that's injected into a vein is removed from your body by your kidneys and could potentially cause further damage to your kidneys in some circumstances.

Preparing your small child for a scan

If your infant or toddler is having the test, the doctor may give your child a sedative to keep him or her calm and still. Movement blurs the images and may lead to incorrect results. Ask your doctor how to prepare your child.

How is a CT scan done?

CLICK TO ENLARGE

CT scan image of the abdomen

During a CT scan, you lie on a table inside a doughnut-shaped machine called a gantry. An X-ray tube inside the machine rotates around your body and sends small doses of radiation through it at various angles. As X-rays pass through your body, different tissues absorb different amounts of radiation.

Detectors inside the gantry measure the radiation that has passed through your body and converts it into electrical signals. A computer gathers these signals and assigns them a color ranging from black to white, depending on signal intensity. The computer then assembles the images and displays them on a computer monitor.

What can you expect during a CT scan?

CLICK TO ENLARGE

CT scan slices

Length of the scan

You can have a CT scan in a hospital or an outpatient facility. Expect the exam to last no longer than an hour, depending on the preparation needed and whether it includes the use of a contrast medium. The scan itself may take less than a minute on the newest machines. Most scans take just a few minutes to complete.

How you are positioned

During the CT scan, you lie on a narrow table that slides through the opening of a large device called the gantry. You may lie on your back, side or stomach, depending on the area to be scanned. The table can be raised or lowered. Straps and pillows may help you stay in position. During a CT scan of the head, the table may be fitted with a special cradle that holds your head still.

What the device does

As the X-ray tube rotates around your body, the table slowly moves through the gantry. While the table is moving you may need to hold your breath to avoid blurring the images. You may hear clicking and whirring noises. Each rotation yields several images of thin slices of your body.

The role of the technologist

During this time, a technologist in a shielded room supervises the CT scan and monitors the images as they appear on the computer screen. The technologist can see and hear you, and you can communicate via intercom.

What you may feel

CT scans are painless. If your exam involves use of an intravenous contrast medium, you may feel a brief sensation of heat or experience a metallic taste in your mouth. If you receive the contrast medium through an enema — to help highlight your lower gastrointestinal region — you may feel a sense of fullness or cramping.

Back to normal

After the exam you can return to your normal routine. If you were given a contrast medium, your doctor, a nurse or the CT technologist performing the scan may give you special instructions. You may be asked to wait for a short time in the radiology department to ensure that you feel well after the exam. After the scan, you'll likely be told to drink lots of fluids to help your kidneys remove the medium from your body.

During your small child's exam

If an infant or small child is having the CT scan, you may be allowed to stay with your child during the test. If so, you may be asked to wear a lead apron to shield you from X-ray exposure.

Results of a CT scan

CT images are stored as electronic data files and usually reviewed on a computer. A radiologist interprets these images and sends a report to your doctor.

Risks of a CT scan

CT scan risks are similar to those of conventional X-rays. During the CT scan, you're briefly exposed to radiation. But doctors and other scientists believe that CT scans provide enough valuable information to outweigh the associated risks. Be sure to inform your doctor if:

You're pregnant. If you're pregnant, your doctor may recommend another type of exam to reduce the possible risk of exposing your fetus to radiation.
You have asthma or allergies. If you have had a prior reaction to contrast media or have asthma or allergies and your CT scan requires a contrast medium, there's an increased risk of a reaction to the contrast medium.
You have certain medical conditions. Diabetes, asthma, heart disease, kidney problems or certain thyroid conditions may increase your risk of a reaction to contrast media.

Alternative Fuel

2008-07-07T05:45:00.000-07:00

Are these Alternative Fuel plans Scams?

I just like you have seen all the ads saying run your car on water.

A car cannot run on water alone!

But they can run partially on the gasses that water contains. Yes that’s right you can convert water to hydrogen and oxygen and use the gasses to assist the running of your car and therefore reduce your fuel bill.

The Simple Facts.

Cars will not run on water alone.
Water is also known as h2o (one part hydrogen and 2 parts oxygen)
You won’t produce enough hydrogen to run your car solely on hydrogen.
Your car will still require petrol (gasoline) to run.
You can reduce your fuel costs.

We have reviewed all the most popular products available for download.
All products that we looked at do work.
All products vary in design and all will produce hydrogen.
Basically all the products are exactly the same and produce the same results.
The only difference is the price and quality of the instructions supplied.

Anda Ingin S2 ke Luar Negeri?

2008-06-25T18:35:00.000-07:00

Jika Anda ingin ambil S2 ke luar negeri tentunya banyak hal yang harus dipersiapkan. Salah satunya adalah syarat nilai TOEFL minimal yang harus dicapai. Memang ada bermacam syarat nilai TOEFL minimal yang berbeda tergantung tujuan perguruan tinggi mana yang akan dituju. Untuk membantu Anda dalam mempersiapkan hal ini, berikut ada beberapa link free download yang dapat Anda klik.
Semoga sukses.

TOEFL Exam Essentials

TOEFL Exam Success

TOEFL GRAMMAR

Dictionary of American Slang and Colloquial Expressions

Bux.to

2008-06-16T23:06:00.001-07:00

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G-CCNA 640-801 Discovery

2008-06-16T00:30:00.000-07:00

G-CCNA 640-801 Discovery

1. What was one of the most important reasons the International Organization for Standardization released the OSI model?

A. Users could access network server faster.
B. Different vendor?s networks could work with each other.
C. The industry could create a standard for how computers work.
D. The network administrator could increase the overall speed of their network.

Ans:B

2. You have just entered the command copy running-config startup-config command to save your configuration so that if the router is rebooted it will keep your configuration. Which type of router memory normally stores the startup configuration?
A. RAM
B. ROM
C. FLASH
D. NVRAM

Ans:D

3. Assuming a default subnet mask which two pieces of information can be derived from the IP address 131.107.2.200? (Choose Two)
A. It is a Class C address
B. It is a Class B address
C. The network address is 131.0.0.0
D. The network address is 131.107.2.0
E. The host portion of the address is 2.200

Ans:B,E

4. Comparing half-duplex Ethernet to full-duplex Ethernet which of the following are true? (Choose two.)
A. Shared collision domain.
B. Private collision domain.
C. Higher effective throughput.
D. Lower effective throughput.
E. Private broadcast domain.

Ans:A,D

5. You are configuring an old router that is running an old IOS that does not support inverse arp. If a router does not support inverse arp how can you setup this frame relay connection?
A. Configure static maps.
B. Define an IP address.
C. Disable DHCP on the Frame Relay router.
D. Configure a static route to the remote network.

Ans:A

6. Given the following criteria for granting access from a remote site to your LAN: Restrict access on interface E1 E1=207.87.81.173 Deny access to telnet, FTP, SNMP Allow all other types of operations.

Which line should come last in configuring your access list?

A. Access-List 101
B. Access-List 101 deny E0 telnet FTP
C. Access list 101 allow all except FTP telnet
D. Access list 101 permit IP 0.0.0.0 255.255.255.255 any
E. Access List 101 deny IP 207.87.81.173 TCP EQ 20 21 23

Ans:D

7. Most networks are often described as using either 10BaseT or 100BaseTX media. What does the 'Base' in these media types mean?
A. It describes the signaling method for communication on the network.
B. It refers to the type of media used in the network.
C. It relates to the speed of transmission of network signals.
D. It defines the allowable length of media that can be used.
E. It defines half-duplex or full-duplex operation.

Ans:A

8. To configure a Frame Relay Router with subinterfaces on interface Serial 3. Which subinterface number could you use for this configuration?
A. 1 and 2.
B. 3.2 and 3.3
C. 1 and 1.1
D. 3.1a and 3.1b.

Ans:B

9. Using a protocol analyzer we noticed sustained, heavy collisions in our CSMA/CD LANs. What are some possible affects could this have our LAN? (Choose three.)

A. Increased broadcast traffic.
B. Delay.
C. Low throughput.
D. High throughput.
E. Congestion.
F. Higher bandwidth.

Ans:B,C,E

10. Which of the following are layer 7 protocols? (Choose two.)
A. Ping
B. Telnet
C. FTP
D. TCP
E. IP

Ans:B,C

192. What is the total bandwidth of an ISDN BRI circuit?
A. 54 kps
B. 64 kps
C. 112 kps
D. 128 kps
E. 144 kps

Ans:E

197. Which one of the layers of the seven layer OSI model uses positive acknowledgement and retransmission to ensure reliable delivery?
A. Application
B. Presentation
C. Session
D. Transport
E. Data link
F. Physical

Ans:D

198. To distinguish between each PVC what does the Frame Relay switch use?
A. Data link connection identifier (DLCIs)
B. CNs
C. FECNs
D. Local management interface LMI

Ans:A

200. RouterA has two redundant paths serial links to RouterB. RouterA and RouterB are only using the IPX protocol. You have noticed that RouterA is not using both paths to get to RouterB. Which command can you enter to enable load balancing across those serial links?
A. ipx load-balance.
B. ip maximum-paths 2.
C. ipx maximum-paths 2.
D. ipx load-share.

Ans:C

201. Julia telnets to a pc on a remote subnet, which MAC address will be present in the ARP table when you issue the show arp command?
A. MAC address of the destination host Ethernet port.
B. MAC address of the local router Ethernet port.
C. MAC address of the destination router Serial port.
D. MAC address of the local router Serial Port.

Ans:B

203. You have just entered the command: Superhero(config-line)#logging sync Cisco IOS allows which keystroke(s) to complete the syntax of a partially entered command.

Which keystroke(s) did you use to complete the above command above to the completed following command: Superhero(config-line)#logging synchronous ?

A. Ctrl+shift+6 then x.
B. Ctrl+Z
C. TAB
D. /? E. Shift

Ans:C

204. How do you change the Console password on the Sonic router to "cisco"?
A. Sonic(config)#line con 0 Sonic(config-line)#login Sonic(config-line)#password cisco
B. Sonic(config)#line con 0 Sonic(config-line)#login Sonic(config-line)# password Cisco

Ans:A

205. Christopher issues a show cdp neighbor command from Router
A. RouterA has connections to RouterB and RouterC through the serial s0 and s1. Which three pieces of CDP information about neighboring routers are displayed on your console terminal? (Choose three)

A. The neighboring router?s host name.
B. The neighboring router?s hardware platform.
C. Up to one address for each protocol supported.
D. Up to two addresses for each protocol supported.
E. As many addresses as are configured for each protocol supported.

Ans:A,B,C

206. Aaron is troubleshooting a problem on his network he issues the command ping 10.0.0.2 to test the physical connectivity between two devices? Which type of ICMP messages was carried in the IP datagrams?
A. ICMP echo request.
B. Information request.
C. Timestamp reply.
D. Redirect.
E. Source quench.

Ans:A

207. All TCP/IP hosts implement the ICMP protocol?
A. TRUE
B. FALSE

Ans:A

208. Your company has decided to use IGRP instead of RIP as the routing protocol. They want to use autonomous system number 130. Which is the correct command for this installation?
A. Router(config)# igrp 130
B. Router(config)# network 130
C. Router(config)# router igrp 130
D. Router(config)# enable igrp 130

Ans:C

209. To govern the flow of data between two devices, TCP uses a flow control mechanism. Which one of the following is true about this mechanism?
A. TCP makes no effort to check for lost or duplicate data packets.
B. The application layer must sequence data packets when using TCP.
C. TCP controls the flow of UDP data through negative acknowledgements NAK.
D. TCP is a connection-oriented protocol that acknowledges receipt of data packets and is considered reliable.

Ans:D

210. What are the benefits of replacing a hub with a bridge and segmenting the network?
A. It increases the number of collision domains.
B. It decreases the number of collision domains.
C. It increases the number of broadcast domains.
D. It decreases the number of broadcast domains.

Ans:A

211. Your company is considering purchasing a new accounting software application from ABC accounting company. The ABC accounting company has decided to come in and let you install a demo copy of their software so that you can test it in your network with a few hosts. The server and the hosts that will connect to this server will need a 10Mbps connection. Your company is currently using a hub. Your company has decided to use this new accounting software application. However when you ran your packet analyzer you noticed the rest of the hosts on your network that are not using this application have a bandwidth problem with the new accounting system installed. Since your company has decided to use this new application they would like you to resolve the bandwidth problem. What is the most economical decision would you implement for resolving this problem?

A. Install new 100 Mbps switches, and change all hosts? NIC to 100 Mbps.
B. Segment network with router, and place all testing hosts and the new server into a separate subnet (network).
C. Add a Bridge and separate the two networks.

Ans:B

212. What must you do to test connectivity on a dial on demand routing (DDR) link?
A. Increate the idle import parameter.
B. Send interesting traffic across the link.
C. Switch
D. Repeater

Ans:B

213. Cisco supports IPX traffic using different encapsulation types can go over the same interface.
A. TRUE
B. FALSE

Ans:A

216. What is the protocol and what is the second part of the following network address: 10.0.0.254 mask 255.0.0.0 ? (Choose all that apply.)
A. IPX MAX address.
B. IP Class C director broadcast.
C. Private IP address node number.
D. Public IP address directed broadcast.
E. Private IP address directed broadcast.

Ans:c

217. Using a class C address you need five subnets with a maximum of 17 hosts on each of these subnets. Which subnet mask would you use?
A. 255.255.255.192
B. 255.255.255.224
C. 255.255.255.240
D. 255.255.255.248

Ans:B

218. Which layer of the OSI model handles data translation, code formatting, and encryption occur?

A. Physical
B. Data link
C. Network
D. Transport
E. Session
F. Presentation

Ans:F

219. RouterA is directly connected to RouterB. On RouterA you shutdown the interface that is going to RouterB (you put it administratively down). If you issue the command show interface on RouterB what output status would you see on the interface that is connected to RouterA?
A. Interface is down, line protocol is down.
B. Interface is down, line protocol is up.
C. Interface is up, line protocol is down.
D. Interface is up, line protocol is up.

Ans:A

220. Using a protocol analyzer you determine your LAN traffic is experiencing congestion. What could be some possible causes for a congested network? (Choose four.)
A. Too many hosts in a broadcast domain.
B. Full Duplex operation.
C. Broadcast storms.
D. Multicasting.
E. Segmentation.
F. Low bandwidth.

Ans:A,C,D,F

221. Looking at this address 255.255.255.255 which one of the following is true?
A. IP, a flooded broadcast.
B. IP, a directed broadcast.
C. IPX, a flooded broadcast.
D. IPX, a remote directed broadcast.

Ans:A

222. IP addresses use hierarchical numbering. What portion of the address that will identify the network number?
A. Subnet Mask.
B. Dots between octets.
C. Class of first octet.
D. Assignments of DHCP.
E. Address Resolution Protocol.

Ans:C

223. Which wide are network technology was designed to use high-performance digital lines and is packet switched?
A. FDDI
B. ISDN
C. ATM
D. Frame Relay

Ans:D

224. Which of the following are functions that occur at the transport layer of the OSI model? (Choose three)
A. Route selection-IP
B. Sliding window-UDP
C. Well known ports-IP
D. Route validation-ICMP
E. Connection oriented-TCP/IP
F. Three way handshake TCP/IP
G. No acknowledgement-UDP

Ans:E,F,G

226. Which wide area network technology was designed to work with traditional POTS lines and provide SOHO?s and users with a higher speed digital dial-up service?
A. Frame relay
B. X.25
C. ATM
D. ISDN

Ans:D

227. Using the following address and subnet mask 195.106.14.0/24 what is the total number of networks and the total number of host per network?

A. 1 network with 254 hosts.
B. 2 networks with 128 hosts.
C. 4 networks with 64 hosts.
D. 6 networks with 30 hosts.

Ans:A

228. Exhibit: You are configuring R2 so that it can communicate with R1 on serial port s0. What encapsulation should you use on s0 to setup this IPX network?

A. SAP
B. HDLC
C. ARPA
D. Novel Ether

Ans:B

230. Exhibit You want to create a sub interface on serial 0 on Router R2. Which of the following is the correct syntax to create this sub interface 2?

A. Interface s0.2 point-to-point.
B. Interface 2s0 point-to-point.
C. Subinterface 2s 0 point-to-point.
D. Interface s0 sub2 point-to-point.
E. Interface s0.1 point-to-point sub2.

Ans:A

231. Exhibit: You are configuring the IPX encapsulation between RouterA and RouterB. This connection will be using the S0/0 port on RouterA to S0/0 on RouterB. Which encapsulation type should be used for the S0/0 port of RouterB?

A. SAP
B. HDLC
C. ARP
D. NOVELLETHER

Ans:B

232. Exhibit:

You are configuring R3 so that it can communicate with R2 on Ethernet port e1. What encapsulation should you use on s0 to setup this IPX network?

A. SAP
B. HDLC
C. ARPA
D. Novell-Ether

Ans:D

233. Which one of the following characteristics about Ethernet Switches is true?

A. Symmetric switching allows connection between ports of unlike bandwidth and does not require memory buffering.
B. Memory buffering is used to prevent a bottleneck when ports of different bandwidth are connected on a symmetric switch.
C. The latency can be reduced if the switch utilizes the store and forward method of switching. Store and forward is better for error detection.
D. The cut-trough method of switching is faster because the switch forwards the packet to the destination as soon as it reads the destination address.

Ans:D

248. Exhibit:

Frame Relay switch maps the DLCIs between Router A to Router B to create a PVC. Which statement below correctly identifies the reference point between the local router and the Frame Relay switch to which it is connected?

A. Locally significant DLCI
B. Globally significant DLCI
C. Locally significant LMI
D. Globally significant LMI

Ans:A

249. You have a leased line configured at a small office that connects to the corporate office. You company would also like to have a backup incase the lease line goes down. Which WAN service would you most likely choose to backup the leased line?
A. Frame relay with SVC
B. Dedicated serial line
C. ISDN with DDR
D. ATM

Ans:C

250. What are the advantages of using the OSI layered network model? (Choose three.)
A. Allows multiple-vendor development through standardization of network components.
B. Creates a list of communication rules that all companies must implement to get onto the Internet.
C. Allows various types of network hardware and software to communicate.
D. Prevents changes in one layer from affecting other layers, so it does not hamper development.
E. Allows companies to develop proprietary interfaces.

Ans:A,c,D

122. You just purchased a brand new Cisco 2621 Router and now would like to configure password protection on this router. Which of the following are true regarding passwords on this router?
A. All passwords can be encrypted.
B. All passwords can be entered using the set-up dialogue.
C. A password can be set before a user can enter the privileged mode.
D. A password can be set for individual lines.
E. TACACS or Radius password authentication can be used.

Ans:A,C,D,E

124. There are three major groups of routing protocols: distance-vector protocols, link-state protocols, and hybrid protocols. Select two valid statements regarding routing protocols? (Choose two)
A. Distance vector protocols send the entire routing table to directly connected neighbors.
B. Link state protocols send the entire routing table to all routers in the network.
C. Distance vector protocols send updates about directory connected neighbors to all networks listed in the routing table.
D. Link state protocols send updates containing the state of their own links to all other routers on the network.

Ans:A,D

125. Which of the following ranges are used for IPX standard access lists?
A. 100 - 199
B. 600 - 699
C. 800 - 899
D. 1000 - 1099

Ans:C

126. ExhibitRouter1#show access-list

Extended IP access list 135 deny tcp any 131.107.0.0 0.0.255.255 eq 53 deny tcp any any eq telnet Router1#show ip interface e0 Ethernet0 is up, line protocol is up Internet address is 172.17.9.60/24 Broad address is 255.255.255.255 Address determined by setup command MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is enabled Outgoing access list is 135 Inbound access list is not set

Proxy ARP is enabled Security level is default Split horizon is enabled Rest of configuration omitted.

You have created an Extended IP access list. Now you apply the access list to Ethernet 0.

What is the result of this action?

A. Only e-mail and telnet access will be permitted out of Ethernet 0.
B. All hosts on the 172.30.24.64 network will be permitted e-mail and telnet access.
C. All TCP protocols will be permitted out of Ethernet 0 except e-mail and telnet.
D. All IP traffic out of Ethernet 0 will be denied.
E. The access-list is numbered incorrectly and will fail.

Ans:D

50. To configure Router1 for operation in a Frame Relay environment, one of the recommended items to configure is the IGRP metric for the speed of the link. What command should you use?
A. Router1(config)# IGRP metric 36k
B. Router1(config)# bandwidth 36
C. Router1(config-if)# metric 36k
D. Router1(config-if)# bandwidth 36

Ans:D

128. You have just created an IP extended access list and now wish to apply this to an interface. Which command will allow you to apply the list to an interface?
A. Permit access-list 101 out
B. Ip access-group 101 out
C. Apply access-list 101 out
D. Access-class 101 out
E. Ip access-list e0 out

Ans:B

129. Which of the following devices operate at Data Link layer of the OSI model? (Choose two)
A. Router
B. SMTP server
C. Transceiver
D. Switch
E. Bridge
F. Hub

Ans:D,E

130. You have been called in to fix a router that is having security issues. The router has an access list configured on it but the list does not seem to be working. What command can you use to see if the access list has been applied to an interface?
A. Show access-list.
B. Show ip route.
C. Show ip interface.
D. Show interface.
E. Show interface list.

Ans:C

131. User Datagram Protocol is a Connectionless transport layer protocol in the TCP/IP protocol stack. UDP is defined in RFC 768. Which of the following are generally considered to be characteristics of UDP? (Choose two.)
A. Non-reliable.
B. Reliable.
C. Less bandwidth-intensive.
D. Handshaking.

Ans:A,C

132. How many bits are used for a MAC address and how is number expressed?
A. 24 bits expression as a decimal number.
B. 24 bits expression as a hexadecimal number.
C. 36 bits expression as a binary number.
D. 48 bits expression as a decimal number.
E. 48 bits expression as a hexadecimal number.

Ans:E

133. Which command will provide you with information regarding the Layer 3 IP address of a directly connected neighbor?

A. Show ip interface
B. Show cdb neighbors
C. Show cdp neighbors detail
D. Show ip route
E. Show ip link status
F. Telnet

Ans:C

134. What is the bit pattern for the first octet of a class B network address 129.107.0.0?
A. 0xxxxxxx
B. 10xxxxxx
C. 110xxxxx
D. 1110xxxx
E. 11110xxx

Ans:B

135. Gail was working on your Cisco router while you were at lunch. Which command will display the last commands Gail entered?
A. Control header.
B. Show buffer.
C. Show history.
D. Show history buffer.

Ans:C

136. You are the network administrator of the ABC Tire Company. You receive a call from a user who is unable to reach a server at a remote server 10.0.5.250/240. Using VNC (Virtual Network Computing) you connect to the user?s computer and discover the following information:Local PC ? 10.0.3.35/24 Default gateway ? 10.0.3.1 Remote server ? 10.0.5.250/240 You then conduct the following tests from the user?s PC: ping 127.0.0.1 ? successful ping 10.0.3.35 ? successful ping 10.0.3.1 ? successful ping 10.0.5.250 ? unsuccessful

Which of the following problems would create the test results listed above?

A. TCP/IP not correctly installed.
B. Local physical layer problem.
C. Local NIC not functioning.
D. Remote physical layer problem.

Ans:D

137. Which are the following are considered ISDN benefits? (Choose four)
A. Full time connectivity across the ISDN supported by Cisco IOS routing using dial on demand routing DDR.
B. Small office and home office sites can be economically supported with ISDN basic rate interface BRI services.
C. ISDN replaces signaling system ss7 in the public switch telephone network PSTN backbone.
D. ISDN can be used as a backup service for a lease line connection between the remote and central offices.
E. Modem racking and cabling can be eliminated by integration with digital modem cards on Cisco IOS network access servers NAS.

Ans:A,B,D,E

61. You are the network administrator of the Sonic Water Company. One of your users is unable to reach the company?s web site that is hosted at a remote site. Looking at the personal computer you discover the following information:Local PC ? 10.0.3.35/24 Default gateway ? 10.0.3.1 Remote server ? 10.0.5.250/240

You then conduct the following tests from the offending local PC: ping 127.0.0.1 ? successful ping 10.0.3.35 ? successful ping 10.0.3.1 ? unsuccessful ping 10.0.5.250 ? unsuccessful

Which of the following problems would create the test results listed above?

A. TCP/IP not correctly installed.
B. Local physical layer problem.
C. Local NIC not functioning.
D. Remote physical layer problem.

Ans:B

Turn any car into a plug-in hybrid for $3,300

2008-05-25T04:44:00.000-07:00

Toyota (Prius) and GM (the Volt and the Vue) seem to be in a race as to who will provide the first mass-produced plug-in-hybrid electric vehicle (PHEV). The backfit market is building options coming for plug-in conversions for existing hybrids.

But what about the tens of millions of normal, internal-combustion engines out there? Is there any hope for them?

If Poulsen Hybrid is to be believed, the answer is a resounding "yes!" The Poulsen Hybrid Power Assist System "creates a PHEV by retrofitting electric motors, DC motor controllers, storage batteries and an on-board charger to a conventional new or used automobile."

This electric system would be used for maintaining speed, after acceleration:

The development is based on the observation that only 10-15 horsepower is required to propel a compact or mid-size automobile along a level road at a steady 60-70 mph. leading to the conclusion that this relatively small amount of electric power would be able to cope with 70-85% of normal driving, only aided by the combustion engine during start up and when extra energy is required for acceleration and hill climbing.

The systems puts hybrid electric motors on the outside of the rear wheels with an on-board charger.

Poulsen's system is expected to debut on the market next month -- $3,300 for purchase and $600 for professional installation.

Mark me intrigued but questioning. For example,

This system doesn't have regenerative braking, thus one is simply trading the cost of gasoline for electricity. At $4,000, a break-even point comes well after saving 1,000 gallons of gasoline. Thus, how much gasoline is really saved as this system basically moves the ICE to idling while the electricity handles acceleration.
The addition of this system outside the car will increase wind drag. A meaningful amount? Don't know.
Also, some basic safety questions must arise. What are the implications for adding these systems outside the car?

But I'm still pretty intrigued with this ingenious approach to tackling the challenges of the huge existing fleet of internal-combustion engine vehicles and moving miles from gasoline to electricity.

Widespread adoption of PHEVs can reduce GHG emissions from vehicles by more than 450 million metric tons annually in 2050 -- equivalent to removing 82.5 million passenger cars from the road.

There is an abundant supply of electricity for transportation, and a 60% U.S. market share for PHEVs would use seven to eight percent of grid-supplied electricity in 2050. PHEVs can improve nationwide air quality and reduce petroleum consumption by 3 million to 4 million barrels per day in 2050.

But do we have 43 years to do this? Why not start with today's automobiles

Hat tip to AutoBlogGreen.

High gas prices? Take the bus instead

2008-05-25T04:10:00.000-07:00

Newspapers around the U.S. are reporting a jump in ridership on public transit lines this spring. According to Grist.org, from January to March of this year, transit systems gained between 7 and 28 percent more passengers than last year.

Further reading found that cities around the country are experiencing a bus boom. Triangle Transit which serves the Raleigh, Chapel Hill, and Durham areas in North Carolina, reports that ridership is up 20 percent from April 2007. In California's capitol, the Sacramento Regional Transit District, also saw a 20 percent leap in bus and light-rail use this spring compared to last year.

Boston, Los Angeles, Denver, Minneapolis/St. Paul, Philadelphia, New York City, and south Florida have all seen spikes in public transportation use recently. And everyone says high gas prices are the reason.

A New Jersey administrator explained that his monthly train pass costs $77 -- far less than the $400 in gas his 72-mile roundtrip commute required. In Richmond, Virginia, a worker estimated that he saves $10 per day by taking the bus to work instead of commuting by car.

Even in the pricey San Francisco Bay Area, it pays to jump the train. One mechanical engineer said he was spending $400 a month in gas for his 60-mile commute, but he switched to a $225 train pass. Now he leaves the stressful traffic behind and snoozes during the morning rush-hour.

Want to save money and live lighter on the planet, plus get some time to decompress, read a book, or even get a little work done on your laptop or BlackBerry? Look for bus routes and commuter trains in your city. Check out this public transportation map for links to most every system in the country.

About.com sums up the concrete benefits of public transit. An average family could save $6,200 annually by using public transit. Riding the bus is 79 times safer than riding in a car. American dependence on foreign oil would decrease 40 percent if just one in 10 citizens took the bus or train daily. And even at current ridership levels, public transit saves about 1.5 million tons of carbon dioxide every year.

Another option that some folks find more flexible is carpooling. If you work at a midsized or larger company, look for coworkers who live nearby or on similar commute routes. Then share the ride and split gas costs. In many cities, you can use carpool lanes that will cut the commute time dramatically.

Even if you work at a small company, you can buddy up with workers at nearby employers. Perhaps there's a vanpool for your employment region.

The Rideshare Directory lists sites that help you set up a carpool. Try E-rideshare, Carpoolworld, or Vanpool, just to name a few. Some regions have specialized systems, like Rideshare 511 in the San Francisco Bay Area -- search the Web for your own town.

You don't have to pay $4 for a gallon of gas. Share the ride with others, and you'll save a bundle. And you'll cut your carbon footprint too.

CCNA Discovery 1 - Module 3 Exam Answers V.4

2008-05-16T14:44:00.000-07:00

CCNA Discovery 1 - Module 3 Exam Answers V.4

1. Which term is used to describe the process of placing one message format into another format so that the message can be delivered across the appropriate medium?
• flow control
• encapsulation
• encoding
• multicasting
• access method

2. Refer to the graphic. Five PCs are connected through a hub. If host H1 wants to reply to a message from host H2, which statement is true?
• H1 sends a unicast message to H2, but the hub forwards it to all devices.
• H1 sends a unicast message to H2, and the hub forwards it directly to H2.
• H1 sends a broadcast message to H2, and the hub forwards it to all devices.
• H1 sends a multicast message to H2, and the hub forwards it directly to H2.

3. Which two statements concerning networking standards are true? (Choose two.)
• adds complexity to networks
• encourages vendors to create proprietary protocols
• provides consistent interconnections across networks
• ensures that communications work best in a single-vendor environment
• simplifies new product development

4. What does the 100 mean when referencing the 100BASE-T Ethernet standard?
• type of cable used
• type of data transmission
• speed of transmission
• type of connector required
• maximum length of cable allowed

5. Which address does an NIC use when deciding whether to accept a frame?
• source IP address
• source MAC address
• destination IP address
• destination MAC address
• source Ethernet address

6. Which type of address is used in an Ethernet frame header?
• logical addresses only
• IP addresses only
• MAC addresses only
• broadcast addresses only

7. What is the function of the FCS field in an Ethernet frame?
• detects transmission errors
• provides timing for transmission
• contains the start of frame delimiter
• indicates which protocol will receive the frame

8. What is the purpose of logical addresses in an IP network?
• They identify a specific NIC on a host device.
• They are used to determine which host device accepts the frame.
• They provide vendor-specific information about the host.
• They are used to determine the network that the host is located on.
• They are used by switches to make forwarding decisions.

9. Which device accepts a message on one port and always forwards the message to all other ports?
• modem
• switch
• router
• hub

10. Which two networking devices are used to connect hosts to the access layer? (Choose two.)
• router
• hub
• switch
• server
• computer

11. Host A needs to learn the MAC address of Host B, which is on the same LAN segment. A message has been sent to all the hosts on the segment asking for the MAC address of Host B. Host B responds with its MAC address and all other hosts disregard the request. What protocol was used in this scenario?
• ARP
• DHCP
• DNS
• WINS

12. A switch receives a frame with a destination MAC address that is currently not in the MAC table. What action does the switch perform?
• It drops the frame.
• It sends out an ARP request looking for the MAC address.
• It floods the frame out of all active ports, except the origination port.
• It returns the frame to the sender.

13. What is a benefit of having a router within the distribution layer?
• prevents collisions on a local network
• keeps broadcasts contained within a local network
• controls which hosts have access to the network
• controls host-to-host traffic within a single local network

14. Refer to the graphic. What does the router do after it determines that a data packet from Network 1 should be forwarded to Network 2?
• It sends the data packet as it was received.
• It reassembles the frame with different MAC addresses than the original frame.
• It reassembles the data packet with different IP addresses than the original data packet.
• It reassembles both the packet and the frame with different destination IP and MAC addresses.

15. Which table does a router use to make decisions on where a data packet is to be sent?
• ARP table
• routing table
• network table
• forwarding table

16. If the default gateway is configured incorrectly on the host, what is the impact on communications?
• The host is unable to communicate on the local network.
• The host can communicate with other hosts on the local network, but is unable to communicate with hosts on remote networks.
• The host can communicate with other hosts on remote networks, but is unable to communicate with hosts on the local network.
• There is no impact on communications.

17. What device is typically used as the default gateway for a computer?
• a server hosted by the ISP
• the router interface closest to the computer
• a server managed by a central IT department
• the switch interface that connects to the computer

18. If a router receives a packet that it does not know how to forward, what type of route must be configured on the router to prevent the router from dropping it?
• dynamic route
• default route
• destination route
• default destination

19. Which two items are included in a network logical map? (Choose two.)
• naming scheme
• IP addressing scheme
• length of cable runs
• physical location of networking devices
• specific layout of interconnections between networking devices and hosts

20. An integrated router can normally perform the functions of which two other network devices? (Choose two.)
• NIC
• switch
• e-mail server
• application server
• wireless access point

21. What is a reason for disabling simple file sharing?
• It enables the user to map a remote resource with a local drive.
• It enables the user to share all files with all users and groups.
• It enables the user to share printers.
• It enables the user to set more specific security access levels.

CCNA Discovery 1 - Module 4 Exam Answers V.4

2008-05-16T14:42:00.000-07:00

CCNA Discovery 1 - Module 4 Exam Answers V.4

1. Which definition describes the term Internet?
• a group of PCs connected together on a LAN
• a group of PCs connected together by an ISP
• a network of networks that connects countries around the world
• a worldwide collection of networks controlled by a single organization

2. What type of connection point is a point of presence (POP)?
• between a client and a host
• between two local networks
• between a computer and a switch
• between an ISP and a home-based LAN

3. What is the term for the group of high-speed data links that interconnect ISPs?
• Internet LAN
• ISP backbone
• Internet gateways
• Internet providers
• Internet backbone

4. Which device can act as a router, switch, and wireless access point in one package?
• hub
• bridge
• modem
• repeater
• ISR

5. What are three characteristics of business class ISP service? (Choose three.)
• fast connections
• extra web space
• free Windows upgrade
• cheapest cost available to all users
• additional e-mail accounts
• replacement hardware at no cost

6. What is a major characteristic of asymmetric Internet service?
• Download speeds and upload speeds are equal.
• Download speeds are slower than upload speeds.
• Upload speeds and download speeds are different.
• Upload speeds and download speeds are irrelevant.

7. Which three elements are required to successfully connect to the Internet? (Choose three.)
• an IP address
• file sharing enabled
• a network connection
• server services enabled
• access to an Internet service provider
• an address obtained directly from the RIR

8. What term describes each router through which a packet travels when moving between source and destination networks?
• NOC
• ISP
• hop
• segment

9. What does the tracert command test?
• NIC functionality
• the ISP bandwidth
• the network path to a destination
• the destination application functionality

10. What type of end-user connectivity requires that an ISP have a DSLAM device in their network?
• analog technology
• cable modem technology
• digital subscriber line technology
• wireless technology

11. Why would an ISP require a CMTS device on their network?
• to connect end users using cable technology
• to connect end users using analog technology
• to connect end users using wireless technology
• to connect end users using digital subscriber line technology

12. Refer to the graphic. What type of cabling is shown?
• STP
• UTP
• coax
• fiber

13. Refer to the graphic. What type of cabling is shown?
• STP
• UTP
• coax
• fiber

14. Which two places are most appropriate to use UTP cabling? (Choose two.)
• between buildings
• in a home office network
• where EMI is an issue
• in a cable TV network
• inside a school building
• in a manufacturing environment with hundreds of electrical devices

15. What does adherence to cabling standards ensure?
• data security
• no loss of signal
• no electromagnetic interference
• reliable data communications

16. Refer to the graphic. What type of cable is shown?
• crossover
• eight coax channels
• multimode fiber
• single-mode fiber
• straight-through

17. What connector is used to terminate Ethernet unshielded twisted pair (UTP) cabling?
• ST
• BNC
• RJ-11
• RJ-45

18. Which two characteristics describe copper patch panels? (Choose two.)
• uses RJ-11 jacks
• uses RJ-45 jacks
• supports only data transmissions
• allows quick rearrangements of network connections
• forwards transmissions based on MAC addresses

19. What are two advantages of cable management? (Choose two.)
• requires no preplanning
• aids in isolation of cabling problems
• protects cables from physical damage
• provides compliance with future standards
• provides a short-term solution for cable installation

20. What are two common causes of signal degradation when using UTP cabling? (Choose two.)
• installing cables in conduit
• having improper termination
• losing light over long distances
• installing low quality cable shielding
• using low quality cables or connectors

21. What are three commonly followed standards for constructing and installing cabling? (Choose three.)
• pinouts
• cable lengths
• connector color
• connector types
• cost per meter (foot)
• tensile strength of plastic insulator

CCNA Discovery 1 - Module 5 Exam Answers V.4

2008-05-16T14:39:00.000-07:00

CCNA Discovery 1 - Module 5 Exam Answers V.4

1. How large are IPv4 addresses?
• 8 bits
• 16 bits
• 32 bits
• 64 bits
• 128 bits

2. Refer to the graphic. A user at the workstation cannot connect to the server. All cables have been tested and are working and all devices have IP addressing. However, the user cannot ping the server. What is causing the problem?
• The router interface does not have a default gateway.
• The switch does not have an IP address and default gateway.
• The workstation and server are on different logical networks.
• The workstation does not know the MAC address of the switch.

3. Which part of an IP address identifies a specific device on a network?
• first two octets
• third and fourth octets
• network portion
• host portion
• only the fourth octet

4. Given a host with the IP address 172.32.65.13 and a default subnet mask, to which network does the host belong?
• 172.32.65.0
• 172.32.65.32
• 172.32.0.0
• 172.32.32.0

5. Which default subnet mask provides the most host bits?
• 255.0.0.0
• 255.255.0.0
• 255.255.255.0
• 255.255.255.252

6. How many bits are available for Class B host IP addresses using a default subnet mask?
• 4
• 8
• 16
• 24

7. How many usable hosts are available given a Class C IP address with the default subnet mask?
• 254
• 255
• 256
• 510
• 511
• 512

8. Assuming a default mask, which portion of the IP address 175.124.35.4 represents the host?
• 175.124
• 35.4
• .4
• 124.35.4
• 175.124.35

9. Which of the following are private IP addresses? (Choose three.)
• 10.1.1.1
• 172.32.5.2
• 192.167.10.10
• 172.16.4.4
• 192.168.5.5
• 224.6.6.6

10. What destination IP address is used in a unicast packet?
• a specific host
• a group of hosts
• the default gateway
• the network broadcast address

11. What is the destination MAC address in a multicast Ethernet frame?
• the MAC address of the sending host
• the MAC address of the destination host
• an address that begins with 01-00-5E in hexadecimal
• a 48-bit hexadecimal address expressed as FF-FF-FF-FF-FF-FF

12. Yvonne is talking to her friend on the phone. What type of message is this?
• broadcast
• simulcast
• multicast
• unicast

13. What information must be included within a unicast message for it to be delivered on an Ethernet network?
• MAC and IP addresses for the default router
• IP address and subnet mask of the default gateway
• MAC and IP addresses that correspond to a destination group
MAC and IP addresses that correspond to a specific destination host

14. A PC obtains its IP address from a DHCP server. If the PC is taken off the network for repair, what happens to the IP address configuration?
• The configuration is permanent and nothing changes.
• The address lease is automatically renewed until the PC is returned.
• The address is returned to the pool for reuse when the lease expires.
• The configuration is held by the server to be reissued when the PC is returned.

15. Which type of server dynamically assigns an IP address to a host?
• ARP
• DHCP
• DNS
• RARP

16. Which three statements describe a DHCP Discover message? (Choose three.)
• The source MAC address is 48 ones (FF-FF-FF-FF-FF-FF).
• The destination IP address is 255.255.255.255.
• The message comes from a server offering an IP address.
• The message comes from a client seeking an IP address.
• All hosts receive the message, but only a DHCP server replies.
• Only the DHCP server receives the message.

17. Refer to the graphic. A host connects to a Linksys integrated router that is also a DHCP server and receives an IP address from it. Which address does the host need to access the ISP and the Internet?
• IP address of the destination host
• public gateway IP address of the ISP
• external IP address of the integrated router that connects to the ISP
• internal IP address of the integrated router that connects to the local network

18. Which statement is true concerning private IP addresses?
• ensures that two networks separated by the Internet use unique IP network numbers
• allows internal hosts to communicate with servers across the Internet
• solves the issue of a finite number of available public IP addresses
• allows for ISPs to be able to quickly determine network location

19. What is one of the purposes of NAT?
• filters network traffic based on IP address ranges
• prevents external users from detecting the IP addresses used on a network
• inspects traffic that might be harmful or used in an attack against the network
• translates IP addresses into easy-to-remember domain names

20. Which two statements describe packets that are sent through a Linksys integrated router using NAT? (Choose two.)
• Packets that are sent to any destination need to be translated.
• Packets that are sent to hosts on the same network need to be translated.
• Packets that are sent to a destination outside the local network need to be translated.
• Packets that are sent to a destination outside a local network do not need to be translated.
• Packets that are sent between hosts on the same local network do not need to be translated.

21. Refer to the graphic. NAT and DHCP are installed on the Linksys integrated router. Which IP address is most likely to be assigned to the local computer, Host1?
• 10.0.0.17
• 128.107.1.2
• 192.135.250.0
• 209.165.201.1

CCNA Discovery 1 - Module 6 Exam Answers V.4

2008-05-16T14:38:00.000-07:00

CCNA Discovery 1 - Module 6 Exam Answers V.4

1. A user types www.cisco.com into a web browser address textbox. What does www.cisco.com represent?
• the IP address of a web server
• a physical network address
• the closest router interface to the source
• the source IP address in the data transmission

2. What type of server would use IMAP?
• DNS
• DHCP
• e-mail
• FTP
• Telnet
• web

3. Which type of server would most likely be used first by a network client in a corporate environment?
• DNS
• DHCP
• e-mail
• FTP
• Telnet
• web

4. Which protocol is used by FTP to transfer files over the Internet?
• TCP
• SMTP
• UDP
• SNMP

5. Which protocols are TCP/IP application layer protocols? (Choose two.)
• UDP
• FTP
• IP
• SMTP
• TCP

6. Which of the following are layers of the TCP/IP model? (Choose three.)
• Application
• Physical
• Internet
• Network Access
• Presentation

7. You are creating a network-based video game. What influences your decision about which transport protocol to use for the application?
• UDP will not disrupt the game to retransmit dropped packets.
• TCP provides extra acknowledgements that will ensure smooth video delivery.
• Both TCP and UDP can be used simultaneously to ensure speed and guaranteed delivery.
• Both TCP and UDP may slow transmission and disrupt game operation, so no transport protocol should be used.

8. Whenever e-mail clients send letters, what device is used to translate the domain names into their associated IP addresses?
• Uniform Resource Locator
• Network redirector server
• SNMP server
• DNS server

9. Which application is most likely used to translate www.cisco.com to 198.133.219.25?
• DHCP
• DNS
• FTP
• HTTP
• POP
• SMTP

10. Refer to the graphic. Which protocol is used to access this website?
• IM
• FTP
• HTTP
• SNMP
• VoIP

11. Which port number is used by SMTP?
• 20
• 21
• 25
• 26
• 110

12. Which protocol is used by e-mail servers to communicate with each other?
• FTP
• HTTP
• TFTP
• SMTP
• POP
• SNMP

13. What client software enables logged in users to communicate with other logged in users in real time?
• blog
• e-mail
• web mail
• instant messaging

14. An Internet server is running both FTP and HTTP services. How does the server know which of these applications should handle an incoming segment?
• The packet header identifies it as an HTTP or FTP packet.
• The data in the segment is specially formatted for either HTTP or FTP.
• The segment destination port number identifies the application that should handle it.
• The source port number is associated with one of these well known server applications.

15. What term is used to describe how TCP/IP protocols are layered and interact to format, address, and transmit information across a network?
• protocol hierarchy
• protocol modeling
• protocol stack
• protocol layering

16. What three items are contained in an Ethernet frame? (Choose three.)
• source IP address
• source MAC address
• destination IP address
• destination MAC address
• error-checking information

17. What information is contained in an IP header?
• source and destination IP addresses
• source and destination MAC addresses
• only destination IP and MAC addresses
• both source and destination IP and MAC addresses

18. Cabling issues are associated with which OSI layer?
• 4
• 2
• 1
• 3

19. A device receives an Ethernet frame and recognizes the MAC address as its own. What does the device do to the message to get to the encapsulated data?
• removes the IP header
• removes the TCP header
• passes data to the application layer
• removes the Ethernet header and trailer

20. A client has decoded a frame and started the de-encapsulation process. In which order does the de-encapsulation process occur?
• 1) remove IP header
2) remove Ethernet header and trailer
3) remove TCP header
4) pass data to the application
• 1) add TCP header to data
2) add an IP header
3) add frame header and trailer
4) encode the frame into bits
• 1) remove Ethernet header and trailer
2) remove IP header
3) remove TCP header
4) pass data to the application
• 1) add TCP header to data
2) add Ethernet header and trailer
3) add an IP header
4) encode the frame into bits

21. What is an advantage of the use of layers in the OSI reference model?
• It breaks network communications into larger parts.
• It increases complexity.
• It prevents changes in one layer from affecting other layers.
• It requires the use of single-vendor equipment for hardware and software communications.

22. What is the correct order of the layers of the OSI reference model, starting at the lowest layer and working up the model?
• data link, physical, transport, network, presentation, session, application
• physical, data link, network, session, transport, presentation, application
• physical, data link, network, transport, presentation, session, application
• physical, data link, network, transport, session, presentation, application
• application, session, presentation, transport, data link, network, physical

CCNA Discovery 1 - Module 7 Exam Answers V.4

2008-05-16T04:34:00.000-07:00

CCNA Discovery 1 - Module 7 Exam Answers V.4

1. Why is IEEE 802.11 wireless technology able to transmit further distances than Bluetooth technology?
• transmits at much lower frequencies
• has higher power output
• transmits at much higher frequencies
• uses better encryption methods

2. What are three advantages of wireless over wired technology? (Choose three.)
• more secure
• longer range
• anytime, anywhere connectivity
• easy and inexpensive to install
• ease of using licensed air space
• ease of adding additional devices

3. What are two benefits of wireless networking over wired networking? (Choose two.)
• speed
• security
• mobility
• reduced installation time
• allows users to share more resources
• not susceptible to interference from other devices

4. A technician has been asked to provide wireless connectivity to the wired Ethernet network of a building. Which three factors affect the number of access points needed? (Choose three.)
• the size of the building
• the number of solid interior walls in the building
• the presence of microwave ovens in several offices
• the encryption method used on the wireless network
• the use of both Windows and Appletalk operating systems
• the use of shortwave or infrared on the AP

5. Why is security so important in wireless networks?
• Wireless networks are typically slower than wired networks.
• Televisions and other devices can interfere with wireless signals.
• Wireless networks broadcast data over a medium that allows easy access.
• Environmental factors such as thunderstorms can affect wireless networks.

6. What does the Wi-Fi logo indicate about a wireless device?
• IEEE has approved the device.
• The device is interoperable with all other wireless standards.
• The device is interoperable with other devices of the same standard that also display the Wi-Fi logo.
• The device is backwards compatible with all previous wireless standards.

7. Which statement is true concerning wireless bridges?
• connects two networks with a wireless link
• stationary device that connects to a wireless LAN
• allows wireless clients to connect to a wired network
• increases the strength of a wireless signal

8. Which WLAN component is commonly referred to as an STA?
• cell
• antenna
• access point
• wireless bridge
• wireless client

9. Which statement is true concerning an ad-hoc wireless network?
• created by connecting wireless clients in a peer-to-peer network
• created by connecting wireless clients to a single, centralized AP
• created by connecting multiple wireless basic service sets through a distribution system
• created by connecting wireless clients to a wired network using an ISR

10. Refer to the graphic. In the Wireless menu option of a Linksys integrated router, what does the Network Mode option Mixed mean?
• The router supports encryption and authentication.
• The router supports both wired and wireless connections.
• The router supports 802.11b, 802.11g, and 802.11n devices.
• The router supports connectivity through infrared and radio frequencies.

11. Refer to the graphic. In the Wireless menu of a Linksys integrated router, what configuration option allows the presence of the access point to be known to nearby clients?
• Network Mode
• Network Name (SSID)
• Radio Band
• Wide Channel
• Standard Channel
• SSID Broadcast

12. Which two statements about a service set identifier (SSID) are true? (Choose two.)
• tells a wireless device to which WLAN it belongs
• consists of a 32-character string and is not case sensitive
• responsible for determining the signal strength
• all wireless devices on the same WLAN must have the same SSID
• used to encrypt data sent across the wireless network

13. Which two statements characterize wireless network security? (Choose two.)
• Wireless networks offer the same security features as wired networks.
• Wardriving enhances security of wireless networks.
• With SSID broadcast disabled, an attacker must know the SSID to connect.
• Using the default IP address on an access point makes hacking easier.
• An attacker needs physical access to at least one network device to launch an attack.

14. What type of authentication does an access point use by default?
• Open
• PSK
• WEP
• EAP

15. Which statement is true about open authentication when it is enabled on an access point?
• requires no authentication
• uses a 64-bit encryption algorithm
• requires the use of an authentication server
• requires a mutually agreed upon password

16. What are two authentication methods that an access point could use? (Choose two.)
• WEP
• WPA
• EAP
• ASCII
• pre-shared keys

17. What is the difference between using open authentication and pre-shared keys?
• Open authentication requires a password. Pre-shared keys do not require a password.
• Open authentication is used with wireless networks. Pre-shared keys are used with wired networks.
• Pre-shared keys require an encrypted secret word. Open authentication does not require a secret word.
• Pre-shared keys require a MAC address programmed into the access point. Open authentication does not require this programming.

18. What term describes the encoding of wireless data to prevent intercepted data from being read by a hacker?
• address filtering
• authentication
• broadcasting
• encryption
• passphrase encoding

19. What access-point feature allows a network administrator to define what type of data can enter the wireless network?
• encryption
• hacking block
• traffic filtering
• MAC address filtering
• authentication

20. What are the two WEP key lengths? (Choose two.)
• 8 bit
• 16 bit
• 32 bit
• 64 bit
• 128 bit

21. Complete the following sentence: WEP is used to ______ , and EAP is used to _____ wireless networks.
• encrypt; authenticate users on
• filter traffic; select the operating frequency for
• identify the wireless network; compress data on
• create the smallest wireless network; limit the number of users on

CCNA Discovery 1 - Module 8 Exam Answers V.4

2008-05-16T04:32:00.000-07:00

CCNA Discovery 1 - Module 8 Exam Answers V.4

1. . Identify three techniques used in social engineering. (Choose three.)
• fishing
• vishing
• phishing
• spamming
• pretexting
• junk mailing

2. During a pretexting event, how is a target typically contacted?
• by e-mail
• by phone
• in person
• through another person

3. While surfing the Internet, a user notices a box claiming a prize has been won. The user opens the box unaware that a program is being installed. An intruder now accesses the computer and retrieves personal information. What type of attack occurred?
• worm
• virus
• Trojan horse
• denial of service

4. What is a major characteristic of a Worm?
• malicious software that copies itself into other executable programs
• tricks users into running the infected software
• a set of computer instructions that lies dormant until triggered by a specific event
• exploits vulnerabilities with the intent of propagating itself across a network

5. A flood of packets with invalid source-IP addresses requests a connection on the network. The server busily tries to respond, resulting in valid requests being ignored. What type of attack occurred?
• Trojan horse
• brute force
• ping of death
• SYN flooding

6. What type of advertising is typically annoying and associated with a specific website that is being visited?
• adware
• popups
• spyware
• tracking cookies

7. What is a widely distributed approach to marketing on the Internet that advertises to as many individual users as possible via IM or e-mail?
• brute force
• spam
• spyware
• tracking cookies

8. What part of the security policy states what applications and usages are permitted or denied?
• identification and authentication
• remote access
• acceptable use
• incident handling

9. Which statement is true regarding anti-virus software?
• Only e-mail programs need to be protected.
• Only hard drives can be protected.
• Only after a virus is known can an anti-virus update be created for it.
• Only computers with a direct Internet connection need it.

10. Which two statements are true concerning anti-spam software? (Choose two.)
• Anti-spam software can be loaded on either the end-user PC or the ISP server, but not both.
• When anti-spam software is loaded, legitimate e-mail may be classified as spam by mistake.
• Installing anti-spam software should be a low priority on the network.
• Even with anti-spam software installed, users should be careful when opening e-mail attachments.
• Virus warning e-mails that are not identified as spam via anti-spam software should be forwarded to other users immediately.

11. What term is used to describe a dedicated hardware device that provides firewall services?
• server-based
• integrated
• personal
• appliance-based

12. Which acronym refers to an area of the network that is accessible by both internal, or trusted, as well as external, or untrusted, host devices?
• SPI
• DMZ
• ISR
• ISP

13. Which statement is true about port forwarding within a Linksys integrated router?
• Only external traffic that is destined for specific internal ports is permitted. All other traffic is denied.
• Only external traffic that is destined for specific internal ports is denied. All other traffic is permitted.
• Only internal traffic that is destined for specific external ports is permitted. All other traffic is denied.
• Only internal traffic that is destined for specific external ports is denied. All other traffic is permitted.

14. To which part of the network does the wireless access point part of a Linksys integrated router connect?
• DMZ
• external
• internal
• a network other than the wired network

15. Refer to the graphic. What is the purpose of the Internet Filter option of Filter IDENT (Port 113. on the Linksys integrated router?
• to require a user ID and password to access the router
• to prevent outside intruders from attacking the router through the Internet
• to require a pre-programmed MAC address or IP address to access the router
• to disable tracking of internal IP addresses so they cannot be spoofed by outside devices

16. What statement is true about security configuration on a Linksys integrated router?
• A DMZ is not supported.
• The router is an example of a server-based firewall.
• The router is an example of an application-based firewall.
• Internet access can be denied for specific days and times.

17. What environment would be best suited for a two-firewall network design?
• a large corporate environment
• a home environment with 10 or fewer hosts
• a home environment that needs VPN access
• a smaller, less congested business environment

18. What is one function that is provided by a vulnerability analysis tool?
• It provides various views of possible attack paths.
• It identifies missing security updates on a computer.
• It identifies wireless weak points such as rogue access points.
• It identifies all network devices on the network that do not have a firewall installed.
• It identifies MAC and IP addresses that have not been authenticated on the network.

19. Many best practices exist for wired and wireless network security. The list below has one item that is not a best practice. Identify the recommendation that is not a best practice for wired and wireless security.
• Periodically update anti-virus software.
• Be aware of normal network traffic patterns.
• Periodically update the host operating system.
• Activate the firewall on a Linksys integrated router.
• Configure login permissions on the integrated router.
• Disable the wireless network when a vulnerability analysis is being performed.

20. What best practice relates to wireless access point security?
• activation of a popup stopper
• a change of the default IP address
• an update in the antivirus software definitions
• physically securing the cable between the access point and client

21. Refer to the graphic. In the Linksys Security menu, what does the SPI Firewall Protection option Enabled provide?
• It prevents packets based on the application that makes the request.
• It allows packets based on approved internal MAC or IP addresses.
• It requires that packets coming into the router be responses to internal host requests.
• It translates an internal address or group of addresses into an outside, public address.

CCNA Discovery 1 - Module 9 Exam Answers V.4

2008-05-16T04:24:00.000-07:00

CCNA Discovery 1 - Module 9 Exam Answers V.4

1. What should a network administrator do first after receiving a call from a user who cannot access the company web server?
• Reboot the web server.
• Replace the NIC of the computer.
• Ask the user to log off and log on again.
• Ask the user what URL has been typed and what error message displays.

2. A customer called the cable company to report that the Internet connection is unstable. After trying several configuration changes, the technician decided to send the customer a new cable modem to try. What troubleshooting technique does this represent?
• top-down
• bottom-up
• substitution
• trial-and-error
• divide-and-conquer

3. Only one workstation on a particular network cannot reach the Internet. What is the first troubleshooting step if the divide-and-conquer method is being used?
• Check the NIC, and then check the cabling.
• Check the workstation TCP/IP configuration.
• Test all cables, and then test layer by layer up the OSI model.
• Attempt to Telnet, and then test layer by layer down the OSI model.

4. Which two troubleshooting techniques are suitable for both home networks and large corporate networks? (Choose two.)
• having a backup ISR
• running network monitoring applications
• documenting the troubleshooting process
• keeping a record of system upgrades and software versions
• keeping spare switches, routers, and other equipment available

5. Identify two physical-layer network problems. (Choose two.)
• hardware failure
• software configuration
• devices not able to ping
• loose cable connections
• device driver configuration

6. Which ipconfig command requests IP configuration from a DHCP server?
• ipconfig
• ipconfig /all
• ipconfig /renew
• ipconfig /release

7. What command is used to determine the location of delay for a packet traversing the Internet?
• ipconfig
• netstat
• nslookup
• ping
• tracert

8. What command is used to determine if a DNS server is providing name resolution?
• ipconfig
• netstat
• nslookup
• tracert

9. Which troubleshooting method begins by examining cable connections and wiring issues?
• top-down
• bottom-up
• substitution
• divide-and-conquer

10. A technician suspects that a Linksys integrated router is the source of a network problem. While troubleshooting, the technician notices a blinking green activity LED on some of the ports. What does this indicate?
• Self-diagnostics have not completed.
• The power supply is the source of the problem.
• The ports are operational and are receiving traffic.
• The ports are operational, but no traffic is flowing.
• There are no cables plugged into those ISR ports.
• The ports have cables plugged in, but they are not functional.

11. A PC is plugged into a switch and is unable to connect to the network. The UTP cable is suspected. What could be the problem?
• A straight-through cable is being used
• The connectors at both ends of the cable are RJ-45.
• The RJ-45 connectors are crimped onto the cable jacket.
• A crossover cable is being used.

12. Refer to the graphic. What configuration is incorrect in the network shown?
• The host IP address is incorrect.
• The host subnet mask is incorrect.
• The host default gateway is incorrect.
• The wired connection is the wrong type of cable.
• The Linksys integrated router does not support wireless.

13. Which three settings must match on the client and access point for a wireless connection to occur? (Choose three.)
• SSID
• authentication
• MD5 checksum
• antennae type
• encryption key
• MAC address filters

14. A technician is troubleshooting a security breach on a new wireless access point. Which three configuration settings make it easy for hackers to gain access? (Choose three.)
• configuring NAT
• broadcasting the SSID
• using open authentication
• enabling MAC address filters
• using the default internal IP address
• using DHCP to provide IP addresses

15. Refer to the graphic. The wireless host cannot access the Internet, but the wired host can. What is the problem?
• The host WEP key is incorrect.
• The host IP address is incorrect.
• The host subnet mask is incorrect.
• The host default gateway is incorrect.
• The integrated router internal IP address is incorrect.
• The integrated router Internet IP address is incorrect.

16. Refer to the graphic. What configuration is incorrect in the network shown?
• The host IP address is incorrect.
• The host subnet mask is incorrect.
• The host default gateway is incorrect.
• The wired connection is the wrong type of cable.
• The Linksys integrated router does not support wireless.

17. When acting as a DHCP server, what three types of information can an ISR provide to a client? (Choose three.)
• physical address
• MAC address
• default gateway
• static IP address
• dynamic IP address
• DNS server address

18. What two items could be checked to verify connectivity between the router and the ISP? (Choose two.)
• router status page
• wireless card settings
• router operating system version
• local host operating system version
• connectivity status as indicated by LEDs

19. A technician is unsuccessful in establishing a console session between a PC and a Linksys integrated router. Both devices have power, and a cable is connected between them. Which two troubleshooting steps could help to diagnose this problem? (Choose two.)
• Ensure the correct cable is used.
• Ensure the SSID is the same on both devices.
• Ensure both devices have the same IP address.
• Ensure both devices have different subnet masks.
• Ensure the encryption type on both devices match.
• Ensure the link status LED on the integrated router is lit.

20. Network baselines should be performed in which two situations? (Choose two.)
• after the network is installed and running optimally
• after a virus outbreak is discovered on the network
• after major changes are implemented on the network
• after several computers are added to the network
• at the end of the work week

21. Typically, help desk personnel assist end users in which two tasks? (Choose two.)
• identifying when the problem occurred
• determining if other users are currently logged into the computer
• updating network diagrams and documentation
• implementing the solution to the problem
• running a network baseline test
• determining the cost of fixing the problem

22. How does remote-access software help in the troubleshooting process?
• Remote access uses a live chat feature.
• Users have to be present so that they can view LEDs and change cables if necessary.
• Diagnostics can be run without a technician being present at the site.
• FAQs can be consulted more easily.

23. Which two items should be added to the documentation following a troubleshooting event? (Choose two.)
• final resolution
• repetitive measures
• number of people involved in the problem
• accurate current network infrastructure diagrams
• results of successful and unsuccessful troubleshooting steps

CCNA Discovery 1 - FINAL Exam Answers

2008-05-16T04:22:00.000-07:00

CCNA Discovery 1 - FINAL Exam Answers

1. Which three statements are true about local and network applications? (Choose three.)
• A local application is loaded in a local computer and can be accessed by a remote computer on the network.
• A network application is loaded in a local computer and accessed from a remote computer.
• A local application is loaded in a local computer and accessed only by the local computer.
• A network application is loaded in a local computer and accessed only by the local computer.
• An example of a local application is e-mail.
• An example of a network application is instant messaging.

2. A wireless DHCP client cannot connect to the Internet through a Linksys integrated router. When you type ipconfig on the host, no IP address, subnet mask, or default gateway shows. What are two of the first things you will check? (Choose two.)
• SSID
• if the wireless client is configured for DHCP
• the cable between client and integrated router
• the firewall configuration on the integrated router
• if the correct default gateway is configured on the client
• if the correct default gateway is configured on the integrated router

3. Refer to the graphic. Assume that the command output is from a wireless DHCP client that is connected to a Linksys integrated router. What can be deduced from the output?
• The wireless connection is good.
• The WEP key or SSID needs to be checked.
• The DHCP configuration on the router needs to be checked.
• The wireless NIC driver or the NIC itself needs to be reinstalled.

4. What measurement is commonly used to describe communication speed when transferring data?
• bps
• cps
• Hz
• MB

5. What is an accurate description of network devices in the distribution layer?
• They are designed to interconnect individual hosts.
• They are designed to interconnect multiple companies.
• They are designed to interconnect local network segments.
• They are designed to switch data packets as fast as possible.

6. When acting as a DHCP server, an integrated router can provide what three types of information to a client? (Choose three.)
• physical address
• MAC address
• default gateway
• static IP address
• dynamic IP address
• DNS server address

7. Where do ISPs get the public addresses that they assign to end users?
• ISPs create the addresses themselves.
• ISPs are assigned addresses through the RFC.
• ISPs obtain their addresses automatically.
• ISPs obtain address blocks from registry organizations.

8. Refer to the graphic. What is the effect of setting the security mode to WEP on the Linksys integrated router?
• It identifies the wireless LAN.
• It allows the access point to inform clients of its presence.
• It translates IP addresses into easy-to-remember domain names.
• It encrypts data between the wireless client and the access point.
• It ensures that only authorized users are allowed access to the WLAN.
• It translates an internal address or group of addresses into an outside, public address.

9. When are leased lines typically used?
• when low bandwidth is required
• for home and small business connectivity
• when a dedicated digital data line is necessary
• as a less expensive option to cable and DSL modem service

10. Which wireless protocol is used for encryption?
• EAP
• Open
• PSK
• WEP

11. The area covered by a single AP is known as what?
• ad-hoc network
• basic service set
• independent basic service set
• extended service set
• distribution system

12. Which installation option should be chosen when the current operating system is too damaged to work properly?
• upgrade
• multi-boot
• clean install
• virtualization

13 . What layer is the first point of entry for a host into the network?
• core layer
• access layer
• network layer
• distribution layer

14. What two commands can be used to form a new binding if client information does not agree with the DHCP client table? (Choose two.)
• ipconfig /release
• ipconfig /all
• ipconfig /flushdns
• ipconfig /renew
• ipconfig

15. What are two advantages of purchasing a custom-built computer? (Choose two.)
• usually a lower cost
• no waiting period for assembly
• user can specify higher performance components
• supports higher-end graphics and gaming applications
• fewer components to replace

16. What information within a data packet does a router use, by default, to make forwarding decisions?
• the destination MAC address
• the destination IP address
• the destination host name
• the destination service requested

17. What is a service pack?
• an access policy
• an agreement between a company and a vendor
• a piece of code created to fix one specific problem
• a collection of patches and updates released by a vendor
• a small piece of software designed specifically for security issues

18. What is an ISP?
• It is a standards body that develops cabling and wiring standards for networking.
• It is a protocol that establishes how computers within a local network communicate.
• It is an organization that allows individuals and businesses to connect to the Internet.
• It is a networking device that combines the functionality of several different networking devices in one.

19. Which two statements correctly describe Media Access Control (MAC) addresses? (Choose two.)
• MAC addresses are used to identify a specific NIC.
• MAC addresses are physical addresses.
• MAC addresses contain a network number and unique host identification.
• MAC addresses are always assigned to network devices by a network administrator.
• MAC addresses can be dynamically assigned.

20. What is the name for the contract between a customer and an ISP that specifies requirements for uptime and service response time?
• DSL
• IAB
• NAP
• SLA

21. What are two ways that a user can interact with an operating system shell? (Choose two.)
• CLI
• OS
• GUI
• NIC
• kernel

22. Select the connection that would require a straight-through cable.
• a switch to a hub
• a router to a switch
• a switch to a switch
• a router to a router

23. Choose the option that shows the correct sequence of steps in the encapsulation of TCP/IP data that is passed from a source to a destination host?
A. converts data to bits for transmission
B. packages the data for end to end transport
C. adds the data-link header and trailer
D. adds the network IP address to the header of the frame
• A,B,C,D
• A,C,D,B
• B,D,C,A
• B,C,D,A
• D,C,B,A

24. What is specified by the network number in an IP address?
• the network to which the host belongs
• the physical identity of the computer on the network
• the node of the subnetwork which is being addressed
• the broadcast identity of subnetwork

25. Refer to the graphic. What is the purpose of assigning a Network Name of Academy?
• It identifies the wireless LAN.
• It translates IP addresses into easy-to-remember domain names.
• It encrypts data between the wireless client and the access point.
• It allows access to the AP configuration GUI by name rather than address.
• It translates an internal address or group of addresses into an outside, public address.

26. Which of the following statements best describes DNS?
• DNS servers are used to map an IP address to a physical address.
• DNS servers are used to map a name to an IP address.
• DNS servers are used to configure logical address information for host computers.
• DNS servers are used to translate from private addresses to public addresses.

27. Which of the following are the address ranges of the private IP addresses? (Choose three.)
• 10.0.0.0 to 10.255.255.255
• 200.100.50.0 to 200.100.25.255
• 150.150.0.0 to 150.150.255.255
• 172.16.0.0 to 172.31.255.255
• 192.168.0.0 to 192.168.255.255
• 127.16.0.0 to 127.31.255.255

28. Which protocol is used to transfer files among network devices and perform file-management functions?
• DNS
• FTP
• HTML
• HTTP

29. Select three statements that correctly describe how DHCP services may be provided. (Choose three.)
• An integrated router provides IP configurations for most ISPs.
• An integrated router can act as both DHCP server and DHCP client.
• A home PC using a static IP address obtained that address from a DHCP server.
• Most home network integrated routers receive an IP configuration directly from their ISP.
• A variety of devices can act as DHCP servers, as long as they run DHCP service software.
• A home PC is required by standards to obtain an IP address and default gateway from a DHCP server (usually the ISP).

30. Refer to the graphic. Based on the information that is shown, what statement is true?
• This configuration would be commonly found in an ad hoc wireless network.
• Any wireless client that is attached to this access point would have the same IP address and SSID.
• All wireless devices that are connected to this access point must have an assigned SSID of Academy.
• In addition to accepting wireless client requests, this access point must connect to the wired network.

31. Identify two causes of physical layer network problems. (Choose two.)
• logical addressing issues
• improperly terminated cables
• cables plugged into wrong ports
• incorrect MAC address assigned
• packets received out of sequence
• incorrect subnet mask on an interface

32. Which part of the electromagnetic spectrum is commonly used to exchange data between a PDA and a computer?
• FM
• radar
• infrared
• ultraviolet

33. Which of the following are transport layer protocols of the TCP/IP model? (Choose two.)
• FTP
• UDP
• SMTP
• TFTP
• TCP

34. For the second time in a week, workstations on a LAN are not able to log into the server. The technician fixed the problem the first time, but cannot remember the steps taken to solve it. What aspect of the troubleshooting process has the technician neglected?
• identifying the problem
• asking end-users questions
• documenting the troubleshooting process
• using structured techniques to solve a problem

35. What action will a router take when it receives a frame with a broadcast MAC address?
• It will not forward the frame to another network.
• It forwards the frame back to the sending host with its IP address as a response.
• It forwards the frame out of all interfaces except the interface where the frame was received.
• It forwards the frame back out the receiving interface to insure all hosts on the local network receive it.

36. A network host is accessing a web server. What two protocols are most likely being used as the TCP/IP model application layer protocol and the internetwork layer protocol? (Choose two.)
• IP
• FTP
• TCP
• DHCP
• HTTP

37. Which statement is true concerning stateful packet inspection?
• Access is permitted based on IP addresses of the source and destination devices.
• Access is permitted based on the MAC addresses of the source and destination devices.
• Access is permitted only if the type of application that is attempting to reach the internal host is allowed.
• Access is permitted only if it is a legitimate response to a request from an internal host.

38. What does the term "attenuation" mean in data communication?
• loss of signal strength as distance increases
• time for a signal to reach its destination
• leakage of signals from one cable pair to another
• strengthening of a signal by a networking device

39. What is the default subnet mask for a class B address?
• 255.0.0.0
• 255.255.0.0
• 255.255.255.0
• 255.255.255.255

40. Refer to the graphic. Based on the configuration information that is shown, which three types of 802.11 networks are allowed access to the WLAN? (Choose three.)
• 802.11a
• 802.11b
• 802.11e
• 802.11g
• 802.11n
• 802.11x

41. Within a local network, which two items must be unique on a computer for it to successfully connect to the network? (Choose two.)
• IP address
• subnet mask
• computer name
• default gateway address
• operating system version

42. When considering the purchase of a new operating system, what is meant by "Total Cost of Ownership?"
• applications and support costs
• hardware and support costs
• hardware and software costs
• hardware, software, and support costs
• hardware, operating system, and applications costs

43. A computer joins the network and announces itself to all hosts on the LAN. What type of message does the computer send out?
• broadcast
• simulcast
• multicast
• unicast

44. Refer to the graphic. What feature can be installed on the Linksys integrated router to convert private IP addresses to Internet-routable addresses?
• authentication
• DHCP
• encryption
• firewall
• NAT
• WEP

45. When terminating UTP cabling, why is it important to untwist only a small amount of each wire pair?
• minimizes crosstalk
• makes installation faster
• ensures wires are in correct order
• makes it easier to fit wires into connector

46. A host sent a message that all other hosts on the local network received and processed. What type of domain are all these hosts a part of?
• local domain
• multicast domain
• collision domain
• broadcast domain

47. Your school network blocks all websites related to online gaming. What type of security policy is being applied?
• identification and authentication
• remote access
• acceptable use
• incident handling

48. Refer to the graphic. Assume that the exhibited output is from a host that is connected to a Linksys integrated router. What is one of the first things you should check?
• IP address on the host
• IP address on the router
• subnet mask on the host
• default gateway on the host
• link status LED on the front of the router

49. The transmit pins are disconnected and only the receive pins are used.
• The transmit pins on one device are connected to the transmit pins on the other device.
• The receive pins on one device are connected to the receive pins on the other device.
• The transmit pins on one device are connected to the receive pins on the other device.

50. What are two examples of storage peripheral devices? (Choose two.)
• printer
• flash drive
• headphones
• external DVD
• barcode reader

51. What are the two possible values for a digital bit? (Choose two.)
• 0
• 1
• A
• F
• #
• 9

52. What type of computer would most likely use a docking station?
• laptop
• server
• desktop
• mainframe
• workstation

CCNA4 Exploration FINAL Exam (Score 87.5)

2008-05-16T04:10:00.000-07:00

CCNA4 Exploration FINAL Exam (Score 87.5)

1. A technician has been asked to run Cisco SDM one-step lockdown on the router of a customer. What will be the result of this process?

Traffic is only forwarded from SDM-trusted Cisco routers.
Security testing is performed and the results are saved as a text file stored in NVRAM.
**The router is tested for potential security problems and any necessary changes are made.
All traffic entering the router is quarantined and checked for viruses before being forwarded.

2. Refer to the exhibit. A network administrator is trying to configure a router to use SDM but it is not functioning correctly. What could be the problem?

The username and password are not configured correctly.
The authentication method is not configured correctly.
The HTTP timeout policy is not configured correctly.
**The vtys are not configured correctly.

3. Refer to the exhibit. How is the TCP/IP configuration information specified by the default-router and dns-server commands made available?

The TCP/IP information is forwarded to a 10.0.1.3 to be supplied to DHCP clients.
**The TCP/IP information is used by DHCP clients that are configured to request a configuration from R1.
The TCP/IP information is supplied to any DHCP client on the network connected to the FastEthernet 0/0 interface of R1.
The TCP/IP information is applied to each packet that enters R1 through the FastEthernet 0/0 interface that are hosts on the 10.0.1.0 /24 network except packets from addresses 10.0.1.2, 10.0.1.16, and 10.0.1.254.

4. What is a major characteristic of a worm?

malicious software that copies itself into other executable programs
tricks users into running the infected software
a set of computer instructions that lies dormant until triggered by a specific event
**exploits vulnerabilities with the intent of propagating itself across a network

5. Refer to the exhibit. What can be concluded from the exhibited output of the debug ip nat command?

The 10.1.1.225 host is exchanging packets with the 192.168.0.10 host.

The native 10.1.200.254 address is being translated to 192.168.0.10.

**The 192.168.0.0/24 network is the inside network.

Port address translation is in effect.

6. A technician is talking to a colleague at a rival company and comparing DSL transfer rates between the two companies. Both companies are in the same city, use the same service provider, and have the same rate/service plan. What is the explanation for why Company A reports higher download speeds than Company B?

Company B has a higher volume of POTS voice traffic than Company A.

Company B shares the conection to the DSLAM with more clients than Company A.

Company A only uses microfilters on branch locations.

**Company A is closer to the service provider.

7. Refer to the exhibit. Which statement correctly describes how Router1 processes an FTP request entering interface s0/0/0, destined for an FTP server at IP address 192.168.1.5?

It matches the incoming packet to the access-list 201 permit any any statement and allows the packet into the router.
**It reaches the end of ACL 101 without matching a condition and drops the packet because there is no access-list 101 permit any any statement.

It matches the incoming packet to the access-list 101 permit ip any 192.168.1.0 0.0.0.255 statement, ignores the remaining statements in ACL 101, and allows the packet into the router.

It matches the incoming packet to the access-list 201 deny icmp 192.168.1.0 0.0.0.255 any statement, continues comparing the packet to the remaining statements in ACL 201 to ensure that no subsequent statements allow FTP, and then drops the packet.

8. Refer to the exhibit. Which two conclusions can be drawn from the output shown? (Choose two.)

This network is experiencing congestion.

**The Frame Relay connection is in the process of negotiation.
Data is not flowing in this network.

**The network is discarding eligible packets.

The DLCI is globally significant.

9. A system administrator must provide Internet connectivity for ten hosts in a small remote office. The ISP has assigned two public IP addresses to this remote office. How can the system administrator configure the router to provide Internet access to all ten users at the same time?

Configure DHCP and static NAT.

Configure dynamic NAT for ten users.

Configure static NAT for all ten users.

**Configure dynamic NAT with overload.

10. Refer to the exhibit. Company ABC expanded its business and recently opened a new branch office in another country. IPv6 addresses have been used for the company network. The data servers Server1 and Server2 run applications which require end-to-end functionality, with unmodified packets that are forwarded from the source to the destination. The edge routers R1 and R2 support dual stack configuration. What solution should be deployed at the edge of the company network in order to successfully interconnect both offices?

a new WAN service supporting only IPv6

NAT overload to map inside IPv6 addresses to outside IPv4 address

**a manually configured IPv6 tunnel between the edge routers R1 and R2

static NAT to map inside IPv6 addresses of the servers to an outside IPv4 address and dynamic NAT for the rest of the inside IPv6 addresses

11. Refer to the exhibit. You are a network administrator who has been tasked with completing the Frame Relay topology that interconnects two remote sites. How should the point-to-point subinterfaces be configured on HQ to complete the topology?

HQ(config-subif)#frame-relay interface-dlci 103 on Serial 0/0/0.1
HQ(config-subif)#frame-relay interface-dlci 203 on Serial 0/0/0.2
**HQ(config-subif)#frame-relay interface-dlci 301 on Serial 0/0/0.1
HQ(config-subif)# frame-relay interface-dlci 302 on Serial 0/0/0.2

HQ(config-subif)#frame-relay map ip 172.16.1.1 103 broadcast on Serial 0/0/0.1
HQ(config-subif)#frame-relay map ip 172.16.2.2 203 broadcast on Serial 0/0/0.2
HQ(config-subif)#frame-relay map ip 172.16.1.1 301 broadcast on Serial 0/0/0.1
HQ(config-subif)#frame-relay map ip 172.16.2.2 302 broadcast on Serial 0/0/0.2

12. An established company has recently transitioned from outsourced LAN support to a completely in-house staff. The outsourcing company is no longer in business, so no records are available. There are many user complaints about application speed and availability. What two considerations apply to this situation? (Choose two.)

A network utilization baseline should quickly reveal application availability.

A period of 24 to 48 hours should provide a sufficient baseline to track normal network activity.

It is easier to start with monitoring all available data inputs on application servers, and then fine-tune to fewer variables along the way.

The initial baseline results have little relevance to current values after the network has been modified or grown in usage.

**When it is practical, network administrators should attempt to automate the collection of performance data and stay away from manual collection.

**Creating a network baseline data helps determine device thresholds for alerting.

13. Which combination of Layer 2 protocol and authentication should be used to establish a link without sending authentication information in plain text between a Cisco and a non-Cisco router?

PPP with PAP

**PPP with CHAP

HDLC with PAP

HDLC with CHAP

14. An administrator is unable to receive e-mail. While troubleshooting the problem, the administrator is able to ping the local mail server IP address successfully from a remote network and can successfully resolve the mail server name to an IP address via the use of the nslookup command. At what OSI layer is the problem most likely to be found?

physical layer

data link layer

network layer

**application layer

15. When configuring a Frame Relay connection, what are two instances when a static Frame Relay map should be used? (Choose two.)

when the remote router is a non-Cisco router

**when the remote router does not support Inverse ARP

when the local router is using IOS Release 11.1 or earlier

**when broadcast traffic and multicast traffic over the PVC must be controlled

when globally significant rather than locally significant DLCIs are being used

16. Which three statements are true about creating and applying access lists? (Choose three.)

Access list entries should filter in the order from general to specific.

**One access list per port per protocol per direction is permitted.

Standard ACLs should be applied closest to the source while extended ACLs should be applied closest to the destination.

**There is an implicit deny at the end of all access lists.

**Statements are processed sequentially from top to bottom until a match is found.

The inbound keyword refers to traffic entering the network from the router interface where the ACL is applied.

17. Which technology would provide the highest bandwidth connections between company sites at the lowest cost?

**broadband Internet site-to-site VPN connections

satellite based network connections

dedicated point-to-point circuits

Frame Relay PVCs

18. Refer to the exhibit. This serial interface is not functioning correctly. Based on the output shown, what is the most likely cause?

improper LMI type

interface reset

**PPP negotiation failure

unplugged cable

19. What three statements describe the roles of devices in a WAN? (Choose three.)

**A CSU/DSU terminates a digital local loop.

A modem terminates a digital local loop.

A CSU/DSU terminates an analog local loop.

**A modem terminates an analog local loop.

**A router is commonly considered a DTE device.

A router is commonly considered a DCE device.

20. A network administrator is instructing a technician on best practices for applying ACLs. Which suggestion should the administrator provide?

Named ACLs are less efficient than numbered ACLs.

Standard ACLs should be applied closest to the core layer.

ACLs applied to outbound interfaces are the most efficient.

**Extended ACLs should be applied closest to the source that is specified by the ACL.

21. Refer to the exhibit. Branch A has a Cisco router. Branch B has a non-Cisco router set for IETF encapsulation. After the commands shown are entered, R2 and R3 fail to establish the PVC. The R2 LMI is Cisco, and the R3 LMI is ANSI. The LMI is successfully established at both locations. Why is the PVC failing?

The PVC to R3 must be point-to-point.

LMI types must match on each end of a PVC.

**The ietf parameter is missing from the frame-relay map ip 10.10.10.3 203 command.

The PVCs at R2 use different encapsulation types. A single port can only support one encapsulation type.

22. Which statement is true regarding wildcard masks?

The wildcard mask and subnet mask perform the same function.

The wildcard mask is always the inverse of the subnet mask.

**A "0" in the wildcard mask identifies IP address bits that must be checked.

A "1" in the wildcard mask identifies a network or subnet bit.

23. Refer to the exhibit. What is placed in the address field in the header of a frame that will travel from the DC office of ABC Company to the Orlando office?

MAC address of the Orlando router

MAC address of the DC router

192.168.1.25

192.168.1.26

DLCI 100

**DLCI 200

24 .A company is looking for a WAN solution to connect its headquarters site with four remote sites. What advantage would dedicated leased lines provide to the customer compared to a shared Frame Relay solution?

lower cost

lower latency and jitter

**variable bandwidth capacity

fewer physical router interfaces

25. Refer to the exhibit. RIPv2 has been configured on all routers in the network. Routers R1 and R3 do not receive RIP routing updates. On the basis of the provided configuration, what should be enabled on router R2 to remedy the problem?

proxy ARP

CDP updates

SNMP services

**RIP authentication

26. What are the symptoms when the s0/0/0 interface on a router is attached to an operational CSU/DSU that is generating a clock signal, but the far end router on the point-to-point link has not been activated?

show controllers indicates cable type DCE V.35. show interfaces s0/0/0 indicates serial down, line protocol down.

show controllers indicates cable type DCE V.35. show interfaces s0/0/0 indicates serial up, line protocol down.

**show controllers indicates cable type DTE V.35. show interfaces s0/0/0 indicates serial up, line protocol down.

show controllers indicates cable type DTE V.35. show interfaces s0/0/0 indicates serial down, line protocol down.

27. Which statement about a VPN is true?

VPN link establishment and maintenance is provided by LCP.

DLCI addresses are used to identify each end of the VPN tunnel.

**VPNs use virtual Layer 3 connections that are routed through the Internet.

Only IP packets can be encapsulated by a VPN for tunneling through the Internet.

28. Refer to the exhibit. Partial results of the show access-lists and show ip interface FastEthernet 0/1 commands for router R3 are shown. There are no other ACLs in effect. Host A is unable to telnet to host B. Which action will correct the problem but still restrict other traffic between the two networks?

Apply the ACL in the inbound direction.

Apply the ACL on the FastEthernet 0/0 interface.

**Reverse the order of the TCP protocol statements in the ACL.

Modify the second entry in the list to permit tcp host 192.168.10.10 any eq telnet .

29. Refer to the exhibit. What happens if the network administrator issues the commands shown when an ACL called Managers already exists on the router?

The commands overwrite the existing Managers ACL.

**The commands are added at the end of the existing Managers ACL.

The network administrator receives an error stating that the ACL already exists.

The commands will create a duplicate Managers ACL containing only the new commands being entered.

30. Which three statements accurately describe a security policy? (Choose three.)

**It creates a basis for legal action if necessary.

**It defines a process for managing security violations.

**It defines acceptable and unacceptable use of network resources.

The remote access policy is a component of the security policy that governs acceptable use of e-mail systems.

It is kept private from users to prevent the possibility of circumventing security measures.

It provides step-by-step procedures to harden routers and other network devices.

31. Refer to the exhibit. The link between the CTRL and BR_1 routers is configured as shown in the exhibit. Why are the routers unable to establish a PPP session?

The clock rate must be 56000.

**The usernames are misconfigured.

The IP addresses are on different subnets.

The clock rate is configured on the wrong end of the link.

The CHAP passwords must be different on the two routers.

Interface serial 0/0/0 on CTRL must connect to interface serial 0/0/1 on BR_1.

32. What effect would the Router1(config-ext-nacl)# permit tcp 172.16.4.0 0.0.0.255 any eq www command have when implemented inbound on the f0/0 interface?

All TCP traffic is permitted, and all other traffic is denied.

The command is rejected by the router because it is incomplete.

All traffic from 172.16.4.0/24 is permitted anywhere on any port.

**Traffic originating from 172.16.4.0/24 is permitted to all TCP port 80 destinations.

33. What can a network administrator do to recover from a lost router password?

use the copy tftp: flash: command

boot the router to bootROM mode and enter the b command to load the IOS manually

telnet from another router and issue the show running-config command to view the password

**boot the router to ROM monitor mode and configure the router to ignore the startup configuration when it initializes

34. A router in a Frame Relay network needs to forward a message received from a host. What two methods does the router use to identify the correct VC to forward the message? (Choose two.)

The router forwards the frame to all ports in the network and learns the address from the reply frame.

The destination host IP address is embedded in the DLCI.

The router searches Inverse ARP tables for maps of DLCIs to IP addresses.

**A table of static mappings can be searched.

The router broadcasts a request for the required IP address.

35. Refer to the exhibit. From the output of the show interface commands, at which OSI layer is a fault indicated?

application

transport

network

**data link

physical

36. Refer to the exhibit. The network administrator creates a standard access control list to prohibit traffic from the 192.168.1.0/24 network from reaching the 192.168.2.0/24 network while still permitting Internet access for all networks. On which router interface and in which direction should it be applied?

interface fa0/0/0, inbound

interface fa0/0/0, outbound

interface fa0/0/1, inbound

**interface fa0/0/1, outbound

37. Refer to the exhibit. The SSH connections between the remote user and the server are failing. The correct configuration of NAT has been verified. What is the most likely cause of the problem?

SSH is unable to pass through NAT.

**There are incorrect access control list entries.

The access list has the incorrect port number for SSH.

The ip helper command is required on S0/0/0 to allow inbound connections.

38. Refer to the exhibit. A technician issues the show interface s0/0/0 command on R1 while troubleshooting a network problem. What two conclusions can be determined by from the output shown? (Choose two.)

**The bandwidth has been set to the value of a T1 line.

Encapsulation should of this inteface be changed to PPP.

**There is no failure indicated in an OSI Layer 1 or Layer 2.

The physical connection between the two routers has failed.

The IP address of S0/0 is invalid, given the subnet mask being used.

39. Refer to the exhibit. A packet is being sent from Host A to Host B through the VPN tunnel between R1 and R3. When the packet first arrives at R3, what are the source and destination IP addresses of the packet?

Source 192.168.1.2 - Destination 192.168.4.2

Source 192.168.3.1 - Destination 192.168.3.2

**Source 192.168.2.1 - Destination 192.168.3.2

Source 192.168.3.1 - Destination 192.168.4.2

40. An administrator is configuring a dual stack router with IPv6 and IPv4 using RIPng. The administrator receives an error message when trying to enter the IPv4 routes into RIPng. What is the cause of the problem?

RIPng is incompatible with dual-stack technology.

All interfaces have been configured with the incorrect IPv4 addresses.

**RIPv1 or RIPv2 needs to be configured in addition to RIPng to successfully use IPv4.

When IPv4 and IPv6 are configured on the same interface, all IPv4 addresses are shut down in favor of the newer technology.

41. Which wireless solution can provide mobile users with non line-of-sight broadband Internet access at speeds comparable to DSL or cable?

Wi-Fi

WiMAX

**satellite

Metro Ethernet

42. A network administrator added two switches and a new VLAN over the past weekend. How can the administrator determine if the additions and changes improved performance and availability on the company intranet?

**Perform a baseline test and compare the current values to values that were obtained in previous weeks.

Interview departmental secretaries and determine if they think load time for web pages is improved.

Compare the hit counts on the company web server for the current week to the values that were recorded from previous weeks.

Performance on the intranet can be determined by monitoring load times of company web pages from remote sites.

43. Refer to the exhibit. The network administrator is adding R1 to an existing network. As a part of the corporate IT procedures, the administrator attempts to back up the router Cisco IOS software of R1 and receives the output shown. The network administrator then attempts unsuccessfully to ping the TFTP server from the console session. What should be done next to isolate this problem?

From R2, validate that interface Fa0/0 is operational.

From the TFTP server, verify that the software on the TFTP server is operational.

From the TFTP server, confirm there is enough room on the TFTP server for the Cisco IOS software.

**From the console session, make sure that R1 has a route to the network where the TFTP server resides.

44. What functionality do access control lists provide when implementing dynamic NAT on a Cisco router?

**defines which addresses can be translated

defines which addresses are assigned to a NAT pool

defines which addresses are allowed out of the router

defines which addresses can be accessed from the inside network

45. A network administrator is working with an applications team to fix a problem that a server based application is having with response time. The administrator has examined the network portions of the data path and identified several possible problem areas. The applications team has simultaneously identified potential issues with the current release of software. The network administrator begins addressing the network issues while the applications team implements software patches.

Which statement applies to this situation?

**Changes to the network will reveal problems that are caused by the new patches.

Scheduling will be more difficult if the network and software teams work independently.

It will be difficult to isolate the problem if two teams are implementing changes independently.

Results from changes will be easier to reconcile and document if each team works in isolation.

46. Refer to the exhibit. R1 is performing NAT overload for the 10.1.1.0/24 inside network. Host A has sent a packet to the web server. What is the destination IP address of the return packet from the web server?

10.1.1.2:1234

172.30.20.1:1234

**172.30.20.1:3333

192.168.1.2:80

47. Which three guidelines would help contribute to creating a strong password policy? (Choose three.)

Once a good password is created, do not change it.

**Deliberately misspell words when creating passwords.

**Create passwords that are at least 8 characters in length.

**Use combinations of upper case, lower case, and special characters.

Write passwords in locations that can be easily retrieved to avoid being locked out.

Use long words found in the dictionary to make passwords that are easy to remember.

48. What will be the result of adding the command ip dhcp excluded-address 172.16.4.1 172.16.4.5 to the configuration of a local router that has been configured as a DHCP server?

Traffic that is destined for 172.16.4.1 and 172.16.4.5 will be dropped by the router.

Traffic will not be routed from clients with addresses between 172.16.4.1 and 172.16.4.5.

**The DHCP server function of the router will not issue the addresses between 172.16.4.1 and 172.16.4.5.

The router will ignore all traffic that comes from the DHCP servers with addresses 172.16.4.1 and 172.16.4.5.

49. Which two statements are true about IPv6? (Choose two.)

**Security options are build into IPv6.

IPv6 addresses require less router overhead to process.

IPv6 can only be configured on an interface that does not have IPv4 on it.

There is no way to translate between IPv4 addresses and IPv6 addresses.

**When enabled on a router, IPv6 can automatically configure link-local IPv6 addresses on all interfaces.

50. Refer to the exhibit. A network administrator has issued the commands that are shown on Router1 and Router2. A later review of the routing tables reveals that neither router is learning the LAN network of the neighbor router. What is most likely the problem with the RIPng configuration?

The serial interfaces are in different subnets.

**The RIPng process is not enabled on interfaces.

The RIPng network command is not configured.

The RIPng processes do not match between Router1 and Router2.

51. At what physical location does the responsibilty for a WAN connection change from the user to the service provider?

demilitarized zone (DMZ)

**demarcation point

local loop

cloud

52. Refer to the exhibit. A host connected to Fa0/0 is unable to acquire an IP address from this DHCP server. The output of the debug ip dhcp server command shows "DHCPD: there is no address pool for 192.168.1.1". What is the problem?

The 192.168.1.1 address has not been excluded from the DHCP pool.

**The pool of addresses for the 192Network pool is incorrect.

The default router for the 192Network pool is incorrect.

The 192.168.1.1 address is already configured on Fa0/0.

53. Which three functions are provided by the Local Management Interface used in Frame Relay networks? (Choose three.)

**exchange information about the status of virtual circuits

**map DLCIs to network addresses

provide flow control

provide error notification

provide congestion notification

**send keepalive packets to verify operation of the PVC

54. Which three items are LCP options that can be configured for PPP? (Choose three.)

**CHAP

**Stacker

IPCP

CDPCP

**Multilink

55. What are two main components of data confidentiality? (Choose two.)

checksum

digital certificates

**encapsulation

**encryption

CCNA Discovery 1 - Module 1 Exam Answers V.4

2008-05-16T00:24:00.000-07:00

CCNA Discovery 1 - Module 1 Exam Answers V.4

1. Which computer component is considered the nerve center of the computer system and is responsible for processing all of the data within the machine?
• RAM
• CPU
• video card
• sound card
• operating system

2. What are two advantages of purchasing a preassembled computer? (Choose two.)
• usually a lower cost
• exact components may be specified
• extended waiting period for assembly
• adequate for performing most general applications
• suited for customers with special needs

3. A user plans to run multiple applications simultaneously on a computer. Which computer component is essential to accomplish this?
• RAM
• NIC
• video card
• sound card
• storage device

4. Which adapter card enables a computer system to exchange information with other systems on a local network?
• modem card
• controller card
• video card
• sound card
• network interface card

5. What is the main storage drive used by servers, desktops, and laptops?
• tape drive
• hard drive
• optical drive (DVD)
• floppy disk drive

6. Which component is designed to remove high-voltage spikes and surges from a power line so that they do not damage a computer system?
• CPU
• surge suppressor
• motherboard
• hard drive

7. What are two examples of output peripheral devices? (Choose two.)
• printer
• speakers
• flash drive
• external DVD
• external modem

8. What two functions does a UPS provide that a surge protector does not ? (Choose two.)
• protects the computer from voltage surges
• provides backup power from an internal battery
• protects the computer from sudden voltage spikes
• gives the user time to phone the electrical company
• gives the user time to safely shut down the computer if the power fails
• provides backup power through a generator provided by the wall outlet

9. What is a word processor?
• It is a physical computer component.
• It is a program designed to perform a specific function.
• It is a program that controls the computer resources.
• It is a functional part of an operating system.

10. What is the purpose of the ASCII code?
• translates bits into bytes
• interprets graphics digitally
• translates digital computer language into binary language
• represents letters, characters, and numbers with bits

11. Why do servers often contain duplicate or redundant parts?
• Servers require more power and thus require more components.
• Servers should be accessible at all times.
• Servers can be designed as standalone towers or rack mounted.
• Servers are required by networking standards to have duplicate parts.

12. What are two benefits of hooking up a laptop to a docking station? (Choose two.)
• Mobility is increased.
• An external monitor can be used.
• Alternate connectivity options may be available.
• The keyboard can be changed to a QWERTY-style keyboard.
• More wireless security options are available.

13. Applications can be grouped into general use software or industry specific software. What are two examples of industry specific software? (Choose two.)
• CAD
• presentation
• spreadsheet
• word processing
• medical practice management
• contacts/scheduling management

14. Which three terms describe different types of computers? (Choose three.)
• operating system
• network
• laptop
• desktop
• Windows
• mainframe

15. How is a server different from a workstation computer?
• The server works as a standalone computer.
• The server provides services to clients.
• The workstation has fewer applications installed.
• The workstation has more users who attach to it.

16. How many values are possible using a single binary digit?
• 1
• 2
• 4
• 8
• 9
• 16

17. What measurement is commonly associated with computer processing speed?
• bits
• pixels
• hertz
• bytes

18. What can be used to prevent electrostatic discharge (ESD)?
• dry and non humid conditions
• carpeted floor
• grounding strap
• uncluttered work space

19. If a peripheral device is not functioning, what are three things you should do to solve the problem? (Choose three.)
• Use the testing functionality on the peripheral itself, if available.
• Verify that all cables are connected properly.
• Disconnect all cables connected to the computer except those connected to the peripheral.
• Ensure that the peripheral is powered on.
• Disconnect the peripheral and verify that the computer is operating normally.
• Reload the computer operating system.

20. Which two steps should be performed when installing a peripheral device? (Choose two.)
• Download and install the most current driver.
• Connect the peripheral using any cable and any available port on the computer.
• Connect the peripheral using an appropriate cable or wireless connection.
• Test the peripheral on another machine before installing it on the one where it will be used.
• Check the computer documentation to see if the peripheral vendor is compatible with the PC vendor.

21. In newer operating systems, how are system resources assigned by default when components are installed?
• manually assigned by the operating system
• manually assigned by the administrator
• statically assigned by the component to a preset resource
• dynamically assigned between the component and the operating system

CCNA Discovery 1 - Module 2 Exam Answers V.4

2008-05-16T00:22:00.000-07:00

CCNA Discovery 1 - Module 2 Exam Answers V.4

1. . An operating system is severely damaged. All data on the partition needs to be deleted, and all application software must be reinstalled. Which installation method should be used to correct the problem?
• clean install
• upgrade
• multi-boot
• virtualization

2. Which two statements should be included in a pre-installation checklist when upgrading an operating system? (Choose two.)
• Verify that the hardware resources have multiple partitions.
• Verify that the hardware resources meet or exceed the published minimum requirements.
• Complete a full backup of all important files and data.
• Overwrite any data currently contained on the drive to remove all contents.
• Verify that the hardware resources are certified to work with the existing operating system prior to upgrading.

3. Which three pieces of information must be specified on a computer to allow that computer to send and receive information across networks? (Choose three.)
• closest server
• operating system
• IP address
• subnet mask
• default gateway
• network card driver

4. Which two items must be unique to each computer and cannot be duplicated on a network? (Choose two.)
• partition
• file system
• computer name
• IP address
• operating system

5. Which method of interacting with an operating system involves typing commands at a command prompt?
• CLI
• GUI
• redirector
• kernel translator

6. What are three characteristics of an operating system that is released under the GPL (GNU Public License)? (Choose three.)
• full access to source code
• software often available free
• structured development cycle
• can be expensive to purchase
• limits what end-user can do with code
• support normally user-based and often free

7. What is the purpose of a default gateway?
• physically connects a computer to a network
• provides a permanent address to a computer
• identifies the network to which a computer is connected
• identifies the logical address of a networked computer and uniquely identifies it to the rest of the network
• identifies the device that allows local network computers to communicate with devices on other networks

8. Which two statements are true about drive partitions? (Choose two.)
• Partitions are necessary in multi-boot installations.
• A hard drive can be divided into an operating system partition and a data partition.
• User data is never overwritten when a drive is partitioned.
• A disk partition is a defined section of an operating system.
• Each partition requires a different file system type.

9. What occurs when computers are configured to receive their network configurations dynamically?
• Each computer receives a permanent IP address.
• A network administrator enters information on each computer.
• Each computer requests configuration information from a server.
• An NIC automatically provides configuration information to the computer and stores that configuration information.

10. What are two ways that a user can interact with an operating system shell? (Choose two.)
• CLI
• OS
• GUI
• NIC
• kernel

11. Which three resource specifications are given by the manufacturer to ensure that an operating system performs as designed? (Choose three.)
• required hard disk space
• type of accelerated graphics card
• recommended amount of RAM
• printer requirements
• processor type and speed
• type of keyboard

CISCO IOS CONFIGURATION

2008-05-15T14:35:00.000-07:00

CISCO IOS CONFIGURATION

Basic Router Commands

.
Mode-mode CISCO IOS : yaitu User Mode dan Previleged Mode yang akan praktikan praktekan satu per satu

Untuk masuk ke User Mode, praktikan cukup menekan tombol Enter, sehingga keluar Router>

Untuk mengetahui perintah apa saja yang disupport oleh mode ini tambahkan perintah “ ? “ pada Router>?

1. Router> show version
2. Router> show protocols
3. Router> show history

Masuklah kemode previleged dengan mengetikan perintah enable

Router> enable
Router#?

1. Router# show ip interfaces
2. Router# show ip interfaces brief
3. Router#show running-config

Untuk mengubah konfigurasi yang telah ada sebelumnya bisa menggunakan configure terminal untuk memasuki global configuration mode yang kemudian diikuti dengan baris-baris konfigurasi.

1. Router#conf t
2. Router(config )#

perintah exit akan diperlukan untuk keluar dari global configuration mode

Konfigurasi Router Interface
Tugas router adalah meneruskan paket paket dari sebuah network ke network yang lainnya. Sebuhungan dengan tugas tersebut, network interface harus dikonfigurasi sesuai dengan karakteristik-nya. Perintah interface pada mode konfigurasi global disediakan untuk mengkonfigurasi interface-interface pada router. Ada berbagai tipe interface yang dikonfigurasi dengan perintah ini antara lain: Ethernet, Token Ring, FDDI, serial ATM, BRI, dan tunnel. Dalam praktikum, hanya Ethernet dan Serial saja yang akan dibahas lebih lanjut.
1. Mengkonfigurasi Ethernet Interface
Perintah interface harus dijalankan pada mode konfigurasi global. Untuk memasuki mode konfigurasi global, gunakan perintah configure terminal, seperti yang telah dijelaskan sebelumnya.
Format perintah interface untuk memasuki mode konfigurasi interface untuk Ethernet
pada router yang hanya mempunyai satu slot adalah:
interface ethernet nomer-port
Beberapa jenis router memiliki banyak slot, seperti misalnya Cisco 2600,3600 dan 4000. Untuk router-router dengan banyak slot, format perintahnya adalah:
interface ethernet nomer-slot/nomer-port
Setelah memasuki mode konfigurasi interface dengan perintah di atas, barulah Ethernet
tersebut dapat dikonfigurasi sesuai dengan kebutuhan. Konfigurasi paling dasar yang dibutuhkan agar Ethernet dapat meneruskan paket-paket adalah IP address dan subnet mask.
Format konfigurasinya adalah:
ip address IP-address subnet-mask
Contoh konfigurasi Router1 interface ethernet 0 (pada topology Boson default)

1. Route1r# configure terminal
2. Router1(config)# interface ethernet 0
3. Router1(config-if)# description LAN pada Lab Akatel
4. Router1(config-if)# ip address 192.168.0.1 255.255.255.0
5. Router1(config-if)# no shut
6. Router1(config-if)# exit
7. Router1(config)# exit
8. Router1#

Perintah interface ethernet 0 pada baris ke 2, masuk ke mode konfigurasi interface ethernet 0
Perintah description pada baris ke 3 , memberikan deskripsi singkat tentang interface
Perintah ip address pada baris ke 4, memberikan no ip ke interface
Perintah no shut (no shutdown) pada perintah baris ke 5 diatas mengintrusikan bahwa interface tersebut langsung diaktifkan

Contoh konfigurasi Router2 interface ethernet 1 (pada topology Boson default)

1. Route2r# configure terminal
2. Router2(config)# interface ethernet 0
3. Router2(config-if)# description LAN pada Lab Akatel
4. Router2(config-if)# ip address 192.168.0.2 255.255.255.0
5. Router2(config-if)# no shut
6. Router2(config-if)# exit
7. Router2(config)# exit
8. Router2#

Uji Koneksitas Router dengan PING

Ping lah Router1 ke Router2
Router1# ping 192.168.0.2

Menampilkan ringkasan status IP interface Router1

Router1# show ip interface brief

Menampilkan ringkasan status IP interface Router2

Router2# show ip interface brief

2. Mengkonfigurasi Serial Interface
Serial interface adalah interface yang seringkali digunakan untuk koneksi ke WAN (Wide Area Network). Koneksi serial membutuhkan clocking untuk sinkronisasi. Dan oleh karena itu, hubungan serial ini harus mempunyai 2 sisi, yaitu DCE (data circuitterminating equipment) dan DTE (data terminal equipment). DCE menyediakan
clocking dan DTE akan mengikuti clock yang diberikan oleh DCE. Kabel DCE mempunyai koneksi female (perempuan), sedangkan kabel DTE mempunyai koneksi male (jantan). Pada prakteknya, DCE biasanya disediakan oleh service provider yang biasanya adalah merupakan koneksi ke CSU/DSU. Router sendiri biasanya hanyalah berperan sebagai DTE sehingga router tersebut tidak perlu menyediakan clocking. Walaupun demikian, cisco router juga bisa berperan sebagai DCE yang menyediakan clocking. Fungsi ini biasanya dipakai untuk uji coba router dimana kita bisa menghubungkan 2 buah router back to back sehingga salah satu router harus berfungsi
sebagai DCE agar koneksi bisa terjadi.

Contoh konfigurasi interface serial sebagai DTE

1. Router # configure terminal
2. Router(config)# interface serial 0
3. Router(config-if)# description Lab komp Akatel
4. Router(config-if)# ip address 172.16.158.1 255.255.255.0
5. Router(config-if)# bandwith 64
6. Router(config-if)# exit
7. Router(config)# exit

Contoh konfigurasi interface serial sebagai DCE

1. Router # configure terminal
2. Router(config)# interface serial 0
3. Router(config-if)# description Lab Cisco sebagai DCE
4. Router(config-if)# ip address 172.16.158. 255.255.255.0
5. Router(config-if)# bandwith 64
6. Router(config-if)# clock rate 64000
7. Router(config-if)# exit
8. Router(config)# exit

1. Uji Koneksitas Router 2 dengan Router 4
2. Menampilkan ringkasan status IP interface Router2
3. Menampilkan ringkasan status IP interface Router4

C. Mengamankan Router dengan Password
Untuk menyulitkan orang yang tidak berhak mengubah dan mengacau konfigurasi router, maka router tersebut perlu dilindungi dengan kata sandi (password).
Password untuk mode priviledge
Setelah user menuliskan password dengan benar untuk mendapatkan akses ke router
baik melalui jaringan ataupun console, maka user akan memasuki user mode. Jika password untuk mode priviledge dikonfigurasi, maka user juga harus menuliskan password lagi untuk masuk ke mode itu. Perintah yang digunakan untuk memberi password pada mode ini adalah enable password, atau enable secret.
Perbedaan antara kedua perintah tersebut adalah bahwa perintah enable secret membuat
password-nya terenkrip sedangkan enable password tidak. Kedua perintah tersebut juga bisa dituliskan kedua-duanya dalam mode konfigurasi global, dan keduanya juga bisa mempunyai password yang berbeda. Namun jika keduanya diletakkan pada konfigurasi, maka password pada enable secret yang akan digunakan untuk memasuki privileged mode.
Mengkonfigurasi enable password dari mode priviledge

1. Route1r#conf t
2. Router1(config)#enable password rahasia

Mengkonfigurasi enable secret dari mode priviledge

1. Router1#conf t
2. Router1(config)#enable secret rahasiabanget

Melihat konfigurasi Router (harus dari mode priviledge)

* Router1 (config)# exit
* Router 1#show running-config

Configuring Routing Protocols

2008-05-15T14:31:00.000-07:00

Configuring Routing Protocols

Routing protocols serve one function: To let nearby routers know how to get to them and the networks they serve. There are two basic types of routing protocols: distance vector protocols and link state protocols.

The simplest protocols are perhaps those that classify as Distance Vector protocols. They base their routing decisions on the number of intermediate routers along a given path. This has the advantage of taking very few resources but has the disadvantages of not considering bandwidth or the load of the available link. They also suffer limitations when long distances are present. The path may be valid but because of the high metric, the routers decide that the remote host or network is unreachable. In addition, these types of protocols usually broadcast their entire routing tables at preset intervals. This can take quite a bit of time and consume considerable bandwidth. Protocols that fall under this classification are RIP, IGRP, and BGP.

Link State protocols function by maintaining a database of advertisements they have received from other routers called the link state database. This means that each router is wholly responsible for determining the best path to a given location from its point of view and already has an idea of an alternate path, if any, should the first path become unavailable.

I. Configuring RIP
The Routing Information Protocol (RIP) is perhaps the simplest of routing protocols. It functions by broadcasting its entire routing table to all participating networks once every 60 seconds for IP or once every 90 seconds for IPX. When a route is heard from a remote router, the metric is increased by one. This number cannot exceed 15. A metric of 16 describes an unreachable network.
The simplicity of this protocol means that there is very little that the router must do each update. This allows the processor to perform other tasks. At the same time, there is no database being maintained. Its all contained in the routing tables. This simplicity, however, requires increased bandwidth as the entire routing table must be sent across the network. In a large network, this can take considerable time. In addition, It is not uncommon for networks to be more than 15 hops apart. This means that end nodes will not be able to contact each other because the metrics surpass the "unreachable" point.
Configuration is a 3 step procedure. First, create a RIP process and determine if any other routing process (such as IGRP or OSPF) is to redistribute its routes into this one. Second, specify which networks will receive RIP broadcasts. Third, configure any non-broadcast neighbors.
A sample configuration might look like
```
router rip
redistribute igrp 1000
network 2.3.4.0
network 4.5.3.0
neighbor 4.5.5.2
neighbor 4.5.5.3
```
II. Configuring IGRP
The Interior Gateway Routing Protocol (IGRP) is a dynamic distance-vector routing protocol designed by Cisco Systems in the mid-1980s. The advantages of IGRP over RIP include the maximum diameter of the network. Networks over 15 hops are unreachable in a RIP controlled network. IGRP allows up to 100 hops by default and can be set to accept paths as far away as 255 hops.
IGRP uses a combination of user-configurable metrics including internetwork delay, bandwidth, reliability, and load. Unlike RIP, IGRP routes are shared in proportion to their cost to provide equal or unequal cost load balancing with up to 4 paths to a given destination. Equal or unequal cost can be specified with a variance factor. The variance determines how unequal paths can be when performing load balancing. A variance of 1 (the default) specifies load balancing only when all paths are of an equal cost. This behavior can be overridden with the "traffic-share" command. To permit only the path with the lowest cost to be used, specify "traffic-share min". "traffic-share balanced" is the default.
Basic IGRP configuration is very similar to that of RIP. An IGRP routing process must be created on the router and given a list of participating networks. IGRP also accepts an optional Autonomous System number. When running IGRP over a non-broadcast network, systems which will accept updates can be entered individually with the "neighbor" command, as in RIP. Interfaces included in the range of addresses specified with a network statement that should not participate in IGRP (an example would be if that interface is managed through some other protocol such as OSPF), it can be designated passive with the "passive-interface" statement.
Example configuration:
```
router igrp 1000
variance 3
network 203.4.22.0
network 204.103.24.0
neighbor 204.103.24.5
neighbor 204.103.24.6
neighbor 204.103.24.7
passive-interface Ethernet4/1
passive-interface Fddi3/0
```
III. Configuring Enhanced IGRP
Enhanced IGRP is a redesign by Cisco of IGRP. It is intended to overcome some of the limitations that became apparent when IGRP was put into heavy use. Principally, improvements concentrated on the convergance time. Towards that end, a new convergence algorithm, DUAL (Diffusing Update Algorithm) was introduced. Among the benefits gained by the new algorithm is a guarantee of loop-free routing tables where EIGRP is the controlling protocol. EIGRP also introduces partial updates. This allows fewer routing messages to be exchanged between routers which, in turn, consume less bandwidth, leaving the data path free for user data. Partial updates also allow the receiving router to spend less time recalculating routing tables since routes not included in the update do not have to be recalculated.
Two key features of EIGRP are support for variable-length subnet masks and arbitrary route summarization. This allows for the removal of "classfull" routes in favor of CIDR routes, reducing the size of the routing table as a whole and allowing for easier maintenance of routing tables. EIGRP is also capable of automatically summarizing routes into common routes when possible. This feature can be disabled by specifying "no auto-summary" in the EIGRP configuration. Additional summarization can be performed within the router configuration on a per interface basis by placing "ip summary-address eigrp" statements in the interface configuration commands to advertise a specific aggregate as belonging to a given autonomous system as shown below.
```
   interface Ethernet0
  ip summary-address eigrp 1234 201.200.8.0 255.255.224.0
```
The result of this command is that advertisements of networks within the 201.200.8.0 block are reduced to a single advertisement of the aggregate block. So rather than sending routes for 32 class C networks, as RIP would do, a single advertisement encompassing all 32 networks can be made instead.
Another addition to EIGRP is support for the exchange of hello messages. When an EIGRP process is started, the router will send out hello packets on all participating interfaces using multicast packets when appropriate. Once the router determines which other routers are participating in EIGRP, the process of exchanging updates can begin. This allows for routers to quickly determine when new routers are added to the network or when existing routers become unreachable.
Basic configuration of EIGRP does not differ significantly from that of IGRP except that the router configuration command requires an EIGRP process ID instead of the optional autonomous system number.
Like IGRP, EIGRP supports unequal cost load balancing. But because of EIGRP's rapid convergence, enabling this feature is not only desirable from a traffic standpoint, when enabled, the other paths are already in use so fall over time in the event of a failure is minimal. To ease the transition from IGRP to EIGRP, routes are automatically redistributed between the two protocols.
IV. Configuring OSPF
The Open Shortest Path First (OSPF) Protocol was designed by the IETF as an IGP expressly for use with TCP/IP networks belonging to a single Autonomous System. It is designed as a link state protocol and is scalable to all but the most complex networks.
OSPF operates by forming adjacencies between routers and creating a topological database containing information about the state of all the links in the OSPF network. This information includes weights placed on various interfaces based on the bandwidth of the link and the type of interface or placed there manually by the network administrator. The cost of an internal path is determined by calculating the sum of the cost of traversing each link in the database. The path with the lowest cost (shortest path) is chosen as the best route. If there are multiple paths with equal cost, OSPF will load balance across up to 4 of these paths.
This database is updated whenever an adjacency is formed or dropped. Because a complete picture of the network is maintained by every router, when an adjacency drops and the corrosponding link is no longer availible, a new path can quickly be chosen from information the router already has. However, because it must hold a complete copy of the topological database, the memory requirements are quite substantial.
On large networks, the number of links in the database can grow to immense proportions. In these cases, a single link change can have a significant impact on every router in the system. A link that is intermittantly availible and unavailible can lead to high processor use for all routers, diminishing the performance of the network. OSPF provides a method of segmenting the network into several areas. These areas act as described above and are connected to a "backbone" area (area 0). The area boundry routers, rather than propegating every link state advertizement (LSA) into the backbone, only propegate "summary" advertizements describing the area they are linked to. This summary advertizement describes the entire area database in a single message, thus reducing the computational overhead and memory usage. Dividing the network into areas also reduces the impact of a single router or interface changing states on the rest of the network. only the attached area must recalculate the paths through that router or interface.
Use of stub areas and route summarization between areas can also help to reduce the number of entries in the topological database and reduce the memory requirements and CPU requirements for recalculating paths when changes occur in the network even further. Stub areas do not receive external LSAs (those injected into OSPF via redistribution from another protocol, such as RIP) and do not have to maintain any link state records except those within the stub area.
Routers configured with OSPF discover other OSPF routers by multicasting or unicasting hello packets to all SPF routers (multicast address 224.0.0.5). These hello packets are used to form and maintain adjacencies between routers.
Adjacencies are formed automatically across point to point links. On multiaccess networks such as ethernet, a "Designated Router" (DR) is elected. This router forms adjacencies with all other routers on the multi-access network and is responsible for synchronizing the topological database. In addition, a backup designated router (BDR) is also selected. In the event of a failure which disconnects the DR from the network, the BDR takes over and a new BDR is elected. This reduces traffic across the network since each router does not have to form an adjacency with every other router. This also reduces the CPU usage on all other routers connected to this network when a router becomes unavailable. Which routers are DR and BDR can be determined with either "show ip ospf neighbors" or "show ip ospf interface &ltinterface>".
OSPF is enabled by creating an OSPF routing process and specifying a process ID. Which networks OSPF operates over is controlled by "network" statements (as in RIP or IGRP). At the same time, these networks are assigned an area number. Neighbors can be hinted at by using the "neighbor" statement. Note that a neighbor does not necessarily form an adjacency. The exec command "show ip ospf neighbor" can be used to determine which routers are viewed as neighbors and the state of the link (whether they are simple neighbors, adjacent neighbors, BDR, or DR.) A simple OSPF configuration is shown below.
```
 Interface Ethernet0/0
ip address 1.1.1.1 255.255.255.0
Interface Serial1/2
ip address 1.1.2.1 255.255.255.0
Interface Fddi2/0
ip address 1.1.3.1 255.255.255.0

router ospf 1234
network 1.1.1.0 0.0.0.255 area 1
network 1.1.2.0 0.0.0.255 area 2
network 1.1.3.0 0.0.0.255 area 0
```
This sequence of commands configures OSPF on the three interfaces listed assigning Ethernet0/0 to area 1, Serial1/2 to area 2, and Fddi2/0 to the backbone area (area 0). Note that the network statements require a wildcard mask and not a network mask.
OSPF also supports variable length subnetting and route sumarization though it must be configured manualy. Sumarization takes place between areas and into the OSPF backbone area. Configuration of summary networks is done at area border routers with the "area &ltarea ID> range &ltnetwork> &ltnetwork mask>" command. Using route sumarization can greatly decrease the size of the topological database and reduce the amount of recalculation that needs to be done when a route becomes inaccessible or other topological changes occur. The backbone area should not be sumarized. If all other areas are summarized properly, all the backbone area will contain is summary routes.
Similarly, sumarization can be done when another protocol is redistributed into OSPF with a "summary-address &ltnetwork> &ltnetwork mask>"
V. Configuring BGP
The Border Gateway Protocol (BGP) is another in the family of distance vector protocols. However, unlike most routing protocols, BGP views its paths in terms of Autonomous Systems (ASs). An AS is loosely defined as a collection of routers under common administration. For example, Primenet is one AS, MCI is another, AT&T a third, and so on. Each of these ASs has their own AS number, which is used in the BGP exchange. Primenet's AS number (ASN) is 3549, MCI is 3561, and so forth.
BGP functions by setting up peering sessions with neighboring routers. An important advantage of BGP over other protocols is the use of TCP to transmit update messages and maintain peering sessions. Because of this, these sessions are not intended directly to be a measure of the link integrity, but more to provide an idea of the health of the neighboring router. If the router becomes unreachable or stops responding, the peering session will drop and the routes received over that link will be deleted from the BGP tables and other routers subsequently informed.
This loss of conectivity can be caused by the router going down due to a failure or loss of power, a problem with the link the session is transmitting over, or simply congestion which causes BGP information packets to be dropped. With the explosion of the internet over the last several years, routers which experience repeated BGP or EGP neighbor state changes have become more problematic. This is usually caused by the router rebooting multiple times or by an intermittant link. Most recently, a cause of such problems has been routers simply being overwhelemd by update messages and being unable to maintain peering sessions as a result. The term coined to describe this repeated advertizement and deletion of routes is "route flap" or a router "flapping". The result is that neighboring routers (and quite probably routers two or three links downstream) being overwhelemd with these messages and spending all their time recalculating paths. The effect of this is that those routers' services are degraded until stability returns. It can even cause those routers to begin to "flap" as well as the number of updates goes beyond what that router is capable of processing, creating a cascade failure. A great deal of research and development is being done by many companies at a feverish rate to produce routers capable of handling these updates and many service providers have instituted policies designed to reduce the size of the routing tables to reduce flap or to protect themselves from flap by "dampening" routes that flap repeatedly in a given interval.
A BGP route contains only a few pieces of information. The first is the network that the route describes. Second, the AS path necessary to get to that destination. Third, the origin of the route (External BGP or EBGP, Internal BGP or IBGP, another Interior Gateway Protocol or IGP, or incomplete.) Fourth, the router ID of the advertizing router, and finally, the BGP next hop address.
BGP provides a simple, yet effective loop detection method. Simply, the AS path of the learned route is checked against the router's own AS number. If this number apears anywhere in the path, the route is unusable and is discarded.
There are also a few weights and metrics associated with a BGP route which are used to aid in the path selection process. The first is litterally known as a "weight" and is used only by the router which sets it. This weight is not propegated to other routers. The second is a "local prefference" value. This is propegated to all routers belonging to a single AS. The last value availible is a "metric" or "Multi Exit Descriminator" (MED). MEDs are advertized to EBGP neighbors and is used to hint at the best path into an AS. The MED is reset when the route is readvertized to a third AS.
The BGP path selection process is straight forward.
- If the next hop is inaccessible, do not consider it.
- Consider larger BGP administrative weights first.
- If the routers have the same weight, consider the route with higher local preference.
- If the routes have the same local preference, prefer the route that the local router originated.
- If no route was originated, prefer the shorter autonomous system path.
- If all paths are of the same autonomous system path length, prefer the lowest origin code (IGP <>
- If origin codes are the same and all the paths are from the same autonomous system, prefer the path with the lowest Multi Exit Discriminator (MED) metric. A missing metric is treated as zero.
- If the MEDs are the same, prefer external paths over internal paths.
- If IGP synchronization is disabled and only internal paths remain, prefer the path through the closest neighbor.
- Prefer the route with the lowest IP address value for the BGP router ID.
BGP configuration begins by creating a BGP process and listing the router's local ASN. Next, neighbors are listed with their ASNs. A router with the same ASN is identified as an iBGP peer and those with differing ASNs are eBGP peers. The following configuration establishes a BGP process with ASN 3549 and creates an iBGP session with router 1.2.3.4 and an eBGP session to router 2.3.4.5 with AS number 380.
```
  router bgp 3549
 neighbor 1.2.3.4 remote-as 3549
 neighbor 2.3.4.5 remote-as 380
```
Advertizements of reachable networks can be controlled by redistributing another protocol into BGP or by manualy configuring these networks as in the following example.
```
  network 1.0.0.0
```
The class A network 1.0.0.0 is placed in the iBGP routing tables and becomes eligible for advertizement to eBGP peers with an origin code of "IGP". In general, this is the prefered method of advertizing BGP networks as redistribution of other protocols into BGP results in the loss of information about those networks learned by the IGP and mutual redistribution can lead to routing loops.
In the normal case, BGP must synchronize with an IGP. This means that a route learned by an eBGP peer will not be readvertized to another eBGP peer until the IGP has propegated this route to all routers in the local autonomous system. This has the effect of making certain that the route is not used before all routers know about it, resulting in data loss and serving to stabalize the network somewhat. However, this can slow convergance when routes change and increase the size of the IGP tables. To disable synchronization, use the BGP "no synchronization" command. If redistribution is not used, synchronization must be disabled for BGP to function.
Beginning with BGP version 4, BGP supports CIDR and route summarization. Summarization is enabled by default and can be disabled using the "no summarization" command. Routes are summarized by creating aggregate addresses. This has the effect of advertizing a single supernet for multiple related routes when possible in addition to the individual routes. Using the "summary-only" option, these more specific routes can be surpressed.
router A:
```
  router bgp 3549
 neighbor 1.2.3.5 remote-as 3549
 network 1.2.0.0 mask 255.255.0.0
 network 1.3.0.0 mask 255.255.0.0
 network 1.1.8.0 mask 255.255.248.0
```
router B:
```
  router bgp 3549
 aggregate address 1.0.0.0 255.0.0.0 summary-only
 neighbor 1.2.3.4 remote-as 3549
 neighbor 2.3.4.5 remote-as 1111
```
In the preceding example, router A is configured with one iBGP peer and begins advertizing 3 subnets of the 1.0.0.0 class A. Router B configures one iBGP neighbor and one eBGP neighbor and summarizes routes learned from router A into a single advertizement which is sent to the eBGP peer.
Often, the closest path to a site may not be the best path, either because of bandwidth limitations or performance problems. The most direct way to prefer one neighbor's routes over another is to simply filter the advertizements to remove the unwanted routes. This can be done based on network prefix or AS path.
```
 router bgp 3549
neighbor 1.2.3.4 remote-as 1111
neighbor 1.2.3.4 distribute-list 1 in
neighbor 2.3.4.5 remote-as 2222
neighbor 2.3.4.5 filter-list 7 in

access-list 1 deny 10.0.0.0 0.255.255.255
access-list 1 permit any

ip as-path access-list 7 deny _5555$
ip as-path access-list 7 permit .*
```
The preceding example prevents neighbor 1.2.3.4 for advertizing that it can reach the network 10.0.0.0/8 and prevents neighbor 2.3.4.5 from advertizing that it can reach any path where ASN 5555 is the last ASN in the path. The as-path regular expressions are documented in the cisco documentation set and follow general regular expression rules. Note that access lists and route maps (as illustrated below) can be applied to either inbound or outbound advertizements.
Filtering advertizements is an easy way to determine how you want your network to route but it has one big drawback: if the primary route is down, the destination simply becomes unreachable. The filter prevents the secondary route from ever appearing in the first place. BGP provides two alternative ways of influencing the path selection process: weights and local prefference values.
```
 router bgp 3549
neighbor 1.2.3.4 remote-as 1111
neighbor 1.2.3.4 weight 300
neighbor 2.3.4.5 remote-as 2222
```
Configuring weights for all of a neighbor's routes requires no more than an additional statement in the BGP configuration, specifying the weight that should be assigned to these routes. If two neighbors advertize that they can reach the same network, the path with more weight will be selected.
It should be noted that the configured weight is only used by the router that sets it. If you want every router in your AS to prefer the same path, you can use a "route map" to set a local preference value. This value will be propegated to every iBGP peer that receives this route. Routes with no local preference set receive a local preference of 100. Higher local preferences are selected first.
```
 router bgp 3549
neighbor 1.2.3.4 remote-as 1111
neighbor 1.2.3.4 route-map set-weight in

route-map set-weight permit 10
set local-preference 200
```
Route maps allow complex filtering to be performed based on multiple conditions. There can be multiple statements underneath a route-map to alter a variety of attributes. The routes altered can also be limited by further filtering the advertizements by using an access-list (prefix or AS path) to "match" a subset of the routes being processed. It is also possible to apply multiple policies to the same neighbor. These policies are ordered sequentially according to the number listed after the "permit" or "deny" statement. The following example illustrates some of these capabilities.
```
 router bgp 3549
neighbor 1.2.3.4 remote-as 1111
neighbor 1.2.3.4 route-map local-policy in
neighbor 1.2.3.4 distribute-list 25 in

route-map local-policy permit 10
match as-path 1
set weight 300

route-map local-policy permit 20
match ip address 20
set local-preference 125

route-map local-policy permit 30
set as-path prepend 1111

ip as-path access-list 1 deny _350_
ip as-path access-list 1 permit .*

access-list 20 permit 120.10.0.0 0.0.255.255
access-list 20 deny any
```
This example also demonstrates that it is possible to alter the AS path of a given route. By prepending the appropriate AS number, it is possible to increase the path length of a BGP route, making it further away.
One problem with running iBGP is the requirement of BGP for a "full mesh" within the AS (every router must establish a peering session with every other router). Clearly, this is not possible in all settings and can create problems when a great meny peering sessions must be maintained on a single router. There are ways to reduce the mesh needed to propegate iBGP routes and simplify the structure of the autonomous system. The first of these is router reflectors.
Normaly, when a route is received from one iBGP speaker, it is not readvertized to another. Route reflectors provide a way to permit this occurence. Each client's routes are reflected to every other iBGP router that the server peers with. The clients are configured as normal iBGP speakers. The server simply designates clients as such.
```
 router bgp 3549
neighbor 1.2.3.4 remote-as 3549
neighbor 1.2.3.4 route-reflector-client
neighbor 1.2.3.5 remote-as 3549
neighbor 1.2.3.5 route-reflector-client
```
With such a configuration, peering between 1.2.3.4 and 1.2.3.5 is not necessary since the route server reflects the routes received by each neighbor to the other neighbor.
Another method of reducing the iBGP mesh is to create a confederation, effectively splitting the single AS into several smaller autonomous systems. These "mini-ASs" must be fully meshed but only require one connection between themselves and other mini-ASs. Confederations allow the smaller ASs to exchange routes between themselves as if they were using iBGP (local preference values, MEDs, etc are all preserved). To the rest of the world, the confederation appears as a single AS.
```
 router bgp 65501
bgp confederation identifier 3549
bgp confederation peers 65502 65503
neighbor 1.2.3.4 remote-as 65501
neighbor 1.2.3.5 remote-as 65501
neighbor 2.3.4.5 remote-as 65502
neighbor 2.3.4.6 remote-as 65503
neighbor 2.3.4.6 weight 300
neighbor 5.5.5.5 remote-as 1050
neighbor 5.5.5.5 route-map set-preference in
```
The local router is identified to the confederation as 65501. It is identified to non-confederation peers as ASN 3549. AS 65502 and 65503 are also members of this confederation. iBGP connections are configured between this router and the routers listed as 1.2.3.4 and 1.2.3.5. Peering sessions are established between this router and the confederation members 65502 and 65503. There is also an eBGP session established with router 5.5.5.5 with the remote ASN of 1050. This router will view the peer as AS 3549 and not be aware of 65501, 65502, or 65503. This router sets the local preference for AS 1050 and passes it to every iBGP peer and the rest of the confederation.
VI. Exchanging Routes Between Protocols
It is entirely possible (and often necessary) to exchange routes learned by one protocol into another. An example of such a case would be where a network cannot be managed by a single protocol due to software or hardware limitations. Such limitations might be due to a lack of adequate memory in the router or a router that does not support the desired protocol. It might also be the case that functionality provided by one protocol is not sufficient in a particular area of the network and another protocl must be left to manage that section. In order for the rest of the network to know the routes to those other sections and vice versa, the protocols must exchange routing information.
Assume that a collection of routers only speak RIP but that these routes need to make their way into EIGRP and the EIGRP routes neet to be injected into RIP. Redistribution would occur at the boundry router and would look similar to the example that follows.
```
 router eigrp 10
redistribute rip

router rip
redistribute eigrp 10
```
The routes that one protocol learns are now visible to the other. But assume for a momment that the network running RIP only needs to default out to the network running EIGRP. In this case, the RIp network does not need to see the eigrp routes and the redistribution is only necessary into EIGRP. This saves memory on the RIP routers, network bandwidth, calculation time, etc and generaly makes things run cleaner. It also eliminates one problem with the configuration shown above. Once the routes from the RIP process are distributed into the EIGRP process, they become EIGRP routes and are eligigle to be distibuted BACK into the RIP process. This can create routing loops and destroy the connectivity of the network. When using such mutual redistribution, careful filtering is required to avoid such pitfalls. This filtering is set by using a route-map along with the redistribution statement.
In this example, the RIP network needs to learn the EIGRP routes and send its routes back. The RIP network manages routes for 10.2.3.0/24 and 10.2.4.0/24. The EIGRP network routes the rest of the 10.0.0.0/8 network.
```
 router eigrp 10
redistribute rip route-map rip-in

router rip
redistribute eigrp 10 route-map eigrp-in

route-map rip-in permit 10
match ip address 20

route-map eigrp-in permit 10
match ip address 21

access-list 20 permit 10.2.3.0 0.0.0.255
access-list 20 permit 10.2.4.0 0.0.0.255

access-list 21 deny 10.2.3.0 0.0.0.255
access-list 21 deny 10.2.4.0 0.0.0.255
```
This effectively limits the routes seen by the two processes. This is not the only method of filtering, however. Assuming the same access lists, the following two configurations would also work.
```
 router rip
redistribute eigrp 10 metric 2
distribute-list 21 in

router eigrp 10
redistribute rip
default-metric 1000 100 250 100 200
```
Or
```
 router rip
redistribute eigrp 10
distribute-list 20 out

router eigrp 10
redistribute rip
distribute-list 21 out
```
These two examples accomplish the same end result as the route-map example above. In addition, two other features are demonstrated. The first is the setting of a metric on the inbound routes. The second is a default metric used when the metric cannot properly be calculated or when information is missing (as in the redistribution). This information is specific to the protocol and the command refference guide should be used to determine which values to use.

Configuring Access Lists and Network Security

2008-05-14T14:27:00.000-07:00

Configuring Access Lists and Network Security

Once the router's interfaces are configured, a momment should be taken to determine if any of these interfaces connect to "secure" networks. These networks can be those that connect corporate workstations with the rest of your network or perhaps the rest of the internet. They could also be networks which house servers that provide specific services to the internet community but which you would like to protect as much as possible. A good example of such a server is a WWW server of SMTP gateway. The general public needs to be able to view your web page and send you mail but they do not need to be able to connect interractively to those servers. Other uses for access control could be in protecting parts of your corporate intra-net from other parts of your company. For example, if you have a Research and Development department, it is unlike that you'll be giving your sales staff access details on top secret projects. Likewise, you don't want your Research and Development department making some clever modifications to your accounting servers.

The traditional way of protecting such servers is with access lists. Access lists filter Internet traffic and determine if a packet is permitted to pass into or out of the network. Ideas about how access lists should be designed, where they should be placed, and how physical networks should be structured to allow propper filtering without overloading network links and the routers they connect varry considerably. Some corporations choose to invest in commercial "fire wall" products while others will implement minimal access controls at all. Still others will invest in the hardware necessary to service access lists at two levels (one router that blocks access to itself and the interrior router and a second, the interrior router, that blocks access to itself, is only accessible from inside or even only from its console, and provides primary access list control. This router generally does nothing else besides filtering packets and sending them to its default router or a local host.)

Which method you choose depends on your needed level of security, your budget, and the particular application for which the protection is needed. The decisions that lead to the various scenarios are beyond the scope of this document, however. This section intends to focus solely on access list design and implementation for the general case.

Cisco has created two different classes of access lists within its routers. The first, the standard access list, filters only on source address. If numbered access lists are being used (IOS 11.1 and earlier did not support named access lists), than these lists would be numbered from 1 to 99. The second type of access list, the extended access list, is numberes from 100 to 199 and is capable of filtering based on source address, destination address, protocol, protocol port number, and a myriad of other features not necessarily applicable to general IP traffic.

Once an access list is created, it must be tied to an interface in order to be used. The interface configuration considers a filter list to be an "access group". The access group can be applied either inbound or outbound with respect to the interface. For example:

 Interface Serial0
ip access-group 101 in
ip access-group 6 out

This group of commands specifies that traffic coming into Serial0 must be processed through extended access list number 101 and that outbound traffic must pass through standard access list 10 before leaving the interface.

Standard access lists are configured by specifying a list number, wether a match on this entry will result in traffic being permitted or denied, and the host or network which is being filtered and the mask associated with it (if it is a network or subnet).

 access-list 10 permit 234.5.6.12
access-list 10 deny 5.10.10.32 0.0.0.31
access-list 10 permit 5.10.0.0 0.0.255.255
access-list 10 permit 123.234.0.0 0.0.0.255

The above example creates access list 10 and configured 4 entries. The first line permit all traffic with a source IP address of 234.5.6.12. Note that when a host IP address is listed, no mask needs to be associated with it. The second line denies all traffic from the subnet 5.10.10.32/27. One thing to observe about access lists is that instead of netmasks, they use what Cisco calls "wildcard masks." These masks function very similarly to netmasks with one important difference. Network masks operate from left to right. Wildcard masks operate from right to left. Therefore, when looking at the above configuration line, what the wildcard mask is matching is the 32 addresses that begin at 5.10.10.32. (Since zero is a valid mask, it counts as one address. Hence 31 is used in the mask instead of 32.)

The remaining two lines permit traffic from 5.10.10.0.0/16 and 123.234.0.0/24 respectively. On first glance, a newcommer to access lists might think that the only thing getting denied to this network is the second line and that the permit lines are unnecessary. Access lists, though, are designed to be selectively permissive, not to selectively deny traffic. As a result, an implicit deny exists at the end of this access list. (More propperly, anything that does not explicitly match an entry in the access list is dropped.)

There are a couple of other important things to consider when creating access lists. First, order is extremely important. Since access lists function through "short circuit" processing (bail out when a match is found), those entries that are most likely to match traffic should be listed first. IP access list processing is very processor intensive. By listing frequent matches first, processor utilization is kept to a minimum. Note also lines 2 and 3 of the above example. They state, collectively, that all traffic from 5.10.0.0/16 is to be permitted EXCEPT for those hosts in 5.10.10.32/27. If line 2 (the deny statement) were listed AFTER line 3, than the denial would have no effect. The traffic would be permitted as a result of line 3 and those hosts you intended to block would be allowed access. When you create access lists, you should review them very carefully to be certain that no mis-ordering has occured.

The second thing to watch for when creating access lists is the fact that changes to a cisco router take effect immediately upon entry. It is a fact that most access lists are not the stagnant, unchanging creatures we would like them to be. From time to time, they will require modification. Modifying an access list means deleting the existing list and recreating it with the appropriate changes. When an interface is configured to refference an access list that does not exist, the traffic will, by default, be permitted through. However, when you create that access list, the implicit denial at the end can result in your configuration session being filtered out. As a matter of policy, it is good practice to remove the refference to the access list from the interface before modifying the access list. (via "no ip access-group 123" or whatever access list you intend to refference.)

Building extended access lists is somewhat more complicated and requires a few more steps. Since extended access lists filter based on both the source and destination IP address, two parts to each entry are needed. The following is a brief example of an extended access list for IP.

 access-list 101 permit tcp any any established
access-list 101 permit tcp any 204.34.5.25 host eq 80
access-list 101 permit ip 203.45.34.0 0.0.0.255 204.34.5.0 0.0.0.255
access-list 101 permit tcp 203.44.32.0 0.0.0.31 204.34.5.0 0.0.0.255 eq telnet
access-list 101 permit tcp any 204.34.5.10 eq smtp

This access list allows all TCP connections with the established flag, allows any user to get to the host 204.34.5.25, tcp port 80 (which is the http port), all IP protocols from 203.45.34.0/24 to reach any host within the 204.34.5.0 class C, all hosts within 203.44.32.0/27 can telnet into any host on the 204.34.5.0, and allows all hosts to connect to the smtp port on host 204.34.5.10.

A few notes about this access list. The first line is important. It allows all packets which have had the TCP established flag set. This means two things. First, all outbound connections will be able to have the return traffic pass back through the access list. This is important. Since outbound tcp connections come from random ports above 1024, it is not possible to filter explicitly for outbound connections. The established field takes care of that. Second, an inbound TCP connection only needs to have the first packet pass beyond this point in the access list. Once the connection has been opened, the remaining traffic will have the established flag set and will not have to again pass through the entire access list.

The second line also demonstrates that when a source or destination is used, the wildcard mask can be replaced with the word "host" to indicate this. It also gives an example of filtering based on a destination port. The third line matches all IP protocols (TCP, UDP, ICMP, etc. Everything that gets encapsulated in an IP packet.) The source and destination network number and wildcard mask pairs function the same as in standard access lists. The fourth line shows that, on well known services, the port number can be replaced with the name of the service.

There is one last important thing to consider when creating access lists however. Many services depend on other services in order to function. For example, you can't just permit telnet connections without permitting DNS packets to get through as well. You often won't be able to telnet out unless telnet ident requests can come back into your network. If you wish to synchronize the clocks on your computer systems to other systems, you likely need to permit NTP packets (both TCP and UDP) to pass through. For this reason, carefull consideration is needed when creating access lists. It is all too easy to overlook one or two key services when creating lists. As network administrators gain experience with access controls, these omissions become more rare, but they still occur with annoying frequency. Access lists should be tested throroughly once they are in place. Both to be certain that necessary traffic is permitted through the list as well as to be certain that unwanted traffic does not.

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