在Cisco资格认证的培训计划中，本书是一本为参加“Csico认证网络助理CCNA”的资格认证考试的人员编写的相当完备的辅导教材。书中，除了详细介绍了什么是CCNA，如何获得CCNA之外，主要介绍的是CCNA考试中所涉及的必需掌握的技术内容；包括Cisco的互联网操作系统(IOS)软件、OSI参考模型、局域网和局城网交换机、网络协议、路由技术、网络安全、广域网协议等。\r\n\r\n 本书虽是围绕如何帮助读者通过CCNA的认证考试来编写的，但其所涉及的内容也是网络技术方面具有普遍意义的一些问题，因此，不参加CCNA考试的读者使用本书也将获益非浅。\r\n\r\n 本书附有光盘，盘内有样题并可帮助读者根据自己需要随机拼成模拟试题进行自测。\r\n
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Introdudion xv \r\n\r\n 1 What Is CCNA? 2 \r\n\r\n 2 Understanding Cisco's Intenetwork Operating 'System .{IOS) Software 94 \r\n\r\n 3 Underetandina the OSI.Raferenoe Model 70 \r\n\r\n 4 Understanding LANs and LAN Switching 120 \r\n\r\n 5 Network Protocols: Understanding the TCP/IP Suite and Novell NetWare Protocols 168 \r\n\r\n 6 Understanding Routing 262 \r\n\r\n 7 Understanding Network Security 334 \r\n\r\n 8 WAN Protocols: Understanding Point-to-Point, Frame Relay, and ISDN 380 \r\n\r\n 9 Scenarios for Final Preparation 472 \r\n\r\n A Decimat to Hexadecimal and Binary Conversion Table 530 \r\n\r\n B Answers to the 'Do I Know This Already?' Quizzes and Q&A Sectiorts 540 \r\n\r\n Index 595 \r\n\r\n \r\n
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Introduction : Overview of Certification and How to Succeed
Professional ceHifications have been an impoHant pan of the computing industry for many years and will continue to become more and more important. Many reasons exist for these cenifications, but the most popularly cited reason is that of credibility. All other considerations held equal, the cenified employee/consultant/job candidate is considered more valuable than one who is not.
Cisco Certifications: Training Paths and Exams
The Cisco Certified Internetwork Expen fCCIE) certification program has been available since the early'90s. This long-standing certification has maintained a high degree of credibility and is recognized as a cenification that lives up to the name "expert;' The CCIE centification process requires passing a computer based test and then a two-day hands-on lab. Recertification is required every two years to ensure that the individual has kept skills up-to-date.
Many problems were created by having one highly credible, but difficult to pass,certification. One problem was that there was no way to distinguish between someone who is almost ready to pass CCIE and a novice. The CCIE lab test is meant to prove that the individual not only has mastery of many topics, but the ability to lean and unravel situations quickly and under pressure. Many highly respected engineers have failed the CCIE lab on the first try. Employers wanting to reward employees based on cenification, employers looking at prospective new employees, and network managers trying to choose between competing consulting companies have had too few Cisco-related cenifications on which they could base their decisions.
In an effort to solve these problems, Cisco Systems has created several new "Cisco Career Cenifications." Included.in these new cenifications is a series of cenifications related to routing and switching. The Cisco Certified Network Associate (CCNA) certification, accomplished by passing a computer-based exam, is one of these new certifications oriented toward routing and switching. CCNA is the first cenification in this series. If you understand the protocols listed in the table of contents, plus how they apply to the network diagramed in Figure 1-1, then you are a candidate who should be ready for the CCNA exam.
The WAN links in ale Figure I-l are Frame Relay, point-to-point serial, and ISDN links. The LANs are typically Ethernet. with LAN switches in some cases.
The CCNA exam is used to pmve mastery of tlle features used in typical small networks. CCNA certification is required before attempting CCNA and CCDP certifications. Figure I-2 lists lists various Cisco cenifications relating to routing and switching, along with the exams required.
Some reasons for taking the CCNA exam are as follows:
1. To prove your mastery of basic internetwork concepts.
2. To create a more impressive entry in your resume.
3. To prove that beyond simply taking a Cisco cerfified course. you understand the topics in the class.
4. To demonstrate that you have equivalent experience and expenise to those who have taken ale Cisco certified courses.
5. To obtain a Cisco cenification while you gain the experience needed to pass the CCIE Routing and Switching or CCIE ISP Dial cenifications. (Unless you want to shoot for the stars and take a CCIE test now. CCNA is the only first step toward certification involving routing and LAN switching.)
6. To encourage self-discipline in your study as you try to become CCIE cenified.
7. As a stepping stone to the CCNP and CCDP cenifications.
8. For consultants, to provide a marketing edge compared to your competitors by asserting that a Cisco certified individual will be working with a particular prospective client.
Two suggested training paths are outlined on Cisco's Web site and include suggested courses that will prepare you to pass the exam. These paths are also described later in this chapter, along with two other training paths.
The Cisco Certified Networking Professional (CCNP) exam is used to prove mastery of more complex networks. In this case, complex means topics covered in the prerequisite courses. Like CCNA, the CCNP cenification is oriented toward proving the skills needed to impleHleht intemetworks. Most of the same reasons for wanting to become CCNA cenified are also true for CCNP. CCNA certiBeation is a prerequisite to bking the CCNP exam.
When this book went to press, the courses suggested in ate training path defined by Cisco for CCNP were as follows:
1 A training path leading to CCNA cenification
2. The Advanced Cisco Router Configuration (ACRC) course
3. The Cisco LAN Switching Course (CLSC) course
4. The Configuring, Monitoring, and Troubleshooting Dial-up Services (CMIB) course
5. The Cisco Intemetwork Troubleshooting (CIT) course
The Cisco Certified Design Associate (CCDA) exam is used to prove mastery over network design issues for basic networks. It is similar to CCNA but is focused on design issues. This certification is particuly important for those. with presales oriented jobs.
When this book went to press, the courses suggested in the training path defined by Cisco for CCDA were as follows:
1. The Internetworking Technology Multimedia (ITM) CD-based course
2. The Designing Cisco Networks (DCN) course
The Cisco Certified Design Professional (CCDP) exam is used to prove mastery over design issues for more advanced networks. This cenification proves mastery of design issues in complex networks. In this case, complex means topics covered in the prerequisite courses. This cenification is particularly imponant for those with presales oriented jobs. CCDA and CCNA certification are prerequisites to taking the CCDP exam.
When this book went to press, the courses saggested in the training path defined by. Cisco for CCDP were as follows:
1 . A training path leading to CCDA and CCNA certification
2. The Advanced Cisco Router Configuration (ACRC) course
3. The Cisco LAN Switching Course (CLSC) course
4. The Configuring, Monitoring, and Troubleshooting Dial-up Services (CMTD) course
5. The Cisco Intemetwork Design (CID) course
A Few Wordson the Various Cisco Certifications
You should note the following when considering CCNA, CCNP, CCDA, and CCDP Cisco routing and switching cenifications:
Most people will not pursue all four of these certifications: CCNA, CCNP, CCDA and CCDP-Most people will follow a track of getting CCNA and then either focus on the design cenifications or the implementation certifications.
Certification exams cover the content taught in Cisco Systems Certified Course--There is a definite benefit to taking the courses suggested by Cisco before taking the exam.The courses are not required for cenification, however.
The old CCIE is now CCIE-B/S-Cisco added the designation R/S for "routing and switching;' which includes both LAN and ATM switching. This is the CCIE of old. CCIE-ISP covers dial issues in more depth, as well as exterior routing protocols.CCIE-WAN, which entails a separate career path of recommended courses and exams,covers WAN switching and voice.
Only the CCIE certifications require a hands-on lab exam-CCIE-R/S, CCIE-ISP,and CCIE-WAN all require passing a hands-on lab exam after passing a written (computer-based) exam. Recenification for CCIE of any kind currently does not require a hands-on lab, but rather a more detailed written test on an area of specialization.
Recertification is not (yet) requied for CCNA, CCNP, CCDA, and CCDP--Because these cenifications were announc.ed in early 1998, there is not yet a need for recertification rules. In my opinion, Cisco will eventually require recertification for these. probabl with a written (computer-based) test.
In the future, CCNA might be required before taking CCIE-Today, you can take the CCIE written exam at any time. In my opinion, the reason these new certifications are not required before taking the CCIE exam today is that there would be complaints from people who have prepared for CCIE, but would have then to back up and take other tests. If my theory is true. it seems reasonable to assume that one day Cisco will require CCDP or CCNP cenification before taking the CCIE written and lab exams. Of course, the CCNP and CCDP certifications require CCNA certification first. It will be interesting to see if my predictions come true"
There is also a WAN Switching Career Certifications path-There is a whole other set of cenifications with the acronym WAN in the tide, which refer to the WAN switching topics and the functions of what was once the Stratacom product line (which was bought by Cisco). CCNA-WAN, CCNP-WAN, CCDP-WAN, and CCIE-WAN are the cenifications; only a CCDA-WAN is missing as compared to the routing/switching certifications. These cenifications are similar in concept to the others, but because the technology concerned is WAN switching, there are different exams and comses for the Career Certification levels. Please see Cisco's Web site for more details.
Objectives
The objective of this book is to help you fully understand, remember, and recall all the details of the topics covered on the CCNA exam. When that objective is reached. passing the CCNA exam should follow. The CCNA exam will be a foundation for most people as they progress through the other Cisco certifications; passing the exam because of a thorough undersstanding and recall of the topics will be incredibly valuable at the next steps.
This book will help you pass the CCNA eum, by doing the following:
.Helping you discover which test topics you have not mastered
.Providing explanations and information to fill in your knowledge gaps
.Supplying exercises and scenarios wkich enhance your ability to recall and deduce the answers to test questions
.Providing practice exercises on the topics and ale testing process via oitline test questions(delivered on the CD)
Who Should Read This Book?
This book is not designed to be a general networking topics book, although it can be used for that purpose. This book is intended to uemendously increase your chances of passing the CCNA exam. Although others may benefit from using this book, the book is written assuming you want to pass the exam.
So why should you want to pass CCNA? To get a raise. To show yom manager you are working hard to increase your skills. As a requirement from your manager.before he will spend money on another course. As a resume enhancer. Because you work in a presales job at a reseller and want to become CCDA and CCDP certified. To prove you know the topic. if you learned via on-the-job training (OJT) rather than from taking the prerequisite classes. Or one of many other reasons .
Others who may want to use this book are those considering moving beyond Cisco's ICRC(Inuodnction to Cisco Roater Configuration) course to take Cisco's ACRC (Advanced Cisco Router Configmation) or CLSC (Cisco LAN Switch Configuration) courses. If you can answer a high percentage of the questions in this book, you are ready for those courses!
Have you Mastered All the Exam Objectives?
The exam will test you on a wide variety of topics; most people will not remember all ale topics on the exam. Because some study will be required, this book focuses on helping you obtain the maximum benefit from the time you spend preparing for dle exam. There are many sources for the information covered in the exam; for example, you coald read the Cisco Documentation CD. However, this book is the most effective way to prepare for the exam.
You should begin your exam preparation by reading Chapter 1 and spending ample time reviewing tbe exam objectives listed there. Check ont Cisco's "Cisco Connection Online" Web Site (http://www.cisco.com) for any future changes to the list of objectives.
Wendell Odom. CCIE. is the Technology Director of Lacidar Unlimited. Inc, a networking consulting and training company in Atlanta, Ceorgia. In this role, Wendell provides both expert advice about many aspects of building networks, and full design and implementation assistance for large projects. Wendell is CCIE #1624 and a Cenified Cisco Systenls Instnxctor and has taught varions Cisco cenification courses including Introduction to Cisco Router Configuration (ICRC). Advanced Cisco Rputer Config
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