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  1. 1. CCNA Cisco Certified Network Associate Study GuideCopyright ©2000 SYBEX , Inc., Alameda, CA
  2. 2. CCNA™ Cisco Certified ®Network Associate Study Guide Second Edition Todd Lammle San Francisco • Paris • Düsseldorf • Soest • LondonCopyright ©2000 SYBEX , Inc., Alameda, CA
  3. 3. Associate Publisher: Neil EddeContracts and Licensing Manager: Kristine O’CallaghanAcquisitions & Developmental Editor: Linda LeeEditors: Susan Berge, Sally Engelfried, Rebecca Rider, and Marilyn SmithProduction Editor: Lisa DuranTechnical Editors: Patrick Ramseier and Eric GunnettBook Designer: Bill GibsonGraphic Illustrator: Tony JonickElectronic Publishing Specialist: Maureen Forys, Happenstance Type-O-RamaProofreaders: Molly Glover, Jennifer Campbell, Laurie O’Connell, and Camera ObscuraIndexer: Matthew SpenceCD Coordinator: Kara SchwartzCD Technician: Keith McNeilCover Designer: Archer DesignCover Photographer: Tony StoneSYBEX and the SYBEX logo are trademarks of SYBEX Inc. in the USA and other countries.The CD interface was created using Macromedia Director, COPYRIGHT 1994, 1997-1999 Macromedia Inc. For moreinformation on Macromedia and Macromedia Director, visit study guide and/or material is not sponsored by, endorsed by or affiliated with Cisco Systems, Inc. Catalyst®, Cisco®,Cisco Systems®, Cisco® IOS, Cisco Systems Networkng Academy™, CCDA™, CCNA™, CCDP™, CCNP™, CCIE™,CCSI™, the Cisco Systems logo and the CCIE logo are trademarks or registered trademarks of Cisco Systems, Inc. in theUnited States and certain other countries. All other trademarks are trademarks of their respective owners.TRADEMARKS: SYBEX has attempted throughout this book to distinguish proprietary trademarks from descriptive termsby following the capitalization style used by the manufacturer.The author and publisher have made their best efforts to prepare this book, and the content is based upon final release soft-ware whenever possible. Portions of the manuscript may be based upon pre-release versions supplied by software manu-facturer(s). The author and the publisher make no representation or warranties of any kind with regard to the completenessor accuracy of the contents herein and accept no liability of any kind including but not limited to performance, merchant-ability, fitness for any particular purpose, or any losses or damages of any kind caused or alleged to be caused directly orindirectly from this book.First edition copyright © 1999 SYBEX Inc.Copyright © 2000 SYBEX Inc., 1151 Marina Village Parkway, Alameda, CA 94501. World rights reserved. No part of thispublication may be stored in a retrieval system, transmitted, or reproduced in any way, including but not limited to photo-copy, photograph, magnetic, or other record, without the prior agreement and written permission of the publisher.Library of Congress Card Number: 00-102850ISBN: 0-7821-2647-2Manufactured in the United States of America10 9 8 7 6 5 4 3 2 1 Copyright ©2000 SYBEX , Inc., Alameda, CA
  4. 4. Software License Agreement: Terms and ConditionsThe media and/or any online materials accompanying this book available from SYBEX in any other form or media than thatthat are available now or in the future contain programs and/or enclosed herein or posted to If you discover atext files (the "Software") to be used in connection with the defect in the media during this warranty period, you may obtainbook. SYBEX hereby grants to you a license to use the Software, a replacement of identical format at no charge by sending thesubject to the terms that follow. Your purchase, acceptance, or defective media, postage prepaid, with proof of purchase to:use of the Software will constitute your acceptance of suchterms. SYBEX Inc.The Software compilation is the property of SYBEX unless Customer Service Departmentotherwise indicated and is protected by copyright to SYBEX or 1151 Marina Village Parkwayother copyright owner(s) as indicated in the media files (the Alameda, CA 94501"Owner(s)"). You are hereby granted a single-user license to use (510) 523-8233the Software for your personal, noncommercial use only. You Fax: (510) 523-2373may not reproduce, sell, distribute, publish, circulate, or com- e-mail: info@sybex.commercially exploit the Software, or any portion thereof, without WEB: HTTP://WWW.SYBEX.COMthe written consent of SYBEX and the specific copyrightowner(s) of any component software included on this media. After the 90-day period, you can obtain replacement media ofIn the event that the Software or components include specific identical format by sending us the defective disk, proof of pur-license requirements or end-user agreements, statements of chase, and a check or money order for $10, payable to SYBEX.condition, disclaimers, limitations or warranties ("End-UserLicense"), those End-User Licenses supersede the terms and con- Disclaimerditions herein as to that particular Software component. Your SYBEX makes no warranty or representation, either expressedpurchase, acceptance, or use of the Software will constitute your or implied, with respect to the Software or its contents, quality,acceptance of such End-User Licenses. performance, merchantability, or fitness for a particular pur-By purchase, use or acceptance of the Software you further agree pose. In no event will SYBEX, its distributors, or dealers be liableto comply with all export laws and regulations of the United to you or any other party for direct, indirect, special, incidental,States as such laws and regulations may exist from time to time. consequential, or other damages arising out of the use of or inability to use the Software or its contents even if advised of theReusable Code in This Book possibility of such damage. In the event that the SoftwareThe authors created reusable code in this publication expressly includes an online update feature, SYBEX further disclaims anyfor reuse for readers. Sybex grants readers permission to reuse obligation to provide this feature for any specific duration otherfor any purpose the code found in this publication or its accom- than the initial posting.panying CD-ROM so long as all three authors are attributed in The exclusion of implied warranties is not permitted by someany application containing the reusable code, and the code itself states. Therefore, the above exclusion may not apply to never sold or commercially exploited as a stand-alone product. This warranty provides you with specific legal rights; there may be other rights that you may have that vary from state to state.Software Support The pricing of the book with the Software by SYBEX reflects theComponents of the supplemental Software and any offers associ- allocation of risk and limitations on liability contained in thisated with them may be supported by the specific Owner(s) of that agreement of Terms and Conditions.material but they are not supported by SYBEX. Information regard-ing any available support may be obtained from the Owner(s) using Shareware Distributionthe information provided in the appropriate files or listed This Software may contain various programs that are distributedelsewhere on the media. as shareware. Copyright laws apply to both shareware and ordi-Should the manufacturer(s) or other Owner(s) cease to offer sup- nary commercial software, and the copyright Owner(s) retainsport or decline to honor any offer, SYBEX bears no responsibil- all rights. If you try a shareware program and continue using it,ity. This notice concerning support for the Software is provided you are expected to register it. Individual programs differ onfor your information only. SYBEX is not the agent or principal details of trial periods, registration, and payment. Please observeof the Owner(s), and SYBEX is in no way responsible for pro- the requirements stated in appropriate files.viding any support for the Software, nor is it liable or responsiblefor any support provided, or not provided, by the Owner(s). Copy Protection The Software in whole or in part may or may not be copy-pro-Warranty tected or encrypted. However, in all cases, reselling or redistrib-SYBEX warrants the enclosed media to be free of physical defects uting these files without authorization is expressly forbiddenfor a period of ninety (90) days after purchase. The Software is not except as specifically provided for by the Owner(s) therein. Copyright ©2000 SYBEX , Inc., Alameda, CA
  5. 5. This book is dedicated to all the Cisco Academy instructors, the unsung heroesof the training industry. They work very hard, are extremely dedicated, andmake little money teaching. Their reward is the students progressing, learning,and becoming all they can be. I salute you. Copyright ©2000 SYBEX , Inc., Alameda, CA
  6. 6. Acknowledgments Creating the Acknowledgments is the most difficult part of the book- writing process. Without the help and support of many different individuals, this book, or any other book for that matter, would never be written. So, how can someone actually take a few paragraphs and thank and acknowl- edge everyone involved? I will give it a try anyway. The person I want to thank and acknowledge first is Linda Lee. She is an incredible developmental editor and really helped me develop this book’s outline. I am very happy that she was involved in the process. She worked hard on this book, and the reader now gets to reap the rewards of her labor. Neil Edde is always a shoo-in for appearing in the acknowledgments of all my books. Without Neil, I would not have written the first CCNA book, or even my first Sybex book. He was my first developmental editor, and Linda needs to thank him for working out most of my kinks before he pushed me over to her. Susan Berge and Lisa Duran did a great job of keeping up with the sched- ule and worked very hard with me to get this book shipped on time. For that, I thank them. Kudos to Patrick Ramseier and Eric Gunnett, who did a fab- ulous job of reviewing each chapter for technical accuracy. Thanks also to Sally Engelfried, Marilyn Smith, and Rebecca Rider for assisting with the editing of the chapters, and to Molly Glover, Jennifer Campbell, Laurie O’Connell, and Camera Obscura for proofreading the book. In addition, Maureen Forys deserves a thank you for putting the finishing touches on the book. And I don’t want to forget Tony Jonick. He is the artist who had to put up with my changing the figures in this book over and over again. He is very patient and does a fantastic job. Copyright ©2000 SYBEX , Inc., Alameda, CA
  7. 7. Introduction Welcome to the exciting world of Cisco certification! You have picked up this book because you want something better; namely, a better job with more satisfaction. Rest assured that you have made a good decision. Cisco certification can help you get your first networking job, or more money and a promotion if you are already in the field. Cisco certification can also improve your understanding of the internet- working of more than just Cisco products: You will develop a complete understanding of networking and how different network topologies work together to form a network. This is beneficial to every networking job and is the reason Cisco certification is in such high demand, even at companies with few Cisco devices. Cisco is the king of routing and switching, the Microsoft of the internet- working world. The new Cisco certifications reach beyond the popular certifications, such as the MCSE and CNE, to provide you with an indispens- able factor in understanding today’s network—insight into the Cisco world of internetworking. By deciding that you want to become Cisco certified, you are saying that you want to be the best—the best at routing and the best at switching. This book can lead you in that direction. Cisco—A Brief History A lot of readers may already be familiar with Cisco and what they do. How- ever, those of you who are new to the field, just coming in fresh from your MCSE, and those of you who maybe have 10 or more years in the field but wish to brush up on the new technology may appreciate a little background on Cisco. In the early 1980s, Len and Sandy Bosack, a married couple who worked in different computer departments at Stanford University, were having trouble getting their individual systems to communicate (like many married people). So in their living room they created a gateway server that made it easier for their disparate computers in two different departments to commu- nicate using the IP protocol. In 1984, they founded cisco Systems (notice the small c) with a small commercial gateway server product that changed net- working forever. Some people think the name was intended to be San Fran- cisco Systems but the paper got ripped on the way to the incorporation Copyright ©2000 SYBEX , Inc., Alameda, CA
  8. 8. xxiv Introduction lawyers—who knows? In 1992, the company name was changed to Cisco Systems, Inc. The first product the company marketed was called the Advanced Gate- way Server (AGS). Then came the Mid-Range Gateway Server (MGS), the Compact Gateway Server (CGS), the Integrated Gateway Server (IGS), and the AGS+. Cisco calls these “the old alphabet soup products.” In 1993, Cisco came out with the amazing 4000 router and then created the even more amazing 7000, 2000, and 3000 series routers. These are still around and evolving (almost daily, it seems). Cisco has since become an unrivaled worldwide leader in networking for the Internet. Its networking solutions can easily connect users who work from diverse devices on disparate networks. Cisco products make it simple for people to access and transfer information without regard to differences in time, place, or platform. In the big picture, Cisco provides end-to-end networking solutions that customers can use to build an efficient, unified information infrastructure of their own or to connect to someone else’s. This is an important piece in the Internet/networking–industry puzzle because a common architecture that delivers consistent network services to all users is now a functional imperative. Because Cisco Systems offers such a broad range of networking and Internet services and capabilities, users needing regular access to their local network or the Internet can do so unhindered, making Cisco’s wares indispensable. Cisco answers this need with a wide range of hardware products that form information networks using the Cisco Internetwork Operating System (IOS) software. This software provides network services, paving the way for networked technical support and professional services to maintain and opti- mize all network operations. Along with the Cisco IOS, one of the services Cisco created to help sup- port the vast amount of hardware it has engineered is the Cisco Certified Internetwork Expert (CCIE) program, which was designed specifically to equip people to effectively manage the vast quantity of installed Cisco net- works. The business plan is simple: If you want to sell more Cisco equipment and have more Cisco networks installed, ensure that the networks you install run properly. However, having a fabulous product line isn’t all it takes to guarantee the huge success that Cisco enjoys—lots of companies with great products are now defunct. If you have complicated products designed to solve compli- cated problems, you need knowledgeable people who are fully capable of Copyright ©2000 SYBEX , Inc., Alameda, CA
  9. 9. Introduction xxv installing, managing, and troubleshooting them. That part isn’t easy, so Cisco began the CCIE program to equip people to support these complicated networks. This program, known colloquially as the Doctorate of Network- ing, has also been very successful, primarily due to its extreme difficulty. Cisco continuously monitors the program, changing it as it sees fit, to make sure that it remains pertinent and accurately reflects the demands of today’s internetworking business environments. Building upon the highly successful CCIE program, Cisco Career Certifi- cations permit you to become certified at various levels of technical profi- ciency, spanning the disciplines of network design and support. So, whether you’re beginning a career, changing careers, securing your present position, or seeking to refine and promote your position, this is the book for you!Cisco’s Network Support Certifications Cisco has created new certifications that will help you get the coveted CCIE, as well as aid prospective employers in measuring skill levels. Before these new certifications, you took only one test and were then faced with the lab, which made it difficult to succeed. With these new certifications, which add a better approach to preparing for that almighty lab, Cisco has opened doors that few were allowed through before. So, what are these new certifications and how do they help you get your CCIE? Cisco Certified Network Associate (CCNA) 2 The CCNA certification is the first in the new line of Cisco certifications, and it is a precursor to all current Cisco certifications. With the new certification programs, Cisco has created a type of stepping-stone approach to CCIE cer- tification. Now, you can become a Cisco Certified Network Associate for the meager cost of this book, plus $100 for the test. And you don’t have to stop there—you can choose to continue with your studies and achieve a higher certification, called the Cisco Certified Network Professional (CCNP). Someone with a CCNP has all the skills and knowledge he or she needs to attempt the CCIE lab. However, because no textbook can take the place of practical experience, we’ll discuss what else you need to be ready for the CCIE lab shortly. Copyright ©2000 SYBEX , Inc., Alameda, CA
  10. 10. xxvi Introduction Why Become a CCNA? Cisco, not unlike Microsoft or Novell, has created the certification process to give administrators a set of skills and to equip prospective employers with a way to measure skills or match certain criteria. Becoming a CCNA can be the initial step of a successful journey toward a new, highly rewarding, and sustainable career. The CCNA program was created to provide a solid introduction not only to the Cisco Internetwork Operating System (IOS) and Cisco hardware, but also to internetworking in general, making it helpful to you in areas that are not exclusively Cisco’s. At this point in the certification process, it’s not unrealistic to imagine that future network managers—even those without Cisco equipment—could easily require Cisco certifications for their job applicants. If you make it through the CCNA and are still interested in Cisco and internetworking, you’re headed down a path to certain success. What Skills Do You Need to Become a CCNA? To meet the CCNA certification skill level, you must be able to understand or do the following: Install, configure, and operate simple-routed LAN, routed WAN, and switched LAN and LANE networks. Understand and be able to configure IP, IGRP, IPX, serial, AppleTalk, Frame Relay, IP RIP, VLANs, IPX RIP, Ethernet, and access lists. Install and/or configure a network. Optimize WAN through Internet-access solutions that reduce band- width and WAN costs, using features such as filtering with access lists, bandwidth on demand (BOD), and dial-on-demand routing (DDR). Provide remote access by integrating dial-up connectivity with tradi- tional, remote LAN-to-LAN access, as well as supporting the higher levels of performance required for new applications such as Internet commerce, multimedia, etc. How Do You Become a CCNA? The first step to becoming a CCNA is to pass one little test and—poof!— you’re a CCNA. (Don’t you wish it were that easy?) True, it’s just one test, Copyright ©2000 SYBEX , Inc., Alameda, CA
  11. 11. Introduction xxvii but you still have to possess enough knowledge to understand (and read between the lines—trust me) what the test writers are saying. I can’t stress this enough—it’s critical that you have some hands-on expe- rience with Cisco routers. If you can get ahold of some 2500 routers, you’re set. But if you can’t, we’ve worked hard to provide hundreds of configura- tion examples throughout this book to help network administrators (or peo- ple who want to become network administrators) learn what they need to know to pass the CCNA exam. One way to get the hands-on router experience you’ll need in the real world is to attend one of the seminars offered by Globalnet Training Solu- tions, Inc., which is owned and run by me. The seminars are six days long and will teach you everything you need to become a CCNA and even a CCNP. Each student gets hands-on experience by configuring at least two routers and a switch. See for more information. In addition, Cyberstate University provides hands-on Cisco router courses over the Internet using the Sybex Cisco Certification series books. Go to for more information. And Keystone Learn- ing Systems ( offers the popular Cisco video certification series featuring me. If you are new to networking, you should take a look at CCNA JumpStart by Patrick Ciccarelli and Christina Faulkner (Sybex, 1999). This book will give you the background necessary before jumping into more advanced net- working with Cisco routers. Check out this book’s CD for a demo of the Sybex CCNA Virtual Lab e- trainer, which can give you hands-on experience working with both routers and switches. You can also check out for another router simulator. In addition to this book, there are other useful ways to supplement your stud- ies for the CCNA exam. CiscoTests ( offers an online study guide with sample questions and information about the most current release of the CCNA, CCNP, and CCIE exams. For the best practice Cisco exam questions on the market, try ©2000 SYBEX , Inc., Alameda, CA
  12. 12. xxviii Introduction Cisco Certified Network Professional (CCNP) Cisco Certified Network Professional (CCNP), Cisco’s new certification, has opened up many opportunities for those individuals wishing to become Cisco-certified but lacking the training, the expertise, or the bucks to pass the notorious and often failed two-day Cisco torture lab. The new Cisco certifi- cations will truly provide exciting new opportunities for the CNE and MCSE who are unsure of how to advance to a higher level. So, you’re thinking, “Great, what do I do after passing the CCNA exam?” Well, if you want to become a CCIE in Routing and Switching (the most pop- ular certification), understand that there’s more than one path to that much- coveted CCIE certification. The first way is to continue studying and become a Cisco Certified Network Professional (CCNP), which means four more tests, in addition to the CCNA certification. The CCNP program will prepare you to understand and comprehensively tackle the internetworking issues of today and beyond—and it is not limited to the Cisco world. You will undergo an immense metamorphosis, vastly increasing your knowledge and skills through the process of obtaining these certifications. While you don’t need to be a CCNP or even a CCNA to take the CCIE lab, it’s extremely helpful if you already have these certifications. What Skills Do You Need to Become a CCNP? Cisco demands a certain level of proficiency for its CCNP certification. In addition to mastering the skills required for the CCNA, you should have the following skills for the CCNP: Installing, configuring, operating, and troubleshooting complex routed LAN, routed WAN, and switched LAN networks, along with dial-access services Understanding complex networks, such as IP, IGRP, IPX, async rout- ing, AppleTalk, extended access lists, IP RIP, route redistribution, IPX RIP, route summarization, OSPF, VLSM, BGP, serial, IGRP, Frame Relay, ISDN, ISL, X.25, DDR, PSTN, PPP, VLANs, Ethernet, ATM LANE–emulation, access lists, 802.10, FDDI, and transparent and translational bridging Copyright ©2000 SYBEX , Inc., Alameda, CA
  13. 13. Introduction xxix To meet the CCNP requirements, you must be able to perform the following: Install and/or configure a network to increase bandwidth, quicken network response times, and improve reliability and quality of service. Maximize performance through campus LANs, routed WANs, and remote access. Improve network security. Create a global intranet. Provide access security to campus switches and routers. Provide increased switching and routing bandwidth—end-to-end resiliency services. Provide custom queuing and routed priority services. How Do You Become a CCNP? After becoming a CCNA, the four exams you must take to get your CCNP are as follows: Exam 640-503: Routing This exam continues to build on the funda- mentals learned in the CCNA course. It focuses on large multiprotocol internetworks and how to manage them with access lists, queuing, tun- neling, route distribution, route maps, BGP, EIGRP, OSPF, and route summarization. Exam 640-504: Switching This exam tests your knowledge of the 1900 and 5000 series of Catalyst switches. The CCNP: Switching Study Guide (Sybex, summer 2000) covers all the objectives you need to understand to pass the Switching exam. Exam 640-506: Support This tests you on the Cisco troubleshooting skills needed for Ethernet and Token Ring LANs, IP, IPX, and AppleTalk networks, as well as ISDN, PPP, and Frame Relay networks. Exam 640-505: Remote Access This exam tests your knowledge of installing, configuring, monitoring, and troubleshooting Cisco ISDN and dial-up access products. You must understand PPP, ISDN, Frame Relay, and authentication. The CCNP: Remote Access Study Guide (Sybex, summer 2000) covers all the exam objectives.Copyright ©2000 SYBEX , Inc., Alameda, CA
  14. 14. xxx Introduction If you hate tests, you can take fewer of them by signing up for the CCNA exam and the Support exam and then taking just one more long exam called the Foundation R/S exam (640-509). Doing this also gives you your CCNP—but beware; it’s a really long test that fuses all the material listed previously into one exam. Good luck! However, by taking this exam, you get three tests for the price of two, which saves you $100 (if you pass). Some people think it’s easier to take the Foundation R/S exam because you can leverage the areas that you would score higher in against the areas in which you wouldn’t. Remember that test objectives and tests can change at any time without notice. Always check the Cisco Web site for the most up-to-date information ( Cisco Certified Internetwork Expert (CCIE) You’ve become a CCNP, and now you fix your sights on getting your Cisco Certified Internetwork Expert CCIE in Routing and Switching—what do you do next? Cisco recommends that before you take the lab, you take test 640-025: Cisco Internetwork Design (CID) and the Cisco-authorized course called Installing and Maintaining Cisco Routers (IMCR). By the way, no Prometric test for IMCR exists at the time of this writing, and Cisco recom- mends a minimum of two years of on-the-job experience before taking the CCIE lab. After jumping those hurdles, you then have to pass the CCIE-R/S Exam Qualification (exam 350-001) before taking the actual lab. How Do You Become a CCIE? To become a CCIE, Cisco recommends you do the following: 1. Attend all the recommended courses at an authorized Cisco training center and pony up around $15,000–$20,000, depending on your cor- porate discount. 2. Pass the Drake/Prometric exam ($200 per exam—so hopefully, you’ll pass it the first time). 3. Pass the two-day, hands-on lab at Cisco. This costs $1,000 per lab, which many people fail two or more times. (Some never make it Copyright ©2000 SYBEX , Inc., Alameda, CA
  15. 15. Introduction xxxi through!) Also, because you can take the exam only in San Jose, Cal- ifornia; Research Triangle Park, North Carolina; Sydney, Australia; Halifax, Nova Scotia; Tokyo, Japan; or Brussels, Belgium, you might just need to add travel costs to that $1,000. Cisco has added new sites lately for the CCIE lab; it is best to check the Cisco Web site for the most current information. What Skills Do You Need to Become a CCIE? The CCIE Routing and Switching exam includes the advanced technical skills that are required to maintain optimum network performance and reliability, as well as advanced skills in supporting diverse networks that use disparate technologies. CCIEs just don’t have problems getting jobs; these experts are basically inundated with offers to work for six-figure salaries. But that’s because it isn’t easy to attain the level of capability that is mandatory for Cisco’s CCIE. For example, a CCIE has the following skills down pat: Installing, configuring, operating, and troubleshooting complex routed LAN, routed WAN, switched LAN, and ATM LANE networks, and dial-access services Diagnosing and resolving network faults Using packet/frame analysis and Cisco debugging tools Documenting and reporting the problem-solving processes used Having general LAN/WAN knowledge, including data encapsulation and layering; windowing and flow control, and their relation to delay; error detection and recovery; link-state, distance vector, and switching algorithms; management, monitoring, and fault isolation Having knowledge of a variety of corporate technologies—including major services provided by Desktop, WAN, and Internet groups—as well as the functions; addressing structures; and routing, switching, and bridging implications of each of their protocols Having knowledge of Cisco-specific technologies, including router/ switch platforms, architectures, and applications; communication servers; protocol translation and applications; configuration com- mands and system/network impact; and LAN/WAN interfaces, capa- bilities, and applications Designing, configuring, installing, and verifying voice-over-IP and voice-over-ATM networksCopyright ©2000 SYBEX , Inc., Alameda, CA
  16. 16. xxxii Introduction Cisco’s Network Design Certifications In addition to the network support certifications, Cisco has created another certification track for network designers. The two certifications within this track are the Cisco Certified Design Associate and Cisco Certified Design Professional certifications. If you’re reaching for the CCIE stars, we highly recommend the CCNP and CCDP certifications before attempting the lab (or attempting to advance your career). This certification will give you the knowledge to design routed LAN, routed WAN, and switched LAN and ATM LANE networks. Cisco Certified Design Associate (CCDA) To become a CCDA, you must pass the DCN (Designing Cisco Networks) exam (640-441). To pass this test, you must understand how to do the following: Design simple routed LAN, routed WAN, and switched LAN and ATM LANE networks. Use Network-layer addressing. Filter with access lists. Use and propagate VLAN. Size networks. The Sybex CCDA: Cisco Certified Design Associate Study Guide (1999) is the most cost-effective way to study for and pass your CCDA exam. Cisco Certified Design Professional (CCDP) If you’re already a CCNP and want to get your CCDP, you can simply take the CID 640-025 test. If you’re not yet a CCNP, however, you must take the CCDA, CCNA, Routing, Switching, Remote Access, and CID exams. CCDP certification skills include the following: Designing complex routed LAN, routed WAN, and switched LAN and ATM LANE networks Building upon the base level of the CCDA technical knowledge Copyright ©2000 SYBEX , Inc., Alameda, CA
  17. 17. Introduction xxxiii CCDPs must also demonstrate proficiency in the following: Network-layer addressing in a hierarchical environment Traffic management with access lists Hierarchical network design VLAN use and propagation Performance considerations: required hardware and software; switch- ing engines; memory, cost, and minimizationWhat Does This Book Cover? This book covers everything you need to know in order to become CCNA certified. However, taking the time to study and practice with routers or a router simulator is the real key to success. The information you will learn in this book, and need to know for the CCNA exam, is listed in the following bullet points: Chapter 1 introduces you to internetworking. You will learn the basics of the Open Systems Interconnection the way Cisco wants you to learn it. Also, the Cisco three-layer hierarchical model will be dis- cussed, along with how to choose Cisco equipment based on this model. Ethernet networking and standards are discussed in detail in this chapter as well. Chapter 2 gives you a background on layer-2 switching and how switches perform address learning and make forwarding and filtering decisions. Network loops and how to avoid them with the Spanning- Tree Protocol (STP) will be discussed, as well as the different LAN switch types used by Cisco switches. Chapter 3 provides you with the background necessary for success on the exam as well as in the real world by discussing TCP/IP. This in-depth chapter covers the very beginnings of the Internet Protocol stack and then goes all the way to IP addressing and subnetting. If you read this chapter carefully, you will be able to subnet a network in your head! Chapter 4 introduces you to the Cisco Internetwork Operating System (IOS). In this chapter you will learn how to turn on a router and Copyright ©2000 SYBEX , Inc., Alameda, CA
  18. 18. xxxiv Introduction configure the basics of the IOS, including setting passwords, banners, and more. IP configuration will be discussed and a hands-on lab will help you gain a firm grasp of the concepts taught in the chapter. Chapter 5 teaches you about IP routing. This is a fun chapter, because you will begin to build your network, add IP addresses, and route data between routers. You will also learn about static, default, and dynamic routing in this chapter. Written and hands-on labs will help you understand IP routing to the fullest. Chapter 6 covers Virtual LANs and how you can use them in your internetwork. This chapter also covers the nitty-gritty of VLANs and the different concepts and protocols used with VLANs. Written labs and review questions will reinforce the VLAN material. Chapter 7 provides you with the management skills needed to run a Cisco ISO network. Backing up and restoring the IOS, as well as router configuration, is covered, as are troubleshooting tools neces- sary to keep a network up and running. Chapter 8 introduces you to the wonderful world of Novell IPX. Since IPX is still around, Cisco thinks it is important to understand IPX routing. Actually, after IP routing, IPX is a breeze. Both written and hands-on labs, along with review questions, will give you the under- standing of IPX you need to pass the CCNA exam. Chapter 9 covers access lists, which are created on routers to filter the network. Both IP and IPX access lists are covered in detail. Written and hands-on labs, along with review questions, will help you study for the access-list portion of the CCNA exam. Chapter 10 concentrates on Cisco Wide Area Network protocols. This chapter covers HDLC, PPP, Frame Relay, and ISDN in depth. You must be proficient in all these protocols to be successful on the CCNA exam. Appendix A is a practice exam. If you think you are ready for the CCNA exam, see if you can get by my practice exam. A second prac- tice exam is located on the CD as well. Appendix B discusses configuring a Catalyst 1900 switch. The CCNA exam is mostly theory on layer-2 switching; however, reading the appendix, working through the written and hands-on labs, and Copyright ©2000 SYBEX , Inc., Alameda, CA
  19. 19. Introduction xxxv answering the review questions should prepare you well for the CCNA exam. Appendix C lists all the Cisco IOS commands used in this book. It is a great reference if you need to look up what a certain command does and is used for. The Glossary is a handy resource for Cisco terms. This is a great tool for understanding some of the more obscure terms used in this book.Where Do You Take the Exams? You may take the exams at any of the more than 800 Sylvan Prometric Authorized Testing Centers around the world. For the location of a testing center near you, call (800) 755-3926. Outside the United States and Canada, contact your local Sylvan Prometric Registration Center. To register for a Cisco Certified Network Professional exam: 1. Determine the number of the exam you want to take. (The CCNA exam number is 640-507.) 2. Register with the nearest Sylvan Prometric Registration Center. At this point, you will be asked to pay in advance for the exam. At the time of this writing, the exams are $100 each and must be taken within one year of payment. You can schedule exams up to six weeks in advance or as soon as one working day prior to the day you wish to take it. If something comes up and you need to cancel or reschedule your exam appointment, contact Sylvan Prometric at least 24 hours in advance. Same-day registration isn’t available for the Cisco tests. 3. When you schedule the exam, you’ll get instructions regarding all appointment and cancellation procedures, the ID requirements, and information about the testing-center location.Tips for Taking Your CCNA Exam The CCNA test contains about 70 questions to be completed in 90 minutes. You must schedule a test at least 24 hours in advance (unlike the Novell or Microsoft exams), and you aren’t allowed to take more than one Cisco exam per day. Copyright ©2000 SYBEX , Inc., Alameda, CA
  20. 20. xxxvi Introduction Many questions on the exam have answer choices that at first glance look identical—especially the syntax questions! Remember to read through the choices carefully because close doesn’t cut it. If you get commands in the wrong order or forget one measly character, you’ll get the question wrong. So, to practice, do the hands-on exercises at the end of the chapters over and over again until they feel natural to you. Unlike Microsoft or Novell tests, the exam has answer choices that are syntactically similar—though some syntax is dead wrong, it is usually just subtly wrong. Some other choices may be syntactically correct, but they’re shown in the wrong order. Cisco does split hairs, and they’re not at all averse to giving you classic trick questions. Here’s an example: access-list 101 deny ip any eq 23 denies Telnet access to all systems. This question looks correct because most people refer to the port number (23) and think, “Yes, that’s the port used for Telnet.” The catch is that you can’t filter IP on port numbers (only TCP and UDP). Also, never forget that the right answer is the Cisco answer. In many cases, more than one appropriate answer is presented, but the correct answer is the one that Cisco recommends. Here are some general tips for exam success: Arrive early at the exam center, so you can relax and review your study materials. Read the questions carefully. Don’t jump to conclusions. Make sure you’re clear about exactly what each question asks. When answering multiple-choice questions that you’re not sure about, use the process of elimination to get rid of the obviously incorrect answers first. Doing this greatly improves your odds if you need to make an educated guess. You can no longer move forward and backward through the Cisco exams, so double-check your answer before pressing Next since you can’t change your mind. After you complete an exam, you’ll get immediate, online notification of your pass or fail status, a printed Examination Score Report that indicates your pass or fail status, and your exam results by section. (The test admin- istrator will give you the printed score report.) Test scores are automatically forwarded to Cisco within five working days after you take the test, so you Copyright ©2000 SYBEX , Inc., Alameda, CA
  21. 21. Introduction xxxvii don’t need to send your score to them. If you pass the exam, you’ll receive confirmation from Cisco, typically within two to four weeks.How to Use This Book This book can provide a solid foundation for the serious effort of preparing for the Cisco Certified Network Associate (CCNA) exam. To best benefit from this book, use the following study method: 1. Take the assessment test immediately following this introduction. (The answers are at the end of the test.) Carefully read over the expla- nations for any question you get wrong and note which chapters the material comes from. This information should help you plan your study strategy. 2. Study each chapter carefully, making sure that you fully understand the information and the test topics listed at the beginning of each chapter. Pay extra-close attention to any chapter where you missed questions in the assessment test. 3. Complete all hands-on exercises in the chapter, referring to the chap- ter so that you understand the reason for each step you take. If you do not have Cisco equipment available, be sure to study the examples carefully. Also, check for a router simulator. 4. Answer the review questions related to that chapter. (The answers appear at the end of the chapter.) Note the questions that confuse you and study those sections of the book again. 5. Take the practice exam in Appendix A. The answers appear at the end of the exam. 6. Try your hand at the bonus practice exam that is included on the CD that comes with this book. The questions in this exam appear only on the CD. This will give you a complete overview of what you can expect to see on the real thing. 7. Remember to use the products on the CD included with this book. The electronic flashcards, the Boson Software utilities, and the EdgeTest exam preparation software have all been specifically chosen to help you study for and pass your exam. You can also study on the road with the CCNA Study Guide electronic book in PDF format. Copyright ©2000 SYBEX , Inc., Alameda, CA
  22. 22. xxxviii Introduction The electronic flashcards can be used on your Windows computer or on your Palm device. 8. Make sure you read the “Key Terms” and “Commands in This Chap- ter” lists at the end of the chapters. Appendix C is a copy of all com- mands used in the book, including explanations for each command. To learn all the material covered in this book, you’ll have to apply your- self regularly and with discipline. Try to set aside the same time period every day to study, and select a comfortable and quiet place to do so. If you work hard, you will be surprised at how quickly you learn this material. All the best! What’s on the CD? We worked hard to provide some really great tools to help you with your cer- tification process. All of the following tools should be loaded on your work- station when studying for the test. The EdgeTest Test Preparation Software The test preparation software, provided by EdgeTek Learning Systems, pre- pares you to pass the CCNA exam. In this test engine you will find all the questions from the book, plus an additional bonus practice exam that appears exclusively on the CD. You can take the assessment test, test your- self by chapter, take the practice exam that appears in the book or on the CD, or take a randomly generated exam comprising all the questions. To find more test-simulation software for all Cisco and NT exams, look for the exam link on and Electronic Flashcards for PC and Palm Devices To prepare for the exam, you can read this book, study the review questions at the end of each chapter, and work through the practice exams included in the book and on the CD. But wait, there’s more! Test yourself with the flashcards included on the CD. If you can get through these difficult Copyright ©2000 SYBEX , Inc., Alameda, CA
  23. 23. Introduction xxxix questions and understand the answers, you’ll know you’re ready for the CCNA exam. The flashcards include over 200 questions specifically written to hit you hard and make sure you are ready for the exam. Between the review ques- tions, practice exams, and flashcards, you’ll be more than prepared for the exam. CCNA Study Guide in PDF Sybex offers the CCNA Study Guide in PDF format on the CD so you can read the book on your PC or laptop. This will be helpful to readers who travel and don’t want to carry a book, as well as to readers who prefer to read from their computer. (Acrobat Reader 4 is also included on the CD.) Dictionary of Networking in PDF As a bonus, you get a second complete book—the Sybex Dictionary of Net- working, by Peter Dyson—on the CD included with this book. Like the elec- tronic version of the CCNA Study Guide, the fully searchable Dictionary of Networking is in PDF for ease of use. You will also find Adobe Acrobat 4 with Search on the CD to access the PDF book. This dictionary will help you understand terms found in this book or networking terms found in any book for that matter. Boson Software Utilities is an impressive company: They provide many free services to help you, the student. has the best Cisco exam preparation ques- tions on the market at a very nice price. On this book’s CD, they have pro- vided the following: Practice exam IP Subnetter eeSuperPing System-Logging Wildcard Mask CheckerCopyright ©2000 SYBEX , Inc., Alameda, CA
  24. 24. xl Introduction CCNA Virtual Lab AVI Demo Files The CCNA Virtual Lab e-trainer provides a router and switch simulator to help you gain hands-on experience without having to buy expensive Cisco gear. The AVI demo files on the CD will help you gain an understanding of the product features and the labs that the routers and switches can perform. Read more about the CCNA Virtual Lab e-trainer at http://www.sybex .com/cgi-bin/ You can upgrade this product at How to Contact the Author You can reach Todd Lammle through Globalnet System Solutions, Inc. (—his training and systems integration company in Colo- rado—or e-mail him at Copyright ©2000 SYBEX , Inc., Alameda, CA
  25. 25. Assessment Questions xliAssessment Questions 1. Where would a router boot from if a configuration register was set to 0x0101? A. Flash B. ROM C. Boot ROM D. NVRAM 2. Which of the following is a valid SAP filter 1010 placed on Ethernet 0? A. ip access-group 1010 in B. ip access-group 1010 out C. ipx access-group 1010 in D. ipx input-sap-filter 1010 E. ipx input-sap-filter 1010 in 3. What is a TE2 device used for in an ISDN connection? A. Connecting an NT2 device to a U reference point B. Connecting an S/T interface to a U reference point C. Connecting a non-ISDN terminal to ISDN through a TA D. Connecting to ISDN through a four-wire, twisted-pair digital link 4. What is the correct command to set the router identification to the name Atlanta, which an administrator would see when connecting with Telnet or through the console? A. Description Atlanta Router B. Banner Motd $ C. Hostname Atlanta D. Host name Atlanta E. Set prompt Atlanta Copyright ©2000 SYBEX , Inc., Alameda, CA
  26. 26. xlii Assessment Questions 5. PDUs at the Data Link layer are named what? A. Frames B. Packets C. Datagrams D. Transports E. Segments F. Bits 6. Which of the following is the valid host range for the IP address A.–190 B.–191 C.–190 D.–192 7. What are the access list numbers used for IP standard access lists? A. 1–10 B. 1–99 C. 100–199 D. 1000–1999 8. If you type show interface serial 0 and receive the following response, what could the problem be? RouterA#sh int s0 Serial0 is up, line protocol is down A. The keepalives could be set wrong between the point-to-point links. B. No cable is attached to the interface. C. The administrator needs to issue a no shutdown request to the interface. D. The interface is defective. Copyright ©2000 SYBEX , Inc., Alameda, CA
  27. 27. Assessment Questions xliii 9. Which of the following commands will show you the IPX address of an interface? (Choose all that apply.) A. show ipx address int e0 B. show protocol C. show ipx protocol D. show ipx interface 10. How do you create a default route? A. By using all 1s in place of the network and mask B. By defining a static route and using all 0s in place of the network and mask C. By using 255 in place of the network and mask D. Login <name, password> 11. What is a trunked link? A. A link that is only part of one VLAN and is referred to as the native VLAN of the port B. A link that can carry multiple VLANs C. A switch port connected to the Internet D. Data and voice capability on the same interface 12. Which protocol is used to look up an IP address from a known Ether- net address? A. IP B. ARP C. RARP D. TCPCopyright ©2000 SYBEX , Inc., Alameda, CA
  28. 28. xliv Assessment Questions 13. What is the broadcast address of the subnet address A. B. C. D. 14. What is the valid host range that the host ID is a part of? A.–63 B.–63 C.–62 D.–61 15. What does a switch do with a multicast frame received on an interface? A. Forwards the switch to the first available link B. Drops the frame C. Floods the network with the frame looking for the device D. Sends back a message to the originating station asking for a name resolution 16. Which command would you use to see the IPX RIP packets being sent and received on an interface? A. show ip rip B. sh ipx int C. debug ipx routing activity D. debug ipx interface Copyright ©2000 SYBEX , Inc., Alameda, CA
  29. 29. Assessment Questions xlv 17. What is the subnet address of the IP address A. B. C. D. 18. What is an access link? A. A link that is only part of one VLAN and is referred to as the native VLAN of the port B. A link that can carry multiple VLANs C. A switch port connected to the Internet D. Data and voice capability on the same interface 19. Which of the following is true? (Choose all that apply.) A. PPP can be used with Token Ring. B. PPP can be used with synchronous serial links. C. PPP can be used with asynchronous serial links. D. PPP is proprietary to each vendor’s equipment. 20. What command can you use to back up the Cisco router configuration to a TFTP host? A. copy run tftp B. copy flash tftp C. copy nvram startup D. copy tftp flashCopyright ©2000 SYBEX , Inc., Alameda, CA
  30. 30. xlvi Assessment Questions 21. Which of the following are provided by the show cdp entry * com- mand? (Choose all that apply.) A. IP address of the neighbor router B. Protocol information C. Platform D. Capability E. Time F. Port ID G. Holdtime H. The same information as show version I. Neighbor device ID J. Local interface K. Speed of the link 22. Which of the following would you not implement at the distribution layer? A. Access lists B. Packet filtering C. Queuing D. Breakup of collisions domains E. Address translation F. Firewalls G. Creating of broadcast domains Copyright ©2000 SYBEX , Inc., Alameda, CA
  31. 31. Assessment Questions xlvii 23. Which LAN switch methods have a fixed latency time? (Choose all that apply.) A. Cut-through B. Store and forward C. FragmentCheck D. FragmentFree 24. If you were designing a network and needed to break up collision domains, at which Cisco layer would you provide this function? A. Physical B. Access C. Core D. Network E. Distribution F. Data Link 25. If you wanted to find out all the commands that start with “cl” from a certain prompt, what would you type at that particular prompt? A. Show commands cl B. Cl ? C. Cl? D. Cl ? more 26. What does a VLAN do? A. Breaks up collision domains B. Breaks up routing domains C. Breaks up broadcast domains D. Provides fragmentation segmentationCopyright ©2000 SYBEX , Inc., Alameda, CA
  32. 32. xlviii Assessment Questions 27. Which of the following will you find in a routing table? (Choose all that apply.) A. Network address B. Routing metric C. Exit interface for packets D. Entering interface 28. Which command can you use to see which devices have telnetted into your router? A. show vty line B. show vers C. show users D. show connections 29. What does an administrative distance of 0 mean? A. 0 is the default administrative distance for dynamic routing. B. 0 is the default administrative distance for directly connected routes. C. There is no routing allowed on this router. D. There are 0 hops to the next destination. 30. Which of the following is a valid IP extended access list? A. access-list 110 permit ip any host eq ftp B. access-list 10 permit tcp ip any any eq 21 C. access-list 99 permit udp any host eq ip D. access-list 199 permit tcp any eq 21 Copyright ©2000 SYBEX , Inc., Alameda, CA
  33. 33. Assessment Questions xlix 31. What is true regarding the blocking state of an STP switch port? (Choose all that apply.) A. Blocking ports do not forward any frames. B. Blocking ports listen for BPDUs. C. Blocking ports forward all frames. D. Blocking ports do not listen for BPDUs. 32. What is the default LAN switch type for the 1900 switch? A. FastForward B. Cut-through C. LAN switch type 1 D. FragmentFree E. Store and forward 33. Which of the following is true about the enable passwords? (Choose all that apply.) A. The enable password is encrypted by default. B. The enable secret is encrypted by default. C. The enable-encrypted password should be set first. D. The enable password supersedes the enable secret. E. The enable secret password supersedes the enable password. F. The enable-encrypted password supersedes all other passwords. 34. What is the default administrative distance of RIP? A. 1 B. 100 C. 120 D. 150Copyright ©2000 SYBEX , Inc., Alameda, CA
  34. 34. l Assessment Questions 35. If you are typing commands and receive the following message, what is wrong and how do you fix it? (Choose all that apply.) Router#clock set 10:30:10 % Incomplete command. A. The IOS doesn’t support a clock on this router. B. The command string is not done. C. Press the up arrow key and type a question mark. D. Press the down arrow key and the Tab key. E. Erase what you typed and reboot the router. 36. In the following command, what does the 175 mean? Ip route 175 A. It defines the next hop. B. It defines the administrative distance. C. It means that the update is broadcast. D. Nothing, it is an invalid command. 37. What does a router do with a received packet that is destined for an unknown network? A. Forwards the packet B. Drops the packet C. Holds the packet till the next route update D. Sends a broadcast for the unknown network 38. Which part is the network and which part is the node of the address 7c8.0001.00c8.1234? A. network: 7c8.0001, node: 00c8.1234 B. network: 7c8, node: 0001.00c8.1234 C. network: 0001.00c8.1234, node: 7c8 D. network: 7c8.0001.00c8, node: 1234 Copyright ©2000 SYBEX , Inc., Alameda, CA
  35. 35. Assessment Questions li 39. What are the two types of PDUs used at the Network layer? A. Data B. Route C. Static D. Dynamic E. Core F. Segments 40. What type of Cisco encapsulation is used for frame tagging across trunked links? A. Virtual Trunk Protocol (VTP) B. 802.1q C. ISL D. VLANs 41. What does IPX RIP use to find the best path to a remote network? (Choose all that apply.) A. Bandwidth of a link B. Hop count C. Reliability of a link D. Amount of delay, counted in 1/18 of a second 42. What are the access list numbers for extended access lists? A. 1–10 B. 1–99 C. 100–199 D. 1000–1999Copyright ©2000 SYBEX , Inc., Alameda, CA
  36. 36. lii Assessment Questions 43. What does the following command mean? Access-list 110 permit ip any A. It is a standard IP access list that permits network only. B. It is an extended IP access list that permits network only. C. It is an extended list that permits any host or network. D. It is invalid. 44. What is a static VLAN? A. A VLAN that cannot be renamed or removed B. A VLAN created by the administrator C. Ports on the switch assigned to a VLAN by an administrator D. Ports on the switch assigned to a VLAN by a VTP server 45. Which of the following is true regarding the isdn switch-type command? A. It can be configured only in global configuration mode. B. It can be configured only from interface configuration. C. It can be configured from either global or interface configura- tion mode. D. It can be used only when you have a TA. 46. If your Frame Relay network is congested, what mechanism is used to tell the source device to slow down? A. HDLC B. DLCI C. FECN D. BECN Copyright ©2000 SYBEX , Inc., Alameda, CA
  37. 37. Assessment Questions liii 47. Which of the following is a method used by Frame Relay for address- ing PVCs to IP addresses? A. ARP B. LMI C. SLARP D. DLCI 48. What are the two ways to add multiple encapsulations on an Ethernet IPX LAN? A. Multiple frame types B. Secondaries C. Subinterfaces D. Virtual secondaries 49. What is the typical time a switch port will go from blocking to for- warding state? A. 5 seconds B. 50 seconds C. 10 seconds D. 100 seconds 50. How do you telnet from a 1900 switch CLI? A. telnet Atlanta. B. telnet C. ping D. You cannot do this on a 1900 CLI.Copyright ©2000 SYBEX , Inc., Alameda, CA
  38. 38. liv Assessment Questions 51. What command will delete the automatically entered MAC addresses in the MAC filter table? A. (config)#delete nvram B. #delete nvram C. (config)#clear mac-address-table dynamic D. #clear mac-address-table dynamic 52. If you want to completely clear all configurations on a 1900 switch, what commands must you type in? (Choose all that apply.) A. Clear config B. Delete nvram C. Delete vtp D. Delete start E. Erase startup-config F. Just reboot the switch. 53. If you wanted to view the trunk status on port 27 of a 1900 switch, which command would you use? A. Show port 27 B. Show trunk C. Show trunk B D. Show trunk f0/27 E. Show trunk e0/27 54. What would you type at a 1900 console prompt to see the transmit and receive statistics of VTP? A. Show vtp stat B. Show stat C. Sh vtp domain D. Sh int e0/9 Copyright ©2000 SYBEX , Inc., Alameda, CA
  39. 39. Answers to the Assessment Questions lvAnswers to the Assessment Questions 1. B. The configuration register is used to tell the router how to load the IOS and configuration. The value 0x0101 tells the router to boot from ROM. See Chapter 7 for more information about configuration registers. 2. D. To place a SAP filter on an interface, use the command ipx input- sap-filter 1010 or ipx output-sap-filter 1010. See Chapter 9 for more information on IPX SAP filters. 3. D. This is a hard question. The TE2 is a device that does not under- stand ISDN standards and uses a four-wire connection. The TE2 must connect into a terminal adapter (TA) and then into an NT1 device to be converted to a two-wire network. See Chapter 10 for more infor- mation on ISDN. 4. C. The command hostname (one word) is used to set the name of the router. For more information on how to set the hostname of a router, see Chapter 4. 5. A. Protocol Data Units are used to describe the function of the headers used at each layer of the OSI model. At the Data Link layer, framing is used to encapsulate the data packet with control information for transmission on a local network. For more information on PDUs, see Chapter 1. 6. A. Start by using 256, the subnet mask, which is 256–192=64. The first subnet is 64. The next subnet would be 128. This host is in the 128 subnet, the broadcast address is 191, and the valid host range is 129 through 190. See Chapter 3 for more information on IP addressing. 7. B. Standard IP access lists use the numbers 1–99. See Chapter 9 for more information about access lists. 8. A. If you see the line is up, but the protocol is down, you are having a clocking (keepalive) or framing issue. Check the keepalives on both ends to make sure they match; the clock rate is set, if needed; and the encapsulation type is the same on both ends. For more information on interface statistics, see Chapter 4. Copyright ©2000 SYBEX , Inc., Alameda, CA
  40. 40. lvi Answers to the Assessment Questions 9. B, D. The commands show protocol and show ipx interface will show you the IPX addresses of an interface. See Chapter 8 for more information on IPX networking. 10. B. Default routes are created by using all 0s in place of the network and mask IDs. See Chapter 5 for more information on IP routing. 11. B. Trunked links carry multiple VLANs across the same link. For more information on VLANs, please see Chapter 6. 12. C. The protocol at the Network layer that finds an IP address from a known Ethernet address is Reverse ARP (RARP). See Chapter 3 for more information on IP protocols. 13. C. Start by using 256, the subnet mask, which is 256–25=4. The first subnet is 4. The next subnet would be 8, then 12, 16, 20, and 24. The broadcast address is 23, and the valid host range is 21 and 22. See Chapter 3 for more IP addressing information. 14. C. Start by using 256, the subnet mask, which is 256–224=32. The first subnet is 10.32. The next subnet would be 10.64. This host is in the 10.32 subnet, the broadcast address is 10.63, and the valid host range is 10.33 through 10.62. See Chapter 3 for more IP addressing information. 15. C. The switch will flood the network with the frame looking for the device. For more information on LAN switching, see Chapter 2. 16. B. The command show ipx interface will show you the IPX RIP and SAP information being sent and received on an individual inter- face. See Chapter 8 for more information on IPX. 17. B. Start by using 256, the subnet mask, which is 256–248=8. The first subnet is 8. The next subnet would be 16, then 24, and then 32. This host is in the 24 subnet, the broadcast address is 31, and the valid host range is 25 through 31. See Chapter 3 for more information on IP addressing. 18. A. Access links connect hosts to a switch and are part of only one VLAN. For more information on VLANs, please see Chapter 6. Copyright ©2000 SYBEX , Inc., Alameda, CA
  41. 41. Answers to the Assessment Questions lvii 19. B, C. PPP is used to connect point-to-point links together and uses the ISO’s non-proprietary version of HDLC. It can be used on either syn- chronous or asynchronous links. See Chapter 10 for more information on PPP. 20. A. The command copy running-config tftp (copy run tftp for short) will copy the router’s configuration to a TFTP host for backup purposes. See Chapter 7 for more information about TFTP hosts and Cisco routers. 21. A, B, C, D, F, G, H, I, J. The show cdp entry * command is used to gather detailed information about neighbor devices. See Chapter 7 for more information about CDP. 22. D. Cisco recommends that you break up collision domains with layer- 2 switches at the access layer, not the distribution layer. For more information on the distribution layer, see Chapter 1. 23. A, D. Cut-through and FragmentFree always read only a fixed amount of a frame. For more information on LAN switch types, see Chapter 2. 24. B. Cisco recommends that you use layer-2 switches, which break up collision domains, at the access layer. For more information on the access layer and collision domains, see Chapter 1. 25. C. You can use a letter, or combination of letters, followed by a ques- tion mark without a space to get all the commands starting with those letters from that prompt. For more editing and help information, see Chapter 4. 26. C. VLANs break up broadcast domains in switched networks. For more information on VLANs, please see Chapter 6. 27. A, B, C. Routing tables in a router keep track of where networks in a network are located, not hosts. They also keep track of the distance or cost to that remote network and which interface to exit to get to that remote network. For more information on routing tables, see Chapter 1.Copyright ©2000 SYBEX , Inc., Alameda, CA
  42. 42. lviii Answers to the Assessment Questions 28. C. The show users command will show you the virtual connections into your router. See Chapter 7 for more information about using Telnet. 29. B. Directly connected networks have the highest administrative dis- tance, or trustworthiness rating, of zero. See Chapter 5 for more infor- mation on IP routing. 30. D. Extended access lists use the numbers 100–199. This eliminates Answers B and C. To filter on an upper-layer protocol, you must use UDP or TCP in the protocol field. This eliminates Answer A. For more information on access lists, see Chapter 9. 31. A, B. When a port is in blocking state, no frames are forwarded. This is used to stop network loops. However, the blocked port will listen for BPDUs received on the port. For more information on STP, see Chapter 2. 32. D. The 1900 defaults to FragmentFree but can be changed to store and forward. For more information on LAN switch types, see Chapter 2. 33. B, E. There is no enable-encrypted password. The enable secret is encrypted by default and supersedes the enable password. To learn how to set the passwords on a router, see Chapter 4. 34. C. RIP has an administrative distance of 120 by default. See Chapter 5 for more information on IP routing. 35. B, C. If you receive an incomplete command, then you know that the command string is not done. Just press the up arrow key to receive the last command entered, and continue with the command by using your question mark. For more information on help and editing, see Chapter 4. 36. B. By default, static routes have an administrative distance of 1. The 175 represents an optional command that changes the default admin- istrative distance. See Chapter 5 for more information on IP routing. Copyright ©2000 SYBEX , Inc., Alameda, CA
  43. 43. Answers to the Assessment Questions lix 37. B. If a packet is received that is looking for a destination network that is not in the routing table, the router will drop the packet. See Chapter 5 for more information on IP routing. 38. B. The IPX address is 10 bytes (80 bits). The first four bytes are the network number, and the last six bytes are the node address. See Chapter 8 for more information on IPX. 39. A, B. The Network layer uses two different types of packets (called PDUs). The data packets route user data with routed protocols, and the route packets keep and maintain routing tables on routers within the internetwork with routing protocols. Examples of routed proto- cols are IP and IPX; examples of routing protocols are RIP, IGRP, and OSPF. For more information on PDUs, see Chapter 1. 40. C. Cisco has a proprietary frame tagging method called Inter-Switch Link (ISL), which keeps track of frames across a trunked link. For more information on VLANs, please see Chapter 6. 41. B, D. IPX RIP uses ticks (1/18 of a second) and then hop counts to determine the best way to an internetwork. See Chapter 8 for more information on IPX RIP. 42. C. Extended IP access lists use the numbers 100–199. See Chapter 9 for more information about access lists. 43. C. The command access-list 110 permit ip any any ( is the same as the any command) is a wildcard allowing any host or network. For more information on access lists, see Chapter 9. 44. C. Static VLANs are VLANs assigned to switch ports by an adminis- trator. For more information on VLANs, please see Chapter 6. 45. C. You can configure the switch type globally and set the switch type for all BRI interfaces, or you can set it at interface level if each BRI is connected to a different type of switch. See Chapter 10 for more infor- mation on ISDN.Copyright ©2000 SYBEX , Inc., Alameda, CA
  44. 44. lx Answers to the Assessment Questions 46. D. Backward-Explicit Congestion Notification (BECN) is used to send information back to an originating router telling it to slow down its transfer rate because the switch is congested. See Chapter 10 for more information on Frame Relay. 47. D. Data Link Connection Identifiers (DLCIs) are used to identify a PVC through a Frame Relay switch. See Chapter 10 for more infor- mation on Frame Relay. 48. B, C. You can add multiple encapsulations on an interface either by using the secondary command or by creating a subinterface. See Chapter 8 for more information on IPX and multiple encapsulations. 49. B. 50 seconds is the default time for changing from blocking to for- warding state. This is to allow enough time for all switches to update their STP database. For more information on STP, see Chapter 2. 50. D. You can telnet to a 1900, but not from a 1900 switch CLI. See Appendix B for an explanation of the 1900 switch commands. 51. D. To delete the dynamic entries in a MAC address table, use the com- mand clear mac-address-table dynamic from privileged mode. See Appendix B for an explanation of the 1900 switch commands. 52. B, C. By typing delete nvram, you delete the startup-config. How- ever, this does not delete the VTP configuration on the switch. You must also type delete vtp. See Appendix B for more information on the 1900 switch commands. 53. C. The ports 26 and 27 are considered A and B when viewing trunk information. See Appendix B for more on the 1900 switch commands. 54. A. The command show vtp statistics will give you the receive and transmit statistics of VTP on a switch. See Appendix B for an expla- nation of the 1900 switch commands. Copyright ©2000 SYBEX , Inc., Alameda, CA
  45. 45. Chapter Internetworking 1 THE CCNA EXAM TOPICS COVERED IN THIS CHAPTER INCLUDE THE FOLLOWING: Describe the benefits of a layered model Describe the main benefit of the OSI reference model Understand each of the seven layers of the OSI reference model and what they provide application developers Describe flow control and how it is used within an internetwork Understand how the Transport layer flow control mechanism works Describe how the OSI’s Network layer provides routing in an internetwork environment List the five conversion steps of data encapsulation Copyright ©2000 SYBEX , Inc., Alameda, CA
  46. 46. W elcome to the exciting world of internetworking. This first chapter will help you understand the basics of internetworking and how to connect networks using Cisco routers and switches. The Open Systems Interconnection (OSI) model will be discussed in detail in this chapter. The OSI model has seven hierarchical layers that were devel- oped to help different companies communicate between their disparate sys- tems. It is important to understand the OSI model as Cisco sees it, and that is how I will present the seven layers of the OSI model to you. Cisco has created a three-layer hierarchical network model that can help you build, implement, and maintain networks. By understanding this model, you can effectively build, maintain, and troubleshoot any size network. This chapter will give you both an introduction to the Cisco three-layer model and the details of each layer. Different types of devices are specified at different layers of the OSI model. It is important to understand the different types of cables and con- nectors used to connect these devices to a network. Cabling Cisco devices will be discussed with Ethernet LANs, WAN technologies, and even connect- ing a router or switch with a console connection. Cisco makes a large range of router, hub, and switch products. By under- standing the different products available from Cisco, you can understand which devices can meet the business requirements for your network. The product line for Cisco hubs, routers, and switches is discussed at the end of this chapter.Copyright ©2000 SYBEX , Inc., Alameda, CA