xli — Chapter 10, “Ethernet Switch Troubleshooting,” focuses on how to tell if the switch is doing what it is supposed to, mainly through the use of show commands. — Chapter 11, “Wireless LANs,” explains the basic operation concepts of wireless LANs, along with addressing some of the most common security concerns. ■ Part III: IP Routing — Chapter 12, “IP Addressing and Subnetting,” completes the explanation of subnetting that was introduced in Chapter 5. More importantly, it describes in detail how to perform the math and processes to find the answers to many varieties of subnetting questions. — Chapter 13, “Operating Cisco Routers,” is like Chapter 8, but with a focus on routers instead of switches. — Chapter 14, “Routing Protocol Concepts and Configuration,” explains how routers forward (route) IP packets and how IP routing protocols work to find all the best routes to each subnet. This chapter includes the details of how to configure static routes and RIP version 2. — Chapter 15, “Troubleshooting IP Routing,” suggests hints and tips about how to troubleshoot problems related to layer 3 routing, including a description of several troubleshooting tools. ■ Part IV: Wide-Area Networks — Chapter 16, “WAN Concepts,” completes the conceptual materials for WANs, continuing the coverage from Chapter 4 by touching on Internet access technologies such as DSL and cable. It also covers the concepts of Network Address Translation (NAT). — Chapter 17, “WAN Configuration,” completes the main technical topics, focusing on a few small WAN configuration tasks. It also covers the WAN configuration tasks and NAT configuration using Cisco Security Device Manager (SDM). ■ Part V: Final Preparation — Chapter 18, “Final Preparation,” suggests a plan for final preparation after you have finished the core parts of the book. It also explains the many study options available in the book. ■ Part VI: Appendixes (in the Book) — Appendix A, “Answers to the “Do I Know This Already?” Quizzes,” includes the answers to all the questions from Chapters 1 through 17. 1828xbook.fm Page xli Thursday, July 26, 2007 3:10 PM xlii — Appendix B, “Decimal to Binary Conversion Table,” lists decimal values 0 through 255, along with their binary equivalents. — Appendix C, “ICND1 Exam Updates,” covers a variety of short topics that either clarify or expand on topics covered earlier in the book. This appendix is updated from time to time and is posted at http://www.ciscopress.com/ccna. The most recent version available at the time this book was published is included in this book as Appendix C. (The first page of the appendix includes instructions on how to check to see if a later version of Appendix C is available online.) — The glossary defines all the terms listed in the “Definitions of Key Terms” section at the conclusion of Chapters 1 through 17. ■ Part VII: Appendixes (on the CD) The following appendixes are available in PDF format on the CD that accompanies this book: — Appendix D, “Subnetting Practice,” includes a large number of subnetting practice problems. It gives the answers as well as explanations of how to use the processes described in Chapter 12 to find the answers. — Appendix E, “Subnetting Reference Pages.” Chapter 12 explains in detail how to calculate the answers to many subnetting questions. This appendix summarizes the process of finding the answers to several key questions, with the details on a single page. The goal is to give you a handy reference page to refer to when you’re practicing subnetting. — Appendix F, “Additional Scenarios.” One method to improve your troubleshooting and network analysis skills is to examine as many unique network scenarios as possible, think about them, and then get some feedback on whether you came to the right conclusions. This appendix provides several such scenarios. — Appendix G, “Subnetting Video Reference.” The DVD includes several subnetting videos that show you how to use the processes covered in Chapter 12. This appendix contains copies of the key elements from those videos, which may be useful when you’re watching the videos (so that you do not have to keep moving back and forth in the video). — Appendix H, “Memory Tables,” contains the key tables and lists from each chapter, with some of the content removed. You can print this appendix and, as a memory exercise, complete the tables and lists. The goal is to help you memorize facts that can be useful on the exams. — Appendix I, “Memory Tables Answer Key,” contains the answer key for the exercises in Appendix H. 1828xbook.fm Page xlii Thursday, July 26, 2007 3:10 PM xliii — Appendix J, “ICND1 Open-Ended Questions,” is a holdover from the previous edition of this book. The first edition had some open-ended questions to help you study for the exam, but the newer features make these questions unnecessary. For convenience, the old questions are included here, unedited since the last edition. How to Use This Book to Prepare for the ICND1 (640–822) Exam and CCENT Certification This book was designed with two primary goals in mind: to help you study for the ICND1 exam (and get your CCENT certification), and to help you study for the CCNA exam by using both this book and the CCNA ICND2 Official Exam Certification Guide. Using this book to prepare for the ICND1 exam is pretty straightforward. You read each chapter in succession and follow the study suggestions in Chapter 18. For Chapters 1 through 17, you have some choices as to how much of the chapter you read. In some cases, you may already know most or all of the information covered in a given chapter. To help you decide how much time to spend on each chapter, the chapters begin with a “Do I Know This Already?” quiz. If you get all the quiz questions correct, or if you miss just one, you may want to skip to the “Exam Preparation Tasks” section at the end of the chapter and perform those activities. Figure I-2 shows the overall plan. Figure I-2 How to Approach Each Chapter of This Book When you have completed Chapters 1 through 17, you can use the guidance listed in Chapter 18 to perform the rest of the exam preparation tasks. That chapter includes the following suggestions: ■ Check http://www.ciscopress.com for the latest copy of Appendix C, which may include additional topics for study. Ta ke the “Do I Know This Already Quiz” Read “Foundation Topics” Section Read/do “Exam Preparation Tasks” To Next Chapter Miss more than 1: Miss 1 or less, but want more study Miss 1 or less, want to move on 1828xbook.fm Page xliii Thursday, July 26, 2007 3:10 PM xliv ■ Practice subnetting using the tools available in the CD appendixes. ■ Repeat the tasks in all the chapters’ “Exam Preparation Tasks” chapter-ending sections. ■ Review the scenarios in CD Appendix F. ■ Review all the “Do I Know This Already?” questions. ■ Practice the exam using the exam engine. How to Use These Books to Prepare for the CCNA 640–802 Exam If you plan to get your CCNA certification using the one-exam option of taking the CCNA 640-802 exam, you can use this book with the CCNA ICND2 Official Exam Certification Guide. If you haven’t yet bought either book, you generally can get the pair cheaper by buying both books as a two-book set called the CCNA Certification Library. These two books were designed to be used together when you study for the CCNA exam. You have two good options for the order in which to read the two books. The first and most obvious option is to read this book and then move on to the ICND2 book. The other option is to read all of ICND1’s coverage of one topic area, and then read ICND2’s coverage of the same topics, and then return to ICND1. Figure I-3 outlines my suggested plan for reading the two books. Figure I-3 Reading Plan When You’re Studying for the CCNA Exam Both reading plan options have some benefits. Moving back and forth between books helps you focus on one general topic at a time. However, note that there is some overlap between the two exams, so there is some overlap between the two books as well. From reader Network Fundamentals Final Preparation Wide-Area Networks IP Routing LAN Switching ICND1 Exam Certification Guide Start here LAN Switching IP Routing Routing Protocols Wide-Area Networks Scaling the IP Address Space Final Preparation ICND2 Exam Certification Guide 1828xbook.fm Page xliv Thursday, July 26, 2007 3:10 PM xlv comments about the previous edition of these books, readers who were new to networking tended to do better by completing all of the first book and then moving on to the second. Readers who had more experience and knowledge before starting the books tended to prefer following a reading plan like the one shown in Figure I-3. Note that for final preparation, you can use the final chapter (Chapter 18) of the ICND2 book rather than the “Final Preparation” chapter (Chapter 18) of this book. Chapter 18 of ICND2 covers the same basic activities as does this book’s Chapter 18, with reminders of any exam preparation materials from this book that should be useful. In addition to the flow shown in Figure I-3, when you study for the CCNA exam (rather than the ICND1 and ICND2 exams), it is important to master IP subnetting before moving on to the IP routing and routing protocol parts of the ICND2 book. The ICND2 book does not review subnetting or the underlying math, assuming that you know how to find the answers. Those ICND2 chapters, particularly Chapter 5 (“VLSM and Route Summarization”), are much easier to understand if you can do the related subnetting math pretty easily. For More Information If you have any comments about this book, you can submit them via http://www.ciscopress.com. Just go to the website, select Contact Us, and enter your message. Cisco might occasionally make changes that affect the CCNA certification. You should always check http://www.cisco.com/go/ccna and http://www.cisco.com/go/ccent for the latest details. The CCNA certification is arguably the most important Cisco certification, although the new CCENT certification might surpass CCNA in the future. CCNA certainly is the most popular Cisco certification to date. It’s required for several other certifications, and it’s the first step in distinguishing yourself as someone who has proven knowledge of Cisco. The CCENT/CCNA ICND1 Official Exam Certification Guide is designed to help you attain both CCENT and CCNA certification. This is the CCENT/CCNA ICND1 certification book from the only Cisco-authorized publisher. We at Cisco Press believe that this book can help you achieve CCNA certification, but the real work is up to you! I trust that your time will be well spent. 1828xbook.fm Page xlv Thursday, July 26, 2007 3:10 PM Cisco Published ICND1 Exam Topics* Covered in This Part: Describe the operation of data networks ■ Describe the purpose and functions of various network devices ■ Select the components required to meet a given network specification ■ Use the OSI and TCP/IP models and their associated protocols to explain how data flows in a network ■ Describe common networking applications including web applications ■ Describe the purpose and basic operation of the protocols in the OSI and TCP models ■ Describe the impact of applications (Voice Over IP and Video Over IP) on a network ■ Describe the components required for network and Internet communications ■ Identify and correct common network problems at Layers 1, 2, 3, and 7 using a layered model approach Implement an IP addressing scheme and IP services to meet network requirements for a small branch office ■ Describe the need for and role of addressing in a network ■ Create and apply an addressing scheme to a network ■ Describe and verify DNS operation Implement a small routed network ■ Describe basic routing concepts (including: packet forwarding, router lookup process) ■ Select the appropriate media, cables, ports, and connectors to connect routers to other network devices and hosts Identify security threats to a network and describe general methods to mitigate those threats ■ Explain today’s increasing network security threats and the need to implement a comprehensive security policy to mitigate the threats ■ Explain general methods to mitigate common security threats to network devices, hosts, and applications ■ Describe the functions of common security appliances and applications ■ Describe security recommended practices including initial steps to secure network devices *Always check http://www.cisco.com for the latest posted exam topics. 1828xbook.fm Page 2 Thursday, July 26, 2007 3:10 PM Part I: Networking Fundamentals Chapter 1 Introduction to Computer Networking Concepts Chapter 2 The TCP/IP and OSI Networking Models Chapter 3 Fundamentals of LANs Chapter 4 Fundamentals of WANs Chapter 5 Fundamentals of IP Addressing and Routing Chapter 6 Fundamentals of TCP/IP Transport, Applications, and Security 1828xbook.fm Page 3 Thursday, July 26, 2007 3:10 PM 1828xbook.fm Page 4 Thursday, July 26, 2007 3:10 PM C H A P T E R 1 Introduction to Computer Networking Concepts This chapter gives you a light-hearted perspective about networks, how they were originally created, and why networks work the way they do. Although no specific fact from this chapter happens to be on any of the CCNA exams, this chapter helps you prepare for the depth of topics you will start to read about in Chapter 2, “The TCP/IP and OSI Networking Models.” If you are brand new to networking, this short introductory chapter will help you get ready for the details to follow. If you already understand some of the basics of TCP/IP, Ethernet, switches, routers, IP addressing, and the like, go ahead and skip on to Chapter 2. The rest of you will probably want to read through this short introductory chapter before diving into the details. Perspectives on Networking So, you are new to networking. You might have seen or heard about different topics relating to networking, but you are only just now getting serious about learning the details. Like many people, your perspective about networks might be that of a user of the network, as opposed to the network engineer who builds networks. For some, your view of networking might be based on how you use the Internet, from home, using a high-speed Internet connection. Others of you might use a computer at a job or at school, again connecting to the Internet; that computer is typically connected to a network via some cable. Figure 1-1 shows both perspectives of networking. Figure 1-1 End-User Perspective on Networks The top part of the figure shows a typical high-speed cable Internet user. The PC connects to a cable modem using an Ethernet cable. The cable modem then connects to a cable TV (CATV) outlet on the wall using a round coaxial cable—the same kind of cable used to connect your TV to the CATV wall outlet. Because cable Internet services provide service Home User PC with Ethernet Card Office User PC with Ethernet Card The Internet Ethernet Cable CATV Cable Ethernet Cable 1828xbook.fm Page 5 Thursday, July 26, 2007 3:10 PM 6 Chapter 1: Introduction to Computer Networking Concepts continuously, the user can just sit down at the PC and start sending e-mail, browsing websites, making Internet phone calls, and using other tools and applications as well. Similarly, an employee of a company or a student at a university views the world as a connection through a wall plug. Typically, this connection uses a type of local-area network (LAN) called Ethernet. Instead of needing a cable modem, the PC connects directly to an Ethernet-style socket in a wall plate (the socket is much like the typical socket used for telephone cabling today, but the connector is a little larger). As with high-speed cable Internet connections, the Ethernet connection does not require the PC user to do anything first to connect to the network—it is always there waiting to be used, similar to the power outlet. From the end-user perspective, whether at home, at work, or at school, what happens behind the wall plug is magic. Just as most people do not really understand how cars work, how TVs work, and so on, most people who use networks do not understand how they work. Nor do they want to! But if you have read this much into Chapter 1, you obviously have a little more interest in networking than a typical end user. By the end of this book, you will have a pretty thorough understanding of what is behind that wall plug in both cases shown in Figure 1-1. The CCNA exams, and particularly the ICND1 (640-822) exam, focus on two major branches of networking concepts, protocols, and devices. One of these two major branches is called enterprise networking. An enterprise network is a network created by one corporation, or enterprise, for the purpose of allowing its employees to communicate. For example, Figure 1-2 shows the same type of PC end-user shown in Figure 1-1, who is now communicating with a web server through the enterprise network (represented by a cloud) created by Enterprise #2. The end-user PC can communicate with the web server to do something useful for the company—for instance, the user might be on the phone with a customer, with the user typing in the customer’s new order in the ordering system that resides in the web server. Figure 1-2 An Example Representation of an Enterprise Network Office User PC with Ethernet Card Ethernet Cable Web Server Enterprise #2 1828xbook.fm Page 6 Thursday, July 26, 2007 3:10 PM . Transport, Applications, and Security 1 828 xbook.fm Page 3 Thursday, July 26 , 20 07 3:10 PM 1 828 xbook.fm Page 4 Thursday, July 26 , 20 07 3:10 PM C H A P T E R 1 Introduction. 1 828 xbook.fm Page 2 Thursday, July 26 , 20 07 3:10 PM Part I: Networking Fundamentals Chapter 1 Introduction to Computer Networking Concepts Chapter 2 The