Tài liệu CCENT/CCNA ICND1 phần 1 ppt

800 East 96th Street
Indianapolis, Indiana 46240 USA

Cisco Press

CCENT/CCNA ICND1


Official Exam Certification Guide,
Second Edition

Wendell Odom,
CCIE No. 1624

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CCENT/CCNA ICND1 Official Exam Certification Guide, Second Edition

Wendell Odom
Copyright© 2008 Cisco Systems, Inc.
Published by:
Cisco Press
800 East 96th Street
Indianapolis, IN 46240 USA
All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopying, recording, or by any information storage and retrieval system, without written
permission from the publisher, except for the inclusion of brief quotations in a review.
Printed in the United States of America

First Printing August 2007
Library of Congress Cataloging-in-Publication Data.
Odom, Wendell.
CCENT/CCNA ICND1 official exam certification guide / Wendell Odom.
p. cm.
ISBN 978-1-58720-182-0 (hardback w/cd) 1. Electronic data processing personnel--Certification. 2. Computer net-
works--Examinations--Study guides. I. Title.
QA76.3.O358 2007
004.6--dc22
2007029241
ISBN-13: 978-1-58720-182-0
ISBN-10: 1-58720-182-8

Warning and Disclaimer

This book is designed to provide information about the Cisco ICND1 (640-822), ICND2 (640-816), and CCNA
(640-802) exams. Every effort has been made to make this book as complete and accurate as possible, but no warranty
or fitness is implied.
The information is provided on an “as is” basis. The author, Cisco Press, and Cisco Systems, Inc. shall have neither
liability nor responsibility to any person or entity with respect to any loss or damages arising from the information
contained in this book or from the use of the discs or programs that may accompany it.
The opinions expressed in this book belong to the author and are not necessarily those of Cisco Systems, Inc.

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Trademark Acknowledgments

All terms mentioned in this book that are known to be trademarks or service marks have been appropriately

capitalized. Cisco Press or Cisco Systems, Inc. cannot attest to the accuracy of this information. Use of a term in this
book should not be regarded as affecting the validity of any trademark or service mark.

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Publisher:

Paul Boger

Copy Editor:

Gayle Johnson and Bill McManus

Associate Publisher:

Dave Dusthimer

Technical Editors:

Teri Cook, Brian D’Andrea,
and Steve Kalman

Cisco Representative:

Anthony Wolfenden

Editorial Assistant:

Vanessa Evans

Cisco Press Program Manager:

Jeff Brady

Book and Cover Designer:

Louisa Adair

Executive Editor:

Brett Bartow

Composition:

ICC Macmillan Inc.

Managing Editor:

Patrick Kanouse

Indexer:

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Senior Development Editor:

Christopher Cleveland

Proofreader:

Suzanne Thomas

Senior Project Editor:

San Dee Phillips and Meg Shaw

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About the Author

Wendell Odom

, CCIE No. 1624, has been in the networking industry since 1981. He
currently teaches QoS, MPLS, and CCNA courses for Skyline Advanced Technology
Services (). He has also worked as a network engineer,
consultant, systems engineer, instructor, and course developer. He is the author of all
previous editions of the

CCNA Exam Certification Guide

, as well as the

Cisco QOS Exam
Certification Guide

, Second Edition,

Computer Networking First-Step

,

CCIE Routing and

Switching Official Exam Certification Guide

, Second Edition, and

CCNA Video Mentor

—
all from Cisco Press.

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About the Technical Reviewers

Teri Cook

(CCSI, CCDP, CCNP, CCDA, CCNA, MCT, and MCSE 2000/2003: Security)
has more than ten years of experience in the IT industry. She has worked with different
types of organizations in the private business and DoD sectors, providing senior-level
network and security technical skills in the design and implementation of complex
computing environments. Since obtaining her certifications, Teri has been committed to
bringing quality IT training to IT professionals as an instructor. She is an outstanding
instructor who uses real-world experience to present complex networking technologies. As
an IT instructor, Teri has been teaching Cisco classes for more than five years.

Brian D’Andrea

(CCNA, CCDA, MCSE, A+, and Net+) has 11 years of IT experience in
both medical and financial environments, where planning and supporting critical

networking technologies were his primary responsibilities. For the last five years he has
dedicated himself to technical training. Brian spends most of his time with The Training
Camp, an IT boot camp provider. Using his real-world experience and his ability to break
difficult concepts into a language that students can understand, Brian has successfully
trained hundreds of students for both work and certification endeavors.

Stephen Kalman

is a data security trainer. He is the author or tech editor of more than
20 books, courses, and CBT titles. His most recent book is

Web Security Field Guide

,
published by Cisco Press. In addition to those responsibilities he runs a consulting
company, Esquire Micro Consultants, which specializes in network security assessments
and forensics.
Mr. Kalman holds SSCP, CISSP, ISSMP, CEH, CHFI, CCNA, CCSA (Checkpoint), A+,
Network+ and Security+ certifications and is a member of the New York State Bar.

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Dedication

For Brett Bartow. Thanks for being such a steady, insightful, and incredibly trustworthy
guide through the publishing maze.

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Acknowledgments

The team who helped produce this book has been simply awesome. Everyone who touched
this book has made it better, and they’ve been particularly great at helping catch the errors
that always creep into the manuscript.
Brian, Teri, and Steve all did a great job TEing the book. Besides helping a lot with
technical accuracy, Brian made a lot of good suggestions about traps that he sees when
teaching CCNA classes, helping the book avoid those same pitfalls. Teri’s ability to see
each phrase in the context of an entire chapter, or the whole book, was awesome, helping
catch things that no one would otherwise catch. Steve spent most of his TE time on the
ICND2 book, but he did lend great help with this one, particularly with his reviews of the
security-oriented topics, an area in which he’s an expert. And more so than any other book
I’ve written, the TEs really sunk their teeth into the specifics of every example, helping
catch errors. Thanks so much!
Another (ho-hum) all-star performance from Chris Cleveland, who developed the book.
Now I empathize with sports writers who have to write about the local team’s star who bats
.300, hits 40 homers, and drives in 100 runs, every year, for his whole career. How many
ways can you say he does a great job? I’ll keep it simple: Thanks, Chris.
The wonderful and mostly hidden production folks did their usual great job. When every
time I see how they reworded something, and think, “Wow; why didn’t I write that?”, it
makes me appreciate the kind of team we have at Cisco Press. The final copy edit, figure
review, and pages review process required a fair amount of juggling and effort as well –
thanks to Patrick’s team, especially San Dee, Meg, Tonya, for working so well with all the
extra quality initiatives we’ve implemented. Thanks to you all!
Additionally, several folks who didn’t have any direct stake in the book also helped it along.
Thanks to Frank Knox for the discussions on the exams, why they’re so difficult, and about
troubleshooting. Thanks to Rus Healy for the help with wireless. Thanks to the Mikes at

Skyline for making my schedule work to get this book (and the ICND2 book) out the door.
And thanks to the course and exam teams at Cisco for the great early communications and
interactions about the changes to the courses and exams.
Finally, thanks to my wife Kris for all her support with my writing efforts, her prayers,
and her understanding when the deadline didn’t quite match with our vacation plans this
summer. And thanks to Jesus Christ—all this effort is just striving after the wind without
Him.

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Contents at a Glance

Foreword xxvi
Introduction xxvii

Part I Networking Fundamentals 3

Chapter 1 Introduction to Computer Networking Concepts 5
Chapter 2 The TCP/IP and OSI Networking Models 17
Chapter 3 Fundamentals of LANs 41
Chapter 4 Fundamentals of WANs 71
Chapter 5 Fundamentals of IP Addressing and Routing 93
Chapter 6 Fundamentals of TCP/IP Transport, Applications,
and Security 129

Part II LAN Switching 165

Chapter 7 Ethernet LAN Switching Concepts 167
Chapter 8 Operating Cisco LAN Switches 197
Chapter 9 Ethernet Switch Configuration 231
Chapter 10 Ethernet Switch Troubleshooting 267
Chapter 11 Wireless LANs 299

Part III IP Routing 329

Chapter 12 IP Addressing and Subnetting 331
Chapter 13 Operating Cisco Routers 399
Chapter 14 Routing Protocol Concepts and Configuration 435
Chapter 15 Troubleshooting IP Routing 471

Part IV Wide-Area Networks 509

Chapter 16 WAN Concepts 511
Chapter 17 WAN Configuration 539

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Part V Final Preparation 563

Chapter 18 Final Preparation 565

Part VI Appendixes 575

Appendix A Answers to the “Do I Know This Already?” Quizzes 577
Appendix B Decimal to Binary Conversion Table 591
Appendix C ICND1 Exam Updates: Version 1.0 595
Glossary 599
Index 624

Part VII CD-Only

Appendix C ICND1 Exam Updates: Version 1.0
Appendix D Subnetting Practice
Appendix E Subnetting Reference Pages
Appendix F Additional Scenarios
Appendix G Subnetting Video Reference
Appendix H Memory Tables
Appendix I Memory Tables Answer Key
Appendix J ICND1 Open-Ended Questions

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Contents

Foreword xxvi
Introduction xxvii

Part I Networking Fundamentals 3

Chapter 1 Introduction to Computer Networking Concepts 5

Perspectives on Networking 5

The Flintstones Network: The First Computer Network? 8

Chapter 2 The TCP/IP and OSI Networking Models 17

“Do I Know This Already?” Quiz 18

Foundation Topics 21

The TCP/IP Protocol Architecture 22

The TCP/IP Application Layer 23
The TCP/IP Transport Layer 25
The TCP/IP Internet Layer 27
The TCP/IP Network Access Layer 28
Data Encapsulation Terminology 30

The OSI Reference Model 32

Comparing OSI and TCP/IP 32
OSI Layers and Their Functions 34
OSI Layering Concepts and Benefits 35
OSI Encapsulation Terminology 36

Exam Preparation Tasks 38

Review all the Key Topics 38

Complete the Tables and Lists from Memory 38
Definitions of Key Terms 38
OSI Reference 39

Chapter 3 Fundamentals of LANs 41

“Do I Know This Already?” Quiz 41

Foundation Topics 45

An Overview of Modern Ethernet LANs 45
A Brief History of Ethernet 48

The Original Ethernet Standards: 10BASE2 and 10BASE5 48
Repeaters 50
Building 10BASE-T Networks with Hubs 51

Ethernet UTP Cabling 52

UTP Cables and RJ-45 Connectors 52
Transmitting Data Using Twisted Pairs 54
UTP Cabling Pinouts for 10BASE-T and 100BASE-TX 55
1000BASE-T Cabling 58

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Improving Performance by Using Switches Instead of Hubs 58

Increasing Available Bandwidth Using Switches 61
Doubling Performance by Using Full-Duplex Ethernet 62
Ethernet Layer 1 Summary 63

Ethernet Data-Link Protocols 63

Ethernet Addressing 64
Ethernet Framing 65
Identifying the Data Inside an Ethernet Frame 67
Error Detection 68

Exam Preparation Tasks 69

Review All the Key Topics 69
Complete the Tables and Lists from Memory 69
Definitions of Key Terms 69

Chapter 4 Fundamentals of WANs 71

“Do I Know This Already?” Quiz 71

Foundation Topics 74

OSI Layer 1 for Point-to-Point WANs 74

WAN Connections from the Customer Viewpoint 77
WAN Cabling Standards 78
Clock Rates, Synchronization, DCE, and DTE 80
Building a WAN Link in a Lab 81
Link Speeds Offered by Telcos 82

OSI Layer 2 for Point-to-Point WANs 83

HDLC 83
Point-to-Point Protocol 85
Point-to-Point WAN Summary 85

Frame Relay and Packet-Switching Services 86

The Scaling Benefits of Packet Switching 86
Frame Relay Basics 87

Exam Preparation Tasks 91

Review All the Key Topics 91
Complete the Tables and Lists from Memory 91
Definitions of Key Terms 91

Chapter 5 Fundamentals of IP Addressing and Routing 93

“Do I Know This Already?” Quiz 93

Foundation Topics 98

Overview of Network Layer Functions 98

Routing (Forwarding) 99
PC1’s Logic: Sending Data to a Nearby Router 100
R1 and R2’s Logic: Routing Data Across the Network 100
R3’s Logic: Delivering Data to the End Destination 100

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Network Layer Interaction with the Data Link Layer 101
IP Packets and the IP Header 102
Network Layer (Layer 3) Addressing 103
Routing Protocols 104

IP Addressing 105

IP Addressing Definitions 105
How IP Addresses Are Grouped 106
Classes of Networks 107
The Actual Class A, B, and C Network Numbers 109
IP Subnetting 110

IP Routing 114

Host Routing 114
Router Forwarding Decisions and the IP Routing Table 115

IP Routing Protocols 118
Network Layer Utilities 121

Address Resolution Protocol and the Domain Name System 121
DNS Name Resolution 122
The ARP Process 122
Address Assignment and DHCP 123

ICMP Echo and the ping Command 125

Exam Preparation Tasks 126

Review All the Key Topics 126
Complete the Tables and Lists from Memory 127
Definitions of Key Terms 127

Chapter 6 Fundamentals of TCP/IP Transport, Applications, and Security 129

“Do I Know This Already?” Quiz 129

Foundation Topics 133

TCP/IP Layer 4 Protocols: TCP and UDP 133

Transmission Control Protocol 134
Multiplexing Using TCP Port Numbers 135
Popular TCP/IP Applications 138
Error Recovery (Reliability) 140
Flow Control Using Windowing 141
Connection Establishment and Termination 142
Data Segmentation and Ordered Data Transfer 144
User Datagram Protocol 145

TCP/IP Applications 146

QoS Needs and the Impact of TCP/IP Applications 146
The World Wide Web, HTTP, and SSL 149
Universal Resource Locators 150

Finding the Web Server Using DNS 150
Transferring Files with HTTP 152

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Network Security 153

Perspectives on the Sources and Types of Threats 154
Firewalls and the Cisco Adaptive Security Appliance (ASA) 158
Anti-x 160
Intrusion Detection and Prevention 160
Virtual Private Networks (VPN) 161

Exam Preparation Tasks 163

Review All the Key Topics 163
Complete the Tables and Lists from Memory 163
Definitions of Key Terms 163

Part II LAN Switching 165

Chapter 7 Ethernet LAN Switching Concepts 167

“Do I Know This Already?” Quiz 167

Foundation Topics 171

LAN Switching Concepts 171

Historical Progression: Hubs, Bridges, and Switches 171
Switching Logic 174
The Forward Versus Filter Decision 175
How Switches Learn MAC Addresses 177
Flooding Frames 178
Avoiding Loops Using Spanning Tree Protocol 179
Internal Processing on Cisco Switches 180
LAN Switching Summary 182

LAN Design Considerations 183

Collision Domains and Broadcast Domains 183
Collision Domains 183
Broadcast Domains 184
The Impact of Collision and Broadcast Domains on LAN Design 185
Virtual LANs (VLAN) 187
Campus LAN Design Terminology 188
Ethernet LAN Media and Cable Lengths 191

Exam Preparation Tasks 194

Review All the Key Topics 194
Complete the Tables and Lists from Memory 194
Definitions of Key Terms 195

Chapter 8 Operating Cisco LAN Switches 197

“Do I Know This Already?” Quiz 197

Foundation Topics 200

Accessing the Cisco Catalyst 2960 Switch CLI 200

Cisco Catalyst Switches and the 2960 Switch 201

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Switch Status from LEDs 202
Accessing the Cisco IOS CLI 205
CLI Access from the Console 206
Accessing the CLI with Telnet and SSH 208
Password Security for CLI Access 208
User and Enable (Privileged) Modes 210
CLI Help Features 211
The debug and show Commands 213

Configuring Cisco IOS Software 214

Configuration Submodes and Contexts 215
Storing Switch Configuration Files 217
Copying and Erasing Configuration Files 220
Initial Configuration (Setup Mode) 221

Exam Preparation Tasks 226

Review All the Key Topics 226
Complete the Tables and Lists from Memory 226

Definitions of Key Terms 226
Command References 226

Chapter 9 Ethernet Switch Configuration 231

“Do I Know This Already?” Quiz 231

Foundation Topics 235

Configuration of Features in Common with Routers 235

Securing the Switch CLI 235
Configuring Simple Password Security 236
Configuring Usernames and Secure Shell (SSH) 239
Password Encryption 242
The Two Enable Mode Passwords 244
Console and vty Settings 245
Banners 245
History Buffer Commands 246
The logging synchronous and exec-timeout Commands 247

LAN Switch Configuration and Operation 248

Configuring the Switch IP Address 248
Configuring Switch Interfaces 251
Port Security 253
VLAN Configuration 256
Securing Unused Switch Interfaces 259

Exam Preparation Tasks 261

Review All the Key Topics 261
Complete the Tables and Lists from Memory 261
Definitions of Key Terms 262
Command References 262

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Chapter 10 Ethernet Switch Troubleshooting 267

“Do I Know This Already?” Quiz 267

Foundation Topics 271

Perspectives on Network Verification and Troubleshooting 271

Attacking Sim Questions 271
Simlet Questions 272
Multiple-Choice Questions 273
Approaching Questions with an Organized Troubleshooting Process 273
Isolating Problems at Layer 3, and Then at Layers 1 and 2 275
Troubleshooting as Covered in This Book 276

Verifying the Network Topology with Cisco Discovery Protocol 277
Analyzing Layer 1 and 2 Interface Status 282

Interface Status Codes and Reasons for Nonworking States 282
Interface Speed and Duplex Issues 284

Common Layer 1 Problems on Working Interfaces 287

Analyzing the Layer 2 Forwarding Path with the MAC Address Table 289

Analyzing the Forwarding Path 292
Port Security and Filtering 293

Exam Preparation Tasks 295

Review All the Key Topics 295
Complete the Tables and Lists from Memory 295
Definitions of Key Terms 295
Command References 295

Chapter 11 Wireless LANs 299
“Do I Know This Already?” Quiz 299
Foundation Topics 302
Wireless LAN Concepts 302
Comparisons with Ethernet LANs 302
Wireless LAN Standards 304
Modes of 802.11 Wireless LANs 305
Wireless Transmissions (Layer 1) 307
Wireless Encoding and Nonoverlapping DSSS Channels 309
Wireless Interference 311
Coverage Area, Speed, and Capacity 311
Media Access (Layer 2) 314
Deploying WLANs 315
Wireless LAN Implementation Checklist 315
Step 1: Verify the Existing Wired Network 316
Step 2: Install and Configure the AP’s Wired and IP Details 317

Step 3: Configure the AP’s WLAN Details 317
Step 4: Install and Configure One Wireless Client 318
Step 5: Verify That the WLAN Works from the Client 319
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