800 East 96th Street
Indianapolis, Indiana 46240 USA

Cisco Press

CCENT/CCNA ICND1Official Exam Certification Guide,
Second Edition

Wendell Odom,
CCIE No. 1624

1828xbook.fm Page i Thursday, July 26, 2007 3:10 PM

ii

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

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.

Corporate and Government Sales

The publisher offers excellent discounts on this book when ordered in quantity for bulk purchases or special sales,
which may include electronic versions and/or custom covers and content particular to your business, training goals,
marketing focus, and branding interests. For more information, please contact:

U.S. Corporate and Government Sales

1-800-382-3419

[email protected]

For sales outside the United States please contact:

International Sales

[email protected]

Feedback Information

At Cisco Press, our goal is to create in-depth technical books of the highest quality and value. Each book is crafted
with care and precision, undergoing rigorous development that involves the unique expertise of members of the
professional technical community.
Reader feedback is a natural continuation of this process. If you have any comments about how we could improve
the quality of this book, or otherwise alter it to better suit your needs, you can contact us through e-mail at
[email protected]. Please be sure to include the book title and ISBN in your message.
We greatly appreciate your assistance.

Book and Cover Designer:

Louisa Adair

Executive Editor:

Brett Bartow

Composition:

ICC Macmillan Inc.

Managing Editor:

Patrick Kanouse

Indexer:

Tim Wright

Senior Development Editor:

Christopher Cleveland

Proofreader:

Suzanne Thomas

Senior Project Editor:


Switching Official Exam Certification Guide

, Second Edition, and

CCNA Video Mentor

—
all from Cisco Press.

1828xbook.fm Page iv Thursday, July 26, 2007 3:10 PM

v

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


vii

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

Go to http://www.ciscopress.com/safarienabled.

■

Complete the brief registration form.

■

Enter the coupon code 6EM9-WNXL-7Z1E-9UL2-KAEC.
If you have difficulty registering on Safari Bookshelf or access-
ing the online edition, please e-mail customer-service@safari-
booksonline.com.

1828xbook.fm Page viii Thursday, July 26, 2007 3:10 PM

ix

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,

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

1828xbook.fm Page x Thursday, July 26, 2007 3:10 PM

xi

Contents

Foreword xxvi
Introduction xxvii

Part I Networking Fundamentals 3



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

1828xbook.fm Page xi Thursday, July 26, 2007 3:10 PM

xii

Improving Performance by Using Switches Instead of Hubs 58

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

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

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

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


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