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Mike Meyers’

CompTIA Network+® Guide to Managing and

Troubleshooting Networks

Third Edition

(Exam N10-005)

This page intentionally left blank

Mike Meyers’

CompTIA Network+® Guide to Managing and

Troubleshooting Networks

Third Edition

(Exam N10-005)

Mike Meyers

New York Chicago San Francisco Lisbon London Madrid Mexico City Milan

New Delhi San Juan Seoul Singapore Sydney Toronto

BaseTech

Copyright © 2012 by the McGraw-Hill Companies. All rights reserved. Printed in the United States of America. Except as permitted under the Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of publisher, with the exception that the program listings may be entered, stored, and executed in a computer system, but they may not be reproduced for publication.

ISBN: 978-0-07-179981-2

MHID: 0-07-179981-8

The material in this eBook also appears in the print version of this title: ISBN: 978-0-07-178911-0, MHID: 0-07-178911-1.

All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefi t of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps.

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McGraw-Hill is an independent entity from CompTIA®. This publication and digital content may be used in assisting students to prepare for the CompTIA Network+ exam. Neither CompTIA nor McGraw-Hill warrants that use of this publication and digital content will ensure passing any exam. CompTIA and CompTIA Network+ are trademarks or registered trademarks of CompTIA in the United States and/or other countries. All other trademarks are trademarks of their respective owners.

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This is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGrawHill”) and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s prior consent. You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited. Your right to use the work may be terminated if you fail to comply with these terms.

THE WORK IS PROVIDED “AS IS.” McGRAW-HILL AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THE ACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK, INCLUDING ANY INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE, AND EXPRESSLY DISCLAIM ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. McGraw-Hill and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free. Neither McGraw-Hill nor its licensors shall be liable to you or anyone else for any inaccuracy, error or omission, regardless of cause, in the work or for any damages resulting therefrom. McGraw-Hill has no responsibility for the content of any information accessed through the work. Under no circumstances shall McGraw-Hill and/ or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise.

E-book conversion by codeMantra

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About the Author■■ Michael Meyers is the industry’s leading authority on CompTIA Network+ certifica- tion. He is the president and founder of Total Seminars, LLC, a major provider of PC and network repair seminars for thousands of organizations throughout the world, and a member of CompTIA.

Mike has written numerous popular textbooks, including the best-selling Mike Meyers’ CompTIA A+® Guide to Managing & Troubleshooting PCs, Mike Meyers’ CompTIA A+® Guide to Essentials, and Mike Meyers’ CompTIA A+® Guide to Operating Systems.

About the Contributor Scott Jernigan wields a mighty red pen as Editor in Chief for Total Seminars. With a Master of Arts degree in Medieval History, Scott feels as much at home in the musty archives of London as he does in the warm CRT glow of Total Seminars’ Houston head- quarters. After fleeing a purely academic life, he dove headfirst into IT, working as an instructor, editor, and writer.

Scott has written, edited, and contributed to dozens of books on computer liter- acy, hardware, operating systems, networking, and certification, including Computer Literacy—Your Ticket to IC3 Certification, and co-authoring with Mike Meyers the All-in- One CompTIA Strata® IT Fundamentals Exam Guide.

Scott has taught computer classes all over the United States, including stints at the United Nations in New York and the FBI Academy in Quantico. Practicing what he preaches, Scott is a CompTIA A+ and CompTIA Network+ certified technician, a Microsoft Certified Professional, a Microsoft Office User Specialist, and Certiport Inter- net and Computing Core Certified.

About the Technical Editor Jonathan S. Weissman earned his master’s degree in Computer and Information Science from Brooklyn College (CUNY), and holds nineteen industry certifications, including Cisco CCNA, CompTIA Security+, CompTIA i-Net+, CompTIA Network+, CompTIA A+, CompTIA Linux+, Novell CNE, Novell CNA, Microsoft Office Master, Microsoft MCAS Word, Microsoft MCAS PowerPoint, Microsoft MCAS Excel, Microsoft MCAS Access, Microsoft MCAS Outlook, and Microsoft MCAS Vista.

Jonathan is a tenured Assistant Professor of Computing Sciences at Finger Lakes Community College, in Canandaigua, NY, and also teaches graduate and under- graduate computer science courses at nearby Rochester Institute of Technology. In addi- tion, Jonathan does computer, network, and security consulting for area businesses and individuals.

Between FLCC and RIT, Jonathan has taught nearly two dozen different computer science courses, including networking, security, administration, forensics, program- ming, operating systems, hardware, and software.

Students evaluating his teaching emphasize that he simplifies their understanding of difficult topics, while at the same time makes the class interesting and entertaining.

Jonathan completely designed and configured FLCC’s newest Networking & Secu- rity Lab. Serving as IT Program Coordinator, he rewrote FLCC’s Information Technol- ogy course requirements for the degree, keeping it current with the changes in industry over the years.

This textbook is just one of the many that Jonathan has edited for thoroughness and accuracy.

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vii

Acknowledgments■■ I’d like to acknowledge the many people who contributed their talents to make this book possible:

To Tim Green, my acquisitions editor at McGraw-Hill: Didn’t think I’d get the book out this quickly, did you? Thanks for your superb support and encouragement, as always.

To my in-house Editor-in-Chief, Scott Jernigan: Didn’t think we’d get the book out that fast, did you? How many 85s do you have now? Pelape still smokes them all in DPS.

To Jonathan Weissman, technical editor: Holy crap, you kicked my butt. Thanks for making my book dramatically better than it has ever been.

To LeeAnn Pickrell, copy editor: u made me write good, thx. To Michael Smyer, Total Seminars’ resident tech guru and photogra-

pher: Glad to see you staying focused. And your photos rocked as always! To Ford Pierson, graphics maven and editor: Superb conceptual art?

Check! Great editing? Check! Beating the boss in Unreal Tournament over and over again? Check, unfortunately.

To Aaron Verber, editor extraordinaire: Your quiet toils in the dark cor- ner of the office have once again paid outstanding dividends!

To Dudley Lehmer, my partner at Total Seminars: As always, thanks for keeping the ship afloat while I got to play on this book!

To Stephanie Evans, acquisitions coordinator at McGraw-Hill: You are my favorite South African ambassador since the Springboks. Thanks for keeping track of everything and (gently) smacking Scott when he forgot things.

To Molly Sharp and Jody McKenzie, project editors: It was a joy to work with you, Molly, and again with you, Jody. I couldn’t have asked for a better team! (Didn’t think I could resist making the pun, did you?)

To Andrea Fox, proofreader: You did a super job, thank you To Tom and Molly Sharp, compositors: The layout was excellent,

thanks!

To Staci Lynne ■■ Davis, vegan chef and

punk rocker: Thanks for showing me your world

and, in the process, expanding mine.

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Key Terms, identified in red, point out important vocabulary and definitions that you need to know.

Tech Tip sidebars provide inside information from experienced IT professionals.

Cross Check questions develop reasoning skills: ask, compare, contrast, and explain.

Engaging and Motivational— Using a conversational style and proven instructional approach, the author explains technical concepts in a clear, interesting way using real-world examples.

Makes Learning Fun!— Rich, colorful text and enhanced illustrations bring technical subjects to life.

10BaseT also introduced the networking world to the RJ-45 connector (Figure 4.9). Each pin on the RJ-45 connects to a single wire inside the cable; this enables de- vices to put voltage on the indi- vidual wires within the cable. The pins on the RJ-45 are numbered from 1 to 8, as shown in Figure 4.10.

The 10BaseT standard designates some of these numbered wires for specific purposes. As mentioned earlier, although the cable has four pairs, 10BaseT uses only two of the pairs. 10BaseT devices use pins 1 and 2 to send data, and pins 3 and 6 to receive data. Even though one pair of wires sends data and another receives data, a 10BaseT device cannot send and receive simul- taneously. The rules of CSMA/CD still apply: only one device can use the segment contained in the hub without causing a collision. Later versions of Ethernet will change this rule.

An RJ-45 connector is usually called a crimp, and the act (some folks call it an art) of installing a crimp onto the end of a piece of UTP cable is called crimping. The tool used to secure a crimp onto the end of a cable is a crimper. Each wire inside a UTP cable must connect to the proper pin inside the crimp. Manufacturers color-code each wire within a piece of four-pair UTP to assist in properly matching the ends. Each pair of wires consists of a solid- colored wire and a striped wire: blue/blue-white, orange/orange-white, brown/brown-white, and green/green-white (Figure 4.11).

The Telecommunications Industry Association/Electronics Industries Alliance (TIA/EIA) defines the industry standard for correct crimping of four-pair UTP for 10BaseT networks. Two standards currently exist: TIA/ EIA 568A and TIA/EIA 568B. Figure 4.12 shows the TIA/EIA 568A and TIA/ EIA 568B color-code standards. Note that the wire pairs used by 10BaseT (1 and 2; 3 and 6) come from the same color pairs (green/green-white and orange/orange-white). Following an established color-code scheme, such as TIA/EIA 568A, ensures that the wires match up correctly at each end of the cable.

66 Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks

Cross Check Check Your CATs!

You’ve already seen CAT levels in Chapter 3, “Cabling and Topology,” so check your memory and review the different speeds of the various CAT levels. Could 10BaseT use CAT 2? Could it use CAT 6? What types of devices can use CAT 1?

• Figure 4.9 Two views of an RJ-45 connector

• Figure 4.10 The pins on an RJ-45 connector are numbered 1 through 8.

• Figure 4.11 Color-coded pairs

The real name for RJ-45 is “8 Position 8 Contact (8P8C) modular plug.” The name RJ-45 is so dominant, however, that nobody but the nerdiest of nerds calls it by its real name. Stick to RJ-45.

AbouT ThIs book

Proven Learning Method Keeps You on Track Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks is structured to give you comprehensive knowledge of computer skills and technologies. The textbook’s active learning methodology guides you beyond mere recall and—through thought-provoking activities, labs, and sidebars—helps you develop critical-thinking, diagnostic, and communication skills.

Information technology (IT) offers many career paths, leading to occupations in such fields as PC repair, network administration, telecommunications, Web development, graphic design, and desktop support. To become competent in any IT field, however, you need

certain basic computer skills. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks builds a foundation for success in the IT field by introducing you to fundamental technology concepts and giving you essential computer skills.

Important Technology skills ■

66 Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks

Cross Check Check Your CATs!

• Figure 4.9 Two views of an RJ-45 connector

• Figure 4.10 The pins on an RJ-45 connector are numbered 1 through 8.

• Figure 4.11 Color-coded pairs

The real name for RJ-45 is “8 Position 8 Contact (8P8C) modular plug.” The name RJ-45 is so dominant, however, that nobody but the nerdiest of nerds calls it by its real name. Stick to RJ-45.

66 Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks

Cross Check Check Your CATs!

• Figure 4.9 Two views of an RJ-45 connector

• Figure 4.10 The pins on an RJ-45 connector are numbered 1 through 8.

• Figure 4.11 Color-coded pairs

The real name for RJ-45 is “8 Position 8 Contact (8P8C) modular plug.” The name RJ-45 is so dominant, however, that nobody but the nerdiest of nerds calls it by its real name. Stick to RJ-45.

/ Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / fm blind folio ix

consider that type of NIC. The spe- cific process by which a NIC uses electricity to send and receive data is exceedingly complicated, but luck- ily for you, not necessary to under- stand. Instead, just think of a charge on the wire as a one, and no charge as a zero. A chunk of data moving in pulses across a wire might look something like Figure 2.13.

If you put an oscilloscope on the wire to measure voltage, you’d see something like Figure 2.14. An oscilloscope is a powerful micro- scope that enables you to see elec- trical pulses.

Now, remembering that the pulses represent bi- nary data, visualize instead a string of ones and zeroes moving across the wire (Figure 2.15).

Once you understand how data moves along the wire, the next question becomes this: how does the net- work get the right data to the right system? All networks transmit data by breaking whatever is moving across the physical layer (files, print jobs, Web pages, and so forth) into discrete chunks called frames. A frame is basically a container for a chunk of data moving across a network. The NIC creates and sends, as well as receives and reads, these frames.

I like to visualize an imaginary table inside every NIC that acts as a frame creation and reading station. I see frames as those pneumatic canis- ters you see when you go to a drive-in teller at a bank. A little guy inside the network card—named Nick, naturally!—builds these pneumatic canisters (the frames) on the table, and then shoots them out on the wire to the hub (Figure 2.16).

Chapter 2: Building a Network with the OSI Model 15

Try This! What’s Your MAC Address?

You can readily determine your MAC address on a Windows computer from the command line. This works in all modern versions of Windows.

1. In Windows 2000/XP, click Start | Run. Enter the command CMD and press the ENTER key to get to a command prompt.

2. In Windows Vista, click Start, enter CMD in the Start Search text box, and press the ENTER key to get to a command prompt.

3. At the command prompt, type the command IPCONFIG /ALL and press the ENTER key.

• Figure 2.13 Data moving along a wire

• Figure 2.14 Oscilloscope of data

• Figure 2.15 Data as ones and zeroes

• Figure 2.16 Inside the NIC

A number of different frame types are used in different net- works. All NICs on the same net- work must use the same frame type or they will not be able to communicate with other NICs.

Each chapter includes Learning Objectives ■ that set measurable goals for chapter-by-chapter progress

Illustrations ■ that give you a clear picture of the technologies

Tutorials ■ that teach you to perform essential tasks and procedures hands-on

Try This!, Cross Check ■ , and Tech Tip sidebars that encourage you to practice and apply concepts in real-world settings

Notes, Tips ■ , and Warnings that guide you through difficult areas

Chapter Summaries ■ and Key Terms Lists that provide you with an easy way to review important concepts and vocabulary

Challenging End-of-Chapter Tests ■ that include vocabulary-building exercises, multiple-choice questions, essay questions, and on-the-job lab projects

This pedagogically rich book is designed to make learning easy and enjoyable and to help you develop the skills and critical-thinking abilities that will enable you to adapt to different job situations and troubleshoot problems.

Mike Meyers’ proven ability to explain concepts in a clear, direct, even humorous way makes this book interesting, motivational, and fun.

Effective Learning Tools ■

Try This! exercises apply core skills in a new setting.

Chapter Review sections provide concept summaries, key terms lists, and lots of questions and projects.

Key Terms Lists presents the important terms identified in the chapter.

Offers Practical Experience— Tutorials and lab assignments develop essential hands-on skills and put concepts in real-world contexts.

Robust Learning Tools— Summaries, key terms lists, quizzes, essay questions, and lab projects help you practice skills and measure progress.

Notes,Tips, and Warnings create a road map for success.

If you put an oscilloscope on the wire to measure voltage, you’d see something like Figure 2.14. An oscilloscope is a powerful micro- scope that enables you to see elec- trical pulses.

Now, remembering that the pulses represent bi- nary data, visualize instead a string of ones and zeroes moving across the wire (Figure 2.15).

Chapter 2: Building a Network with the OSI Model 15

Try This! What’s Your MAC Address?

You can readily determine your MAC address on a Windows computer from the command line. This works in all modern versions of Windows.

1. In Windows 2000/XP, click Start | Run. Enter the command CMD and press the ENTER key to get to a command prompt.

2. In Windows Vista, click Start, enter CMD in the Start Search text box, and press the ENTER key to get to a command prompt.

3. At the command prompt, type the command IPCONFIG /ALL and press the ENTER key.

• Figure 2.13 Data moving along a wire

• Figure 2.14 Oscilloscope of data

• Figure 2.15 Data as ones and zeroes

• Figure 2.16 Inside the NIC

A number of different frame types are used in different net- works. All NICs on the same net- work must use the same frame type or they will not be able to communicate with other NICs.

If you put an oscilloscope on the wire to measure voltage, you’d see something like Figure 2.14. An oscilloscope is a powerful micro- scope that enables you to see elec- trical pulses.

Now, remembering that the pulses represent bi- nary data, visualize instead a string of ones and zeroes moving across the wire (Figure 2.15).

Chapter 2: Building a Network with the OSI Model 15

Try This! What’s Your MAC Address?

You can readily determine your MAC address on a Windows computer from the command line. This works in all modern versions of Windows.

1. In Windows 2000/XP, click Start | Run. Enter the command CMD and press the ENTER key to get to a command prompt.

2. In Windows Vista, click Start, enter CMD in the Start Search text box, and press the ENTER key to get to a command prompt.

3. At the command prompt, type the command IPCONFIG /ALL and press the ENTER key.

• Figure 2.13 Data moving along a wire

• Figure 2.14 Oscilloscope of data

• Figure 2.15 Data as ones and zeroes

• Figure 2.16 Inside the NIC

A number of different frame types are used in different net- works. All NICs on the same net- work must use the same frame type or they will not be able to communicate with other NICs.

BaseTech

/ Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Front Matter

Contents at a Glance

CoNTENTs AT A GLANCE

Chapter 1 ■ CompTIA Network+ in a Nutshell 1

Chapter 2 ■ Network Models 8

Chapter 3 ■ Cabling and Topology 44

Chapter 4 ■ Ethernet Basics 66

Chapter 5 ■ Modern Ethernet 90

Chapter 6 ■ Installing a Physical Network 106

Chapter 7 ■ TCP/IP Basics 144

Chapter 8 ■ The Wonderful World of Routing 182

Chapter 9 ■ TCP/IP Applications 224

Chapter 10 ■ Network Naming 258

Chapter 11 ■ Securing TCP/IP 294

Chapter 12 ■ Advanced Networking Devices 330

Chapter 13 ■ IPv6 356

Chapter 14 ■ Remote Connectivity 380

Chapter 15 ■ Wireless Networking 424

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xi Contents at a Glance

Chapter 16 ■ Protecting Your Network 458

Chapter 17 ■ Virtualization 484

Chapter 18 ■ Network Management 504

Chapter 19 ■ Building a SOHO Network 534

Chapter 20 ■ Network Troubleshooting 554

Appendix A ■ Objectives Map: CompTIA Network+ 580

Appendix b ■ About the Download 592

■ Glossary 596

■ Index 632

xii

/ Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Front Matter

Contents

About the Author . . . . . . . . . . . . . . . . . . v Acknowledgments . . . . . . . . . . . . . . . . . .vii Preface. . . . . . . . . . . . . . . . . . . . . . . . xvii CompTIA Approved Quality Curriculum. . . . xix Instructor and Student Website. . . . . . . . . . xxv

Chapter 1 ■■CompTIA Network+ in a Nutshell 1 Who Needs CompTIA Network+?

I Just Want to Learn about Networks! . . . . . 1 What Is CompTIA Network+ Certification? . . . 1

What Is CompTIA? . . . . . . . . . . . . . . . 2 The Current CompTIA Network+

Certification Exam Release. . . . . . . . . . 2 How Do I Become CompTIA

Network+ Certified? . . . . . . . . . . . . . 2 What Is the Exam Like? . . . . . . . . . . . . . . . 3

How Do I Take the Test?. . . . . . . . . . . . . 4 How Much Does the Test Cost? . . . . . . . . . 4

How to Pass the CompTIA Network+ Exam . . . 5 Obligate Yourself . . . . . . . . . . . . . . . . 5 Set Aside the Right Amount of Study Time . . 5 Study for the Test . . . . . . . . . . . . . . . . 6

Chapter 2 ■■Network Models 8 Historical/Conceptual . . . . . . . . . . . . . . . 10 Working with Models . . . . . . . . . . . . . . . . 10

Biography of a Model . . . . . . . . . . . . . . 10 Network Models . . . . . . . . . . . . . . . . . 11

The OSI Seven-Layer Model in Action. . . . . . . 11 Welcome to MHTechEd!. . . . . . . . . . . . . 12

Test Specific. . . . . . . . . . . . . . . . . . . . . . 13 Let’s Get Physical—Network Hardware

and Layers 1–2 . . . . . . . . . . . . . . . . . . 13 The NIC . . . . . . . . . . . . . . . . . . . . . 15 The Two Aspects of NICs . . . . . . . . . . . . 21

Beyond the Single Wire—Network Software and Layers 3–7 . . . . . . . . . . . . . . . . . . 22

IP—Playing on Layer 3, the Network Layer . . . 24 Packets Within Frames . . . . . . . . . . . . . 25 Assembly and Disassembly—Layer 4,

the Transport Layer . . . . . . . . . . . . . 27

Talking on a Network—Layer 5, the Session Layer . . . . . . . . . . . . . . . 28

Standardized Formats, or Why Layer 6, Presentation, Has No Friends . . . . . . . . 30

Network Applications—Layer 7, the Application Layer . . . . . . . . . . . . . . 31

The TCP/IP Model. . . . . . . . . . . . . . . . . . 32 The Link Layer . . . . . . . . . . . . . . . . . 33 The Internet Layer. . . . . . . . . . . . . . . . 34 The Transport Layer . . . . . . . . . . . . . . . 34 The Application Layer . . . . . . . . . . . . . . 36 Frames, Packets, and Segments, Oh My! . . . . 37 The Tech’s Troubleshooting Tool . . . . . . . . . 38

Chapter 2 Review . . . . . . . . . . . . . . . . . . 39

Chapter 3 ■■Cabling and Topology 44 Test Specific. . . . . . . . . . . . . . . . . . . . . . 45 Topology . . . . . . . . . . . . . . . . . . . . . . . 45

Bus and Ring . . . . . . . . . . . . . . . . . . 45 Star . . . . . . . . . . . . . . . . . . . . . . . 46 Hybrids . . . . . . . . . . . . . . . . . . . . . 47 Mesh and Point-to-Multipoint . . . . . . . . . 47 Point-to-Point . . . . . . . . . . . . . . . . . . 50 Parameters of a Topology . . . . . . . . . . . . 50

Cabling . . . . . . . . . . . . . . . . . . . . . . . . 50 Coaxial Cable . . . . . . . . . . . . . . . . . . 50 Twisted Pair . . . . . . . . . . . . . . . . . . . 53 Fiber-Optic . . . . . . . . . . . . . . . . . . . 55 Other Cables . . . . . . . . . . . . . . . . . . . 56 Fire Ratings . . . . . . . . . . . . . . . . . . . 58

Networking Industry Standards—IEEE . . . . . . 58 Chapter 3 Review . . . . . . . . . . . . . . . . . . 60

Chapter 4 ■■Ethernet Basics 66 Historical/Conceptual . . . . . . . . . . . . . . . 67 Ethernet . . . . . . . . . . . . . . . . . . . . . . . . 67

Topology . . . . . . . . . . . . . . . . . . . . . 67 Test Specific. . . . . . . . . . . . . . . . . . . . . . 68 Organizing the Data: Ethernet Frames . . . . . . 68

CSMA/CD . . . . . . . . . . . . . . . . . . . 71

CoNTENTs

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xiii Contents

Early Ethernet Networks . . . . . . . . . . . . . . 73 10BaseT . . . . . . . . . . . . . . . . . . . . . 73 10BaseFL . . . . . . . . . . . . . . . . . . . . 76

Extending and Enhancing Ethernet Networks . . 78 Connecting Ethernet Segments . . . . . . . . . 78 Switched Ethernet . . . . . . . . . . . . . . . . 80 Troubleshooting Hubs and Switches . . . . . . 84

Chapter 4 Review . . . . . . . . . . . . . . . . . . 85

Chapter 5 ■■Modern Ethernet 90 Test Specific. . . . . . . . . . . . . . . . . . . . . . 91 100-Megabit Ethernet . . . . . . . . . . . . . . . . 91

100BaseT . . . . . . . . . . . . . . . . . . . . 91 100BaseFX . . . . . . . . . . . . . . . . . . . 93

Gigabit Ethernet . . . . . . . . . . . . . . . . . . . 94 1000BaseCX . . . . . . . . . . . . . . . . . . . 95 1000BaseSX . . . . . . . . . . . . . . . . . . . 95 1000BaseLX . . . . . . . . . . . . . . . . . . . 95 New Fiber Connectors. . . . . . . . . . . . . . 95 Implementing Multiple Types of Gigabit

Ethernet . . . . . . . . . . . . . . . . . . . 96 10 Gigabit Ethernet . . . . . . . . . . . . . . . . . 97

Fiber-based 10 GbE . . . . . . . . . . . . . . . 97 Copper-based 10 GbE . . . . . . . . . . . . . . 98 10 GbE Physical Connections . . . . . . . . . . 99 Backbones . . . . . . . . . . . . . . . . . . . . 99 Know Your Ethernets!. . . . . . . . . . . . . 100

Chapter 5 Review . . . . . . . . . . . . . . . . . 101

Chapter 6 ■■Installing a Physical Network 106 Historical/Conceptual . . . . . . . . . . . . . . 107 Understanding Structured Cabling . . . . . . . 107

Cable Basics—A Star Is Born . . . . . . . . . 108 Test Specific. . . . . . . . . . . . . . . . . . . . . 109

Structured Cable Network Components . . . 109 Structured Cable—Beyond the Star. . . . . . 116

Installing Structured Cabling . . . . . . . . . . . 119 Getting a Floor Plan. . . . . . . . . . . . . . 119 Mapping the Runs . . . . . . . . . . . . . . 119 Determining the Location of the

Telecommunications Room . . . . . . . . . 120 Pulling Cable . . . . . . . . . . . . . . . . . 121 Making Connections . . . . . . . . . . . . . 123 Testing the Cable Runs . . . . . . . . . . . . 126

NICs . . . . . . . . . . . . . . . . . . . . . . . . . 130 Buying NICs . . . . . . . . . . . . . . . . . 131 Link Lights . . . . . . . . . . . . . . . . . . 133

Diagnostics and Repair of Physical Cabling . . 134 Diagnosing Physical Problems . . . . . . . . 134 Check Your Lights . . . . . . . . . . . . . . . 135 Check the NIC . . . . . . . . . . . . . . . . . 135 Cable Testing . . . . . . . . . . . . . . . . . 136 Problems in the Telecommunications Room . . 136 Toners . . . . . . . . . . . . . . . . . . . . . 137

Chapter 6 Review . . . . . . . . . . . . . . . . . 139

Chapter 7 ■■TCP/IP Basics 144 Historical/Conceptual . . . . . . . . . . . . . . 145 Standardizing Networking Technology . . . . . 145 Test Specific. . . . . . . . . . . . . . . . . . . . . 146 The TCP/IP Protocol Suite . . . . . . . . . . . . 146

Internet Layer Protocols. . . . . . . . . . . . 146 Transport Layer Protocols . . . . . . . . . . . 147 Application Layer Protocols . . . . . . . . . . 149

IP in Depth . . . . . . . . . . . . . . . . . . . . . 150 IP Addresses . . . . . . . . . . . . . . . . . . 151 IP Addresses in Action . . . . . . . . . . . . 155 Class IDs . . . . . . . . . . . . . . . . . . . 162

CIDR and Subnetting . . . . . . . . . . . . . . . 163 Subnetting . . . . . . . . . . . . . . . . . . . 164 CIDR: Subnetting in the Real World . . . . . 169

Using IP Addresses . . . . . . . . . . . . . . . . 170 Static IP Addressing . . . . . . . . . . . . . 170 Dynamic IP Addressing. . . . . . . . . . . . 173 Special IP Addresses. . . . . . . . . . . . . . 176

Chapter 7 Review . . . . . . . . . . . . . . . . . 177

Chapter 8 ■■The Wonderful World of Routing 182 Historical/Conceptual . . . . . . . . . . . . . . 183 How Routers Work . . . . . . . . . . . . . . . . 183 Test Specific. . . . . . . . . . . . . . . . . . . . . 184

Routing Tables. . . . . . . . . . . . . . . . . 184 Freedom from Layer 2 . . . . . . . . . . . . . 191 Network Address Translation . . . . . . . . . 191

Dynamic Routing . . . . . . . . . . . . . . . . . 196 Routing Metrics . . . . . . . . . . . . . . . . 198 Distance Vector . . . . . . . . . . . . . . . . 199 Link State . . . . . . . . . . . . . . . . . . . 204 EIGRP—the Lone Hybrid . . . . . . . . . . . 208 Dynamic Routing Makes the Internet . . . . 209

Working with Routers . . . . . . . . . . . . . . . 209 Connecting to Routers . . . . . . . . . . . . 210 Basic Router Configuration . . . . . . . . . . 215 Router Problems . . . . . . . . . . . . . . . . 216

Chapter 8 Review . . . . . . . . . . . . . . . . . 219

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Contents

Chapter 9 ■■TCP/IP Applications 224 Historical/Conceptual . . . . . . . . . . . . . . 225 Transport Layer and Network Layer

Protocols . . . . . . . . . . . . . . . . . . . . . 225 How People Communicate . . . . . . . . . . 225

Test Specific. . . . . . . . . . . . . . . . . . . . . 225 TCP . . . . . . . . . . . . . . . . . . . . . . 225 UDP . . . . . . . . . . . . . . . . . . . . . . 226 ICMP . . . . . . . . . . . . . . . . . . . . . 227 IGMP . . . . . . . . . . . . . . . . . . . . . 227

The Power of Port Numbers . . . . . . . . . . . 228 Registered Ports . . . . . . . . . . . . . . . . 230 Connection Status . . . . . . . . . . . . . . . 232 Rules for Determining Good vs.

Bad Communications . . . . . . . . . . . 236 Common TCP/IP Applications. . . . . . . . . . 236

The World Wide Web . . . . . . . . . . . . . 236 Telnet . . . . . . . . . . . . . . . . . . . . . 242 E-mail . . . . . . . . . . . . . . . . . . . . . 246 FTP . . . . . . . . . . . . . . . . . . . . . . 249 Internet Applications . . . . . . . . . . . . . 252

Chapter 9 Review . . . . . . . . . . . . . . . . . 253

Chapter 10 ■■Network Naming 258 Historical/Conceptual . . . . . . . . . . . . . . 259 DNS . . . . . . . . . . . . . . . . . . . . . . . . . 259 Test Specific. . . . . . . . . . . . . . . . . . . . . 260

How DNS Works . . . . . . . . . . . . . . . 260 Name Spaces. . . . . . . . . . . . . . . . . . 262 DNS Servers . . . . . . . . . . . . . . . . . 272 Troubleshooting DNS . . . . . . . . . . . . . 279

WINS . . . . . . . . . . . . . . . . . . . . . . . . 282 Configuring WINS Clients . . . . . . . . . . 283 Troubleshooting WINS . . . . . . . . . . . . 284

Diagnosing TCP/IP Networks . . . . . . . . . . 284 Chapter 10 Review. . . . . . . . . . . . . . . . . 288

Chapter 11 ■■Securing TCP/IP 294 Test Specific. . . . . . . . . . . . . . . . . . . . . 295 Making TCP/IP Secure . . . . . . . . . . . . . . 295

Encryption. . . . . . . . . . . . . . . . . . . 295 Nonrepudiation . . . . . . . . . . . . . . . . 302 Authentication . . . . . . . . . . . . . . . . 307 Authorization . . . . . . . . . . . . . . . . . 307

TCP/IP Security Standards . . . . . . . . . . . . 308 Authentication Standards . . . . . . . . . . . 308 Encryption Standards . . . . . . . . . . . . . 316 Combining Authentication and Encryption . . 319

Secure TCP/IP Applications . . . . . . . . . . . 320 HTTPS . . . . . . . . . . . . . . . . . . . . 321 SCP . . . . . . . . . . . . . . . . . . . . . . 321 SFTP. . . . . . . . . . . . . . . . . . . . . . 322 SNMP . . . . . . . . . . . . . . . . . . . . . 322 LDAP . . . . . . . . . . . . . . . . . . . . . 323 NTP . . . . . . . . . . . . . . . . . . . . . . 323

Chapter 11 Review . . . . . . . . . . . . . . . . . 324

Chapter 12 ■■Advanced Networking Devices 330 Client/Server and Peer-to-Peer Topologies . . . 331 Historical/Conceptual . . . . . . . . . . . . . . 331

Client/Server . . . . . . . . . . . . . . . . . 331 Peer-to-Peer . . . . . . . . . . . . . . . . . . 332

Test Specific. . . . . . . . . . . . . . . . . . . . . 333 Client/Server and Peer-to-Peer Today. . . . . 333

Virtual Private Networks . . . . . . . . . . . . . 334 PPTP VPNs . . . . . . . . . . . . . . . . . . 335 L2TP VPNs . . . . . . . . . . . . . . . . . . 336 SSL VPNs . . . . . . . . . . . . . . . . . . . 337

Virtual LANs . . . . . . . . . . . . . . . . . . . . 337 Trunking. . . . . . . . . . . . . . . . . . . . 338 Configuring a VLAN-capable Switch. . . . . 339 Virtual Trunk Protocol . . . . . . . . . . . . 341 InterVLAN Routing . . . . . . . . . . . . . 341

Multilayer Switches . . . . . . . . . . . . . . . . 342 Load Balancing . . . . . . . . . . . . . . . . 343 QoS and Traffic Shaping . . . . . . . . . . . 345 Network Protection . . . . . . . . . . . . . . 346

Chapter 12 Review. . . . . . . . . . . . . . . . . 351

Chapter 13 ■■IPv6 356 Test Specific. . . . . . . . . . . . . . . . . . . . . 357 IPv6 Basics . . . . . . . . . . . . . . . . . . . . . 357

IPv6 Address Notation . . . . . . . . . . . . 357 Link-Local Address . . . . . . . . . . . . . . 359 IPv6 Subnet Masks . . . . . . . . . . . . . . 360 The End of Broadcast . . . . . . . . . . . . . 361 Global Address . . . . . . . . . . . . . . . . 363 Aggregation . . . . . . . . . . . . . . . . . . 364

Using IPv6 . . . . . . . . . . . . . . . . . . . . . 366 Enabling IPv6 . . . . . . . . . . . . . . . . . 367 NAT in IPv6. . . . . . . . . . . . . . . . . . 368 DHCP in IPv6 . . . . . . . . . . . . . . . . 369 DNS in IPv6 . . . . . . . . . . . . . . . . . 370

Moving to IPv6 . . . . . . . . . . . . . . . . . . . 371 IPv4 and IPv6 . . . . . . . . . . . . . . . . . 372 Tunnels . . . . . . . . . . . . . . . . . . . . 372 IPv6 Is Here, Really! . . . . . . . . . . . . . 375

Chapter 13 Review. . . . . . . . . . . . . . . . . 376

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Chapter 14 ■■Remote Connectivity 380 Historical/Conceptual . . . . . . . . . . . . . . 381 Telephony and Beyond . . . . . . . . . . . . . . 381

The Dawn of Long Distance. . . . . . . . . . 382 Test Specific. . . . . . . . . . . . . . . . . . . . . 386

Digital Telephony . . . . . . . . . . . . . . . 386 Copper Carriers: T1 and T3 . . . . . . . . . . 387 Fiber Carriers: SONET/SDH and OC . . . . 391 Packet Switching . . . . . . . . . . . . . . . 392 Real-World WAN . . . . . . . . . . . . . . . 395 Alternative to Telephony WAN . . . . . . . . 396

The Last Mile . . . . . . . . . . . . . . . . . . . . 397 Dial-Up . . . . . . . . . . . . . . . . . . . . 397 DSL . . . . . . . . . . . . . . . . . . . . . . 401 Cable Modems . . . . . . . . . . . . . . . . . 404 Satellite . . . . . . . . . . . . . . . . . . . . 406 Cellular WAN . . . . . . . . . . . . . . . . . 406 Fiber . . . . . . . . . . . . . . . . . . . . . . 407 BPL . . . . . . . . . . . . . . . . . . . . . . 407 Which Connection? . . . . . . . . . . . . . . 408

Using Remote Access . . . . . . . . . . . . . . . 408 Dial-Up to the Internet . . . . . . . . . . . . 409 Private Dial-Up . . . . . . . . . . . . . . . . 410 VPNs . . . . . . . . . . . . . . . . . . . . . 411 Dedicated Connection . . . . . . . . . . . . . 411 Remote Terminal . . . . . . . . . . . . . . . 413

Chapter 14 Review. . . . . . . . . . . . . . . . . 417

Chapter 15 ■■Wireless Networking 424 Historical/Conceptual . . . . . . . . . . . . . . 425 Test Specific. . . . . . . . . . . . . . . . . . . . . 425 Wi-Fi Standards . . . . . . . . . . . . . . . . . . 425

802.11 . . . . . . . . . . . . . . . . . . . . . 425 802.11b . . . . . . . . . . . . . . . . . . . . 432 802.11a . . . . . . . . . . . . . . . . . . . . 432 802.11g . . . . . . . . . . . . . . . . . . . . 433 802.11n . . . . . . . . . . . . . . . . . . . . 433 Wireless Networking Security . . . . . . . . 434 Power over Ethernet. . . . . . . . . . . . . . 437

Implementing Wi-Fi . . . . . . . . . . . . . . . . 437 Performing a Site Survey . . . . . . . . . . . 438 Installing the Client . . . . . . . . . . . . . . 439 Setting Up an Ad Hoc Network. . . . . . . . 439 Setting Up an Infrastructure Network . . . . 439 Extending the Network . . . . . . . . . . . . 446 Verify the Installation . . . . . . . . . . . . . 448

Troubleshooting Wi-Fi . . . . . . . . . . . . . . . 448 Hardware Troubleshooting . . . . . . . . . . 448 Software Troubleshooting . . . . . . . . . . . 449

Connectivity Troubleshooting . . . . . . . . . 449 Configuration Troubleshooting . . . . . . . . 450

Chapter 15 Review. . . . . . . . . . . . . . . . . 452

Chapter 16 ■■Protecting Your Network 458 Test Specific. . . . . . . . . . . . . . . . . . . . . 459 Common Threats. . . . . . . . . . . . . . . . . . 459

System Crash/Hardware Failure . . . . . . . 459 Administrative Access Control . . . . . . . . 459 Malware . . . . . . . . . . . . . . . . . . . . 460 Social Engineering . . . . . . . . . . . . . . 462 Man in the Middle . . . . . . . . . . . . . . 463 Denial of Service. . . . . . . . . . . . . . . . 463 Physical Intrusion . . . . . . . . . . . . . . . 464 Attacks on Wireless Connections . . . . . . . 465

Securing User Accounts . . . . . . . . . . . . . . 466 Authentication . . . . . . . . . . . . . . . . 466 Passwords . . . . . . . . . . . . . . . . . . . 467 Controlling User Accounts . . . . . . . . . . 468

Firewalls . . . . . . . . . . . . . . . . . . . . . . 470 Hiding the IPs . . . . . . . . . . . . . . . . . 471 Port Filtering . . . . . . . . . . . . . . . . . 471 Packet Filtering . . . . . . . . . . . . . . . . 473 MAC Filtering . . . . . . . . . . . . . . . . 474 Personal Firewalls . . . . . . . . . . . . . . . 474 Network Zones . . . . . . . . . . . . . . . . 476 Vulnerability Scanners . . . . . . . . . . . . 477

Chapter 16 Review. . . . . . . . . . . . . . . . . 478

Chapter 17 ■■Virtualization 484 Historical/Conceptual . . . . . . . . . . . . . . 485 What Is Virtualization? . . . . . . . . . . . . . . 485

Meet the Hypervisor. . . . . . . . . . . . . . 486 Emulation vs. Virtualization . . . . . . . . . 486 Sample Virtualization . . . . . . . . . . . . . 488

Test Specific. . . . . . . . . . . . . . . . . . . . . 492 Why Do We Virtualize? . . . . . . . . . . . . . . 492

Power Saving . . . . . . . . . . . . . . . . . 492 Hardware Consolidation . . . . . . . . . . . 493 System Recovery . . . . . . . . . . . . . . . 493 System Duplication . . . . . . . . . . . . . . 494 Research . . . . . . . . . . . . . . . . . . . . 494

Virtualization in Modern Networks . . . . . . . 494 Virtual Machine Managers . . . . . . . . . . 496 Hypervisors . . . . . . . . . . . . . . . . . . 497 Virtual Switches . . . . . . . . . . . . . . . 498 Virtual PBX . . . . . . . . . . . . . . . . . . 499 Network as a Service . . . . . . . . . . . . . 499

Chapter 17 Review. . . . . . . . . . . . . . . . . 500

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Chapter 18 ■■Network Management 504 Test Specific. . . . . . . . . . . . . . . . . . . . . 505 Network Configuration Management . . . . . . 505

Configuration Management Documentation . . 505 Change Management Documentation . . . . 511

Monitoring Performance and Connectivity . . . 512 Performance Monitor . . . . . . . . . . . . . 512 Logs and Network Traffic . . . . . . . . . . . 518

Network Performance Optimization . . . . . . 519 Caching . . . . . . . . . . . . . . . . . . . . 520 Controlling Data Throughput. . . . . . . . . 520 Keeping Resources Available . . . . . . . . . 522

Chapter 18 Review. . . . . . . . . . . . . . . . . 528

Chapter 19 ■■Building a SOHO Network 534 Historical/Conceptual . . . . . . . . . . . . . . 535 Test Specific. . . . . . . . . . . . . . . . . . . . . 535 Designing a SOHO Network . . . . . . . . . . . 535 Building the Network . . . . . . . . . . . . . . . 536

Define the Network Needs. . . . . . . . . . . 536 Network Design . . . . . . . . . . . . . . . . 537 Compatibility Issues . . . . . . . . . . . . . . 539 Internal Connections . . . . . . . . . . . . . 540 External Connections . . . . . . . . . . . . . 544 ISPs and MTUs . . . . . . . . . . . . . . . . 546 Peripherals. . . . . . . . . . . . . . . . . . . 548

Security . . . . . . . . . . . . . . . . . . . . . . . 549 Chapter 19 Review. . . . . . . . . . . . . . . . . 550

Chapter 20 ■■Network Troubleshooting 554 Test Specific. . . . . . . . . . . . . . . . . . . . . 555 Troubleshooting Tools . . . . . . . . . . . . . . . 555

Hardware Tools . . . . . . . . . . . . . . . . 555 Software Tools . . . . . . . . . . . . . . . . . 558

The Troubleshooting Process . . . . . . . . . . . 564 Identify the Problem . . . . . . . . . . . . . . 565 Establish a Theory of Probable Cause . . . . . 567

Test the Theory to Determine Cause . . . . . 567 Establish a Plan of Action and Identify

Potential Effects . . . . . . . . . . . . . . 568 Implement and Test the Solution or

Escalate as Necessary . . . . . . . . . . . 568 Verify Full System Functionality and

Implement Preventative Measures . . . . . 569 Document Findings, Actions, and

Outcomes . . . . . . . . . . . . . . . . . . 569 Troubleshooting Scenarios . . . . . . . . . . . . 569

“I Can’t Log In!” . . . . . . . . . . . . . . . 570 “I Can’t Get to This Web Site!” . . . . . . . . 570 “Our Web Server Is Sluggish!” . . . . . . . . 571 “I Can’t See Anything on the Network!” . . . 571 “It’s Time to Escalate!” . . . . . . . . . . . . 572 Troubleshooting Is Fun! . . . . . . . . . . . . 574

Chapter 20 Review. . . . . . . . . . . . . . . . . 575

Appendix A ■■Objectives Map: CompTIA

Network+ 580

Appendix B ■■About the Download 592

System Requirements . . . . . . . . . . . . . . . 592 Installing and Running Total Tester . . . . . . . 592 About Total Tester 593

Mike Meyers' Video Training 593 Mike’s Cool Tools . . . . . . . . . . . . . . . . . 594

Boson’s NetSim Network Simulator . . . . . . . 594 Technical Support . . . . . . . . . . . . . . . . . 595

Boson Technical Support . . . . . . . . . . . 595

■■Glossary 596

■■Index 632

. . . . . . . . . . . . . . . . . Playing Mike Meyers' Videos 593 . . . . . . . . . .

. . . . . . . . . .

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xvii Preface

I was a teacher long before I was ever an author. I started writing computer books for the simple reason that no one wrote the kind of books I wanted to read. The books were either too simple (Chapter 1, “Using Your Mouse”) or too complex (Chapter 1, “TTL Logic and Transistors”) and none of them provided a motivation for me to learn the information. I guessed that there were geeky readers just like me who wanted to know why they needed to know the information in a computer book.

Good books motivate the reader to learn what he or she is reading. If a book discusses binary arithmetic but doesn’t explain why I need to learn it, for example, that’s not a good book. Tell me that understanding binary makes it easier to understand how an IP address works or why we’re about to run out of IP addresses and how IPv6 can help, then I get excited, no mat- ter how geeky the topic. If I don’t have a good reason, a good motivation to do something, then I’m simply not going to do it (which explains why I haven’t jumped out of an airplane!).

In this book, I teach you why you need to understand the wide world of networking. You’ll learn everything you need to start building, configuring, and supporting networks. In the process, you’ll gain the knowledge you need to pass the CompTIA Network+ certification exam.

Enjoy, my fellow geek.

PrEfACE

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xix CompTIA Approved Quality Curriculum

CompTIA APProvEd QuALITy CurrICuLuM

CompTIA Network+■■ The CompTIA Network+ certification ensures that the successful candidate has the important knowledge and skills necessary to manage, maintain, troubleshoot, install, operate, and configure basic network infrastructure; describe networking technologies; basic design principles; and adhere to wiring standards and use testing tools.

It Pays to Get Certified■■ In a digital world, digital literacy is an essential survival skill. Certification proves you have the knowledge and skill to solve business problems in virtually any business environment. Certifications are highly valued cre- dentials that qualify you for jobs, increased compensation, and promotion.

CompTIA Network+ certification is held by many IT staffers across many organizations. 21% of IT staff within a random sampling of U.S. orga- nizations within a cross section of industry verticals hold CompTIA Net- work+ certification.

The CompTIA Network+ credential—proves knowledge of ■ networking features and functions and is the leading vendor-neutral certification for networking professionals.

Starting salary—the average starting salary of network engineers can ■ be up to $70,000.

Career pathway—CompTIA Network+ is the first step in starting a ■ networking career, and is recognized by Microsoft as part of their MS program. Other corporations, such as Novell, Cisco, and HP also recognize CompTIA Network+ as part of their certification tracks.

More than 325,000 individuals worldwide are CompTIA Network+ ■ certified.

Mandated/recommended by organizations worldwide—Apple, ■ Cisco, HP, Ricoh, the U.S. State Department, and U.S. government contractors such as EDS, General Dynamics, and Northrop Grumman recommend or mandate CompTIA Network+.

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/ Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Front Matter

CompTIA Approved Quality Curriculum

How Certification Helps Your Career

CompTIA Career Pathway CompTIA offers a number of credentials that form a foundation for your career in technology and that allow you to pursue specific areas of concentration. Depend- ing on the path you choose, CompTIA certifications help you build upon your skills and knowledge, supporting learning throughout your career.

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xxi CompTIA Approved Quality Curriculum

Steps to Getting Certified and ■■ Staying Certified

Review exam objectives.1. Review the certification objectives to make sure you know what is covered in the exam: www.comptia.org/certifications/testprep/examobjectives.aspx

Practice for the exam.2. After you have studied for the certification, take a free assessment and sample test to get an idea what type of questions might be on the exam: www.comptia.org/certifications/testprep/practicetests.aspx

Purchase an exam voucher.3. Purchase exam vouchers on the CompTIA Marketplace, which is located at: www.comptiastore.com

Take the test!4. Select a certification exam provider, and schedule a time to take your exam. You can find exam providers at the following link: www.comptia.org/certifications/testprep/testingcenters.aspx

Stay certified!5. Continuing education is required. Effective January 1, 2011, CompTIA Network+ certifications are valid for three years from the date of certification. There are a number of ways the certification can be renewed. For more information go to: http:// certification.comptia.org/getCertified/steps_to_certification/ stayCertified.aspx

Join the Professional Community■■ The free online IT Pro Community provides valuable content to students and professionals. Join the IT Pro Community:

http://itpro.comptia.org

Career IT job resources include:

Where to start in IT ■

Career assessments ■

Salary trends ■

U.S. job board ■

Join the IT Pro Community and get access to:

Forums on networking, security, computing, and cutting-edge ■ technologies

Access to blogs written by industry experts ■

www.comptia.org/certifications/testprep/examobjectives.aspx
www.comptia.org/certifications/testprep/practicetests.aspx
www.comptiastore.com
www.comptia.org/certifications/testprep/testingcenters.aspx
http://certification.comptia.org/getCertified/steps_to_certification/stayCertified.aspx
http://certification.comptia.org/getCertified/steps_to_certification/stayCertified.aspx
http://certification.comptia.org/getCertified/steps_to_certification/stayCertified.aspx
http://itpro.comptia.org
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CompTIA Approved Quality Curriculum

Current information on cutting edge technologies ■

Access to various industry resource links and articles related to IT ■ and IT careers

APPRO V E D Q U A L I T Y C O

N T EN

T Content Seal of Quality■■

This courseware bears the seal of CompTIA Approved Quality Content. This seal signifies this content covers 100 percent of the exam objectives and implements important instructional design principles. CompTIA rec- ommends multiple learning tools to help increase coverage of the learning objectives.

Why CompTIA?■■ Global recognition ■ CompTIA is recognized globally as the leading IT nonprofit trade association and has enormous credibility. Plus, CompTIA’s certifications are vendor-neutral and offer proof of foundational knowledge that translates across technologies.

Valued by hiring managers ■ Hiring managers value CompTIA certification because it is vendor- and technology-independent validation of your technical skills.

Recommended or required by government and businesses ■ Many government organizations and corporations (for example, Dell, Sharp, Ricoh, the U.S. Department of Defense, and many more) either recommend or require technical staff to be CompTIA certified.

Three CompTIA certifications ranked in the top 10 ■ In a study by DICE of 17,000 technology professionals, certifications helped command higher salaries at all experience levels.

BaseTech

CompTIA Approved Quality Curriculum

How to Obtain More Information■■ Visit CompTIA online ■ Go to www.comptia.org to learn more about getting CompTIA certified.

Contact CompTIA ■ Please call 866-835-8020, ext. 5 or e-mail questions@comptia.org.

Join the IT Pro Community ■ Go to http://itpro.comptia.org to join the IT community to get relevant career information.

Connect with CompTIA ■ Find us on Facebook, LinkedIn, Twitter, and YouTube.

CAQC Disclaimer■■ The logo of the CompTIA Approved Quality Curriculum (CAQC) program and the status of this or other training material as “Approved” under the CompTIA Approved Quality Curriculum program signifies that, in Comp- TIA’s opinion, such training material covers the content of CompTIA’s related certification exam.

The contents of this training material were created for the CompTIA Network+ exam covering CompTIA certification objectives that were cur- rent as of the date of publication.

CompTIA has not reviewed or approved the accuracy of the contents of this training material and specifically disclaims any warranties of mer- chantability or fitness for a particular purpose. CompTIA makes no guaran- tee concerning the success of persons using any such “Approved” or other training material in order to prepare for any CompTIA certification exam.

xxiii

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Instructor and Student Web Site

INsTruCTor ANd sTudENT WEb sITE

For instructor and student resources, please visit:

www.meyersnetplus.com

Students will find chapter quizzes that will help them learn more about troubleshooting and fixing networks, and teachers can access the support materials outlined below.

Additional Resources for Teachers■■ McGraw-Hill Connect, a Web-based learning platform, connects instructors with their support materials and students with chapter assessments. The Connect Online Learning Center provides resources for teachers in a format that follows the organization of the textbook.

This site includes the following:

Answer keys to the end-of-chapter activities in the textbook ■

Instructor’s Manual that contains learning objectives, classroom ■ preparation notes, instructor tips, and a lecture outline for each chapter

Answer keys to the Mike Meyers’ Lab Manual activities (available ■ separately)

Access to test bank files and software that allow you to generate ■ a wide array of paper- or network-based tests, and that feature automatic grading. The test bank includes:

Hundreds of practice questions and a wide variety of question ■ types categorized by exam objective, enabling you to customize each test to maximize student progress

Test bank files available on EZ Test Online and as downloads ■ from the Online Learning Center in these formats: Blackboard, Web CT, EZ Test, and Word

Engaging PowerPoint slides on the lecture topics that include full- ■ color artwork from the book

Please contact your McGraw-Hill sales representative for details.

xxv

BaseTech

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1 chapter

/ Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Chapter 1

“Networking is an essential part

of building wealth.”

—Armstrong WilliAms

CompTIA Network+ in a Nutshell

In this chapter, you will learn how to

Describe the importance of ■■ CompTIA Network+ certification

Illustrate the structure and ■■ contents of the CompTIA Network+ certification exam

Plan a strategy to prepare for ■■ the exam

By picking up this book, you’ve shown an interest in learning about networking. But be forewarned. The term networking describes a vast field of study, far too large for any single certification, book, or training course to

cover. Do you want to configure routers and switches for a living? Do you want

to administer a large Windows network at a company? Do you want to install

wide area network connections? Do you want to set up Web servers? Do you

want to secure networks against attacks?

If you’re considering a CompTIA Network+ certification, you probably don’t

yet know exactly what aspect of networking you want to pursue, and that’s

okay! You’re going to love preparing for the CompTIA Network+ certification.

Attaining CompTIA Network+ certification provides you with three

fantastic benefits. First, you get a superb overview of networking that helps

you decide what part of the industry you’d like to pursue. Second, it acts as

a prerequisite toward other, more advanced certifications. Third, the amount

of eye-opening information you’ll gain just makes getting CompTIA Network+

certified plain old fun.

1 chapter

BaseTech / Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Chapter 1

Chapter 1: CompTIA Network+ in a Nutshell 1

CompTIA Network+ in a Nutshell

Nothing comes close to providing a better overview of networking than CompTIA Network+. The certification covers local area networks (LANs), wide area networks (WANs), the Internet, security, cabling, and applica- tions in a wide-but-not-too-deep fashion that showcases the many different parts of a network and hopefully tempts you to investigate the aspects that intrigue you by looking into follow-up certifications.

The process of attaining CompTIA Network+ certification will give you a solid foundation in the whole field of networking. Mastering the compe- tencies will help fill in gaps in your knowledge and provide an ongoing series of “a-ha!” moments of grasping the big picture that make being a tech so much fun.

Ready to learn a lot, grab a great certification, and have fun doing it? Then welcome to CompTIA Network+ certification!

Who Needs CompTIA Network+? ■■ I Just Want to Learn about Networks!

Whoa up there, amigo! Are you one of those folks who either has never heard of the CompTIA Network+ exam or just doesn’t have any real inter- est in certification? Is your goal only to get a solid handle on the idea of networking and a jump start on the basics? Are you looking for that “magic bullet” book that you can read from beginning to end and then start install- ing and troubleshooting a network? Do you want to know what’s involved with running network cabling in your walls or getting your new wireless network working? Are you tired of not knowing enough about what TCP/ IP is and how it works? If these types of questions are running through your mind, then rest easy—you have the right book. Like every book with the Mike Meyers name, you’ll get solid concepts without pedantic details or broad, meaningless overviews. You’ll look at real-world networking as performed by real techs. This is a book that understands your needs and goes well beyond the scope of a single certification.

If the CompTIA Network+ exam isn’t for you, you can skip the rest of this chapter, shift your brain into learn mode, and dive into Chapter 2. But then, if you’re going to have the knowledge, why not get the certification?

What Is CompTIA Network+ ■■ Certification?

CompTIA Network+ certification is an industry-wide, vendor-neutral certi- fication program developed and sponsored by the Computing Technology Industry Association (CompTIA). The CompTIA Network+ certification shows that you have a basic competency in the physical support of net- working systems and knowledge of the conceptual aspects of networking.

Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks 2

/ Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Chapter 1

To date, many hundreds of thousands of technicians have become CompTIA Network+ certified.

CompTIA Network+ certification enjoys wide recognition throughout the IT industry. At first, it rode in on the coattails of the successful CompTIA A+ certification program, but it now stands on its own in the network- ing industry and is considered the obvious next step after CompTIA A+ certification.

What Is CompTIA? CompTIA is a nonprofit, industry trade association based in Oakbrook Ter- race, Illinois, on the outskirts of Chicago. Tens of thousands of computer resellers, value-added resellers, distributors, manufacturers, and training companies from all over the world are members of CompTIA.

CompTIA was founded in 1982. The following year, CompTIA began offering the CompTIA A+ certification exam. CompTIA A+ certification is now widely recognized as a de facto requirement for entrance into the PC industry. Because the CompTIA A+ exam covers networking only lightly, CompTIA decided to establish a vendor-neutral test covering basic net- working skills. So, in April 1999, CompTIA unveiled the CompTIA Net- work+ certification exam.

CompTIA provides certifications for a variety of areas in the computer industry, offers opportunities for its members to interact, and represents its members’ interests to government bodies. CompTIA certifications include CompTIA A+, CompTIA Network+, and CompTIA Security+, to name a few. Check out the CompTIA Web site at www.comptia.org for details on other certifications.

CompTIA is huge. Virtually every company of consequence in the IT industry is a member of CompTIA: Microsoft, Dell, Cisco… Name an IT company and it’s probably a member of CompTIA.

The Current CompTIA Network+ Certification Exam Release CompTIA constantly works to provide exams that cover the latest technolo- gies and, as part of that effort, periodically updates its certification objec- tives, domains, and exam questions. This book covers all you need to know to pass the N10-005 CompTIA Network+ exam released in 2011.

How Do I Become CompTIA Network+ Certified? To become CompTIA Network+ certified, you simply pass one computer- based, multiple-choice exam. There are no prerequisites for taking the CompTIA Network+ exam, and no networking experience is needed. You’re not required to take a training course or buy any training materials. The only requirements are that you pay a testing fee to an authorized test- ing facility and then sit for the exam. Upon completion of the exam, you will immediately know whether you passed or failed.

www.comptia.org
BaseTech / Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Chapter 1

Chapter 1: CompTIA Network+ in a Nutshell 3

Once you pass, you become CompTIA Network+ certified for three years. After three years, you’ll need to renew your certification by retaking the current exam or completing approved Continuing Education activities. By completing these activities, you earn credits that (along with an annual fee) allow you to keep your CompTIA Network+ certification. For a full list of approved activities, check out CompTIA’s Web site (www.comptia.org) and search for CompTIA Continuing Education Program.

Now for the details: CompTIA recommends that you have at least nine to twelve months of networking experience and CompTIA A+ knowl- edge, but this is not a requirement. Note the word “recommend.” You may not need experience or CompTIA A+ knowledge, but they help! The CompTIA A+ certification competencies have a degree of overlap with the CompTIA Network+ competencies, such as types of connectors and how networks work.

As for experience, keep in mind that CompTIA Network+ is mostly a practical exam. Those who have been out there supporting real networks will find many of the questions reminiscent of the types of problems they have seen on LANs. The bottom line is that you’ll probably have a much easier time on the CompTIA Network+ exam if you have some CompTIA A+ experience under your belt.

What Is the Exam Like?■■ The CompTIA Network+ exam contains 100 questions, and you have 90 minutes to complete the exam. To pass, you must score at least 720 on a scale of 100–900, at the time of this writing. Check the CompTIA Web site when you get close to testing to determine the current scale: http://certification.comptia.org/getCertified/certifications/network.aspx

The exam questions are divided into five areas that CompTIA calls domains. This table lists the CompTIA Network+ domains and the percent- age of the exam that each represents.

CompTIA Network+ Domain Percentage

1.0 Network Technologies 21%

2.0 Network Installation and Configuration 23%

3.0 Network Media and Topologies 17%

4.0 Network Management 20%

5.0 Network Security 19%

The CompTIA Network+ exam is extremely practical. Questions often present real-life scenarios and ask you to determine the best solution. The CompTIA Network+ exam loves troubleshooting. Let me repeat: many of the test objectives deal with direct, real-world troubleshooting. Be prepared to troubleshoot both hardware and software failures and to answer both “What do you do next?” and “What is most likely the problem?” types of questions.

A qualified CompTIA Network+ certification candidate can install and configure a PC to connect to a network. This includes installing and

www.comptia.org
http://certification.comptia.org/getCertified/certifications/network.aspx
Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks 4

/ Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Chapter 1

testing a network card, configuring drivers, and loading all network soft- ware. The exam will test you on the different topologies, standards, and cabling.

Expect conceptual questions about the Open Systems Interconnec- tion (OSI) seven-layer model. If you’ve never heard of the OSI seven-layer model, don’t worry! This book will teach you all you need to know. While this model rarely comes into play during the daily grind of supporting a network, you need to know the functions and protocols for each layer to pass the CompTIA Network+ exam. You can also expect questions on most of the protocol suites, with heavy emphasis on the TCP/IP suite.

How Do I Take the Test? To take the test, you must go to an authorized testing center. You cannot take the test over the Internet. Prometric and Pearson VUE administer the actual CompTIA Network+ exam. You’ll find thousands of Prometric and Pearson VUE testing centers scattered across the United States and Canada, as well as in over 75 other countries around the world. You may take the exam at any testing center. To locate a testing center and schedule an exam, call Prometric at 888-895-6116 or Pearson VUE at 877-551-7587. You can also visit their Web sites at www.prometric.com and www.vue.com.

How Much Does the Test Cost? CompTIA fixes the price, no matter what testing center you use. The cost of the exam depends on whether you work for a CompTIA member. At press time, the cost for non-CompTIA members is US$246.

If your employer is a CompTIA member, you can save money by obtain- ing an exam voucher. In fact, even if you don’t work for a CompTIA member, you can purchase a voucher from member companies and take advantage of significant member savings. You simply buy the voucher and then use the voucher to pay for the exam. Vouchers are delivered to you on paper and electronically via e-mail. The voucher number is the important thing. That number is your exam payment, so protect it from fellow students until you’re ready to schedule your exam.

If you’re in the United States or Canada, you can visit www.totalsem .com or call 800-446-6004 to purchase vouchers. As I always say, “You don’t have to buy your voucher from us, but for goodness’ sake, get one from somebody!” Why pay full price when you have a discount alternative?

You must pay for the exam when you schedule, whether online or by phone. If you’re scheduling by phone, be prepared to hold for a while. Have your Social Security number (or the international equivalent) ready and either a credit card or a voucher number when you call or begin the online scheduling process. If you require any special accommodations, both Pro- metric and Pearson VUE will be able to assist you, although your selection of testing locations may be a bit more limited.

International prices vary; see the CompTIA Web site for international pricing. Of course, prices are subject to change without notice, so always check the CompTIA Web site for current pricing!

CompTIA occasionally makes changes to the content of the exam, as well as the score necessary to pass it. Always check the Web site of my company, Total Seminars (www.totalsem.com), before scheduling your exam.

Although you can’t take the exam over the Internet, both Prometric and Pearson VUE provide easy online registration. Go to www.prometric.com or www.vue.com to register online.

www.totalsem.com
www.prometric.com
www.vue.com
www.prometric.com
www.vue.com
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BaseTech / Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Chapter 1

Chapter 1: CompTIA Network+ in a Nutshell 5

How to Pass the CompTIA ■■ Network+ Exam

The single most important thing to remember about the CompTIA Net- work+ certification exam is that CompTIA designed it to test the knowl- edge of a technician with as little as nine months of experience—so keep it simple! Think in terms of practical knowledge. Read this book, answer the questions at the end of each chapter, take the practice exams on the media accompanying this book, review any topics you missed, and you’ll pass with flying colors.

Is it safe to assume that it’s probably been a while since you’ve taken an exam? Consequently, has it been a while since you’ve had to study for an exam? If you’re nodding your head yes, you’ll probably want to read the next sections. They lay out a proven strategy to help you study for the CompTIA Network+ exam and pass it. Try it. It works.

Obligate Yourself The first step you should take is to schedule the exam. Ever heard the old adage that heat and pressure make diamonds? Well, if you don’t give your- self a little “heat,” you might procrastinate and unnecessarily delay taking the exam. Even worse, you may end up not taking the exam at all. Do your- self a favor. Determine how much time you need to study (see the next sec- tion), and then call Prometric or Pearson VUE and schedule the exam, giving yourself the time you need to study—and adding a few extra days for safety. Afterward, sit back and let your anxieties wash over you. Suddenly, turning off the television and cracking open the book will become a lot easier! Keep in mind that Prometric and Pearson VUE let you schedule an exam only a few weeks in advance, at most. If you schedule an exam and can’t make it, you must reschedule at least a day in advance or lose your money.

Set Aside the Right Amount of Study Time After helping thousands of techs get their CompTIA Network+ certifica- tion, we at Total Seminars have developed a pretty good feel for the amount of study time needed to pass the CompTIA Network+ exam. Table 1.1 will help you plan how much study time you must devote to the exam. Keep in mind that these are averages. If you’re not a great student or if you’re a little on the nervous side, add another 10 percent. Equally, if you’re the type who can learn an entire semester of geometry in one night, reduce the numbers by 10 percent. To use this table, just circle the values that are most accurate for you and add them up to get the number of study hours.

A complete neophyte will need at least 120 hours of study time. An experienced network technician already CompTIA A+ certified should only need about 24 hours.

Study habits also come into play here. A person with solid study habits (you know who you are) can reduce the number by 15 percent. People with poor study habits should increase that number by 20 percent.

The total hours of study time you need is __________________.

Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks 6

/ Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Chapter 1

Table 1.1 Determining How Much Study Time You Need Amount of Experience

Type of Experience None Once or Twice

On Occasion

Quite a Bit

Installing a SOHO wireless network 4 2 1 1

Installing an advanced wireless network (802.1X, RADIUS, etc.) 2 2 1 1

Installing structured cabling 3 2 1 1

Configuring a home router 5 3 2 1

Configuring a Cisco router 4 2 1 1

Configuring a software firewall 3 2 1 1

Configuring a hardware firewall 2 2 1 1

Configuring an IPv4 client 8 4 2 1

Configuring an IPv6 client 3 3 2 1

Working with a SOHO WAN connection (DSL, cable) 2 2 1 0

Working with an advanced WAN connection (Tx, OCx, ATM) 3 3 2 2

Configuring a DNS server 2 2 2 1

Configuring a DHCP server 2 1 1 0

Configuring a Web application server (HTTP, FTP, SSH, etc.) 4 4 2 1

Configuring a VLAN 3 3 2 1

Configuring a VPN 3 3 2 1 Configuring a dynamic routing protocol (RIP, EIGRP, OSPF) 2 2 1 1

Study for the Test Now that you have a feel for how long it’s going to take to study for the exam, you need a strategy for studying. The following has proven to be an excellent game plan for cramming the knowledge from the study materials into your head.

This strategy has two alternate paths. The first path is designed for highly experienced technicians who have a strong knowledge of PCs and networking and want to concentrate on just what’s on the exam. Let’s call this group the Fast Track group. The second path, and the one I’d strongly recommend, is geared toward people like me: the ones who want to know why things work, those who want to wrap their arms completely around a concept, as opposed to regurgitating answers just to pass the CompTIA Network+ exam. Let’s call this group the Brainiacs.

To provide for both types of learners, I have broken down most of the chapters into two parts:

Historical/Conceptual ■ Although not on the CompTIA Network+ exam, this knowledge will help you understand more clearly what is on the CompTIA Network+ exam.

Test Specific ■ These topics clearly fit under the CompTIA Network+ certification domains.

The beginning of each of these areas is clearly marked with a large ban- ner that looks like the following.

BaseTech / Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Chapter 1

Chapter 1: CompTIA Network+ in a Nutshell 7

Historical/Conceptual If you consider yourself a Fast Tracker, skip everything but the Test Spe- cific section in each chapter. After reading the Test Specific sections, jump immediately to the Chapter Review questions, which concentrate on infor- mation in the Test Specific sections. If you run into problems, review the Historical/Conceptual sections in that chapter. After going through every chapter as described, take the free practice exams on the media that accom- panies the book. First, take them in practice mode, and then switch to final mode. Once you start scoring in the 80–85 percent range, go take the test!

Brainiacs should first read the book—the whole book. Read it as though you’re reading a novel, starting on Page 1 and going all the way through. Don’t skip around on the first read-through, even if you are a highly expe- rienced tech. Because there are terms and concepts that build on each other, skipping around might confuse you, and you’ll just end up closing the book and firing up your favorite PC game. Your goal on this first read is to under- stand concepts—to understand the whys, not just the hows.

Having a network available while you read through the book helps a lot. This gives you a chance to see various concepts, hardware, and configu- ration screens in action as you read about them in the book. Nothing beats doing it yourself to reinforce a concept or piece of knowledge!

You will notice a lot of historical information—the Historical/ Conceptual sections—that you may be tempted to skip. Don’t! Understanding how some of the older stuff worked or how something works conceptually will help you appreciate the reason behind current networking features and equipment, as well as how they function.

After you have completed the first read-through, cozy up for a second. This time, try to knock out one chapter per sitting. Concentrate on the Test Specific sections. Get a highlighter and mark the phrases and sentences that make major points. Take a hard look at the pictures and tables, noting how they illustrate the concepts. Then, answer the end of chapter questions. Repeat this process until you not only get all the questions right, but also understand why they are correct!

Once you have read and studied the material in the book, check your knowledge by taking the practice exams included on the media accompa- nying the book. The exams can be taken in practice mode or final mode. In practice mode, you are allowed to check references in the book (if you want) before you answer each question, and each question is graded immediately. In final mode, you must answer all the questions before you are given a test score. In each case, you can review a results summary that tells you which questions you missed, what the right answer is, and where to study further.

Use the results of the exams to see where you need to bone up, and then study some more and try them again. Continue retaking the exams and reviewing the topics you missed until you are consistently scoring in the 80–85 percent range. When you’ve reached that point, you are ready to pass the CompTIA Network+ exam!

If you have any problems or questions, or if you just want to argue about something, feel free to send an e-mail to me at michaelm@totalsem.com or to my editor, Scott Jernigan, at scottj@totalsem.com.

For additional information about the CompTIA Network+ exam, con- tact CompTIA directly at its Web site: www.comptia.org.

Good luck! —Mike Meyers

We have active and helpful discussion groups at www .totalsem.com/forums. You need to register to participate (though not to read posts), but that’s only to keep the spammers at bay. The forums provide an excellent resource for answers, suggestions, and just socializing with other folks studying for the exam.

Be aware that you may need to return to previous chapters to get the Historical/Conceptual information you need for a later chapter.

www.totalsem.com/forums
www.totalsem.com/forums
www.comptia.org
2 chapter

/ Mike Meyers’ CompTIA Network+ Guide to Managing and Troubleshooting Networks, Third Edition / Meyers / 911-1 / Chapter 2

Network Models

“First we thought the PC was a

calculator. Then we found out how

to turn numbers into letters with

ASCII—and we thought it was

a typewriter. Then we discovered

graphics, and we thought it was

a television. With the World

Wide Web, we’ve realized it’s a

brochure.”

—Douglas aDams

In this chapter, you will learn how to

Describe how models such as the ■■ OSI seven-layer model and the TCP/IP model help technicians understand and troubleshoot networks

Explain the major functions of ■■ networks with the OSI seven-layer model

Describe the major functions of ■■ networks with the TCP/IP model

The CompTIA Network+ certification challenges you to understand virtually every aspect of networking—not a small task. Luckily for you, we use two methods to conceptualize the many parts of a network: the Open Systems

Interconnection (OSI) seven-layer model and the Transmission Control

Protocol/Internet Protocol (TCP/IP) model.

These models act as guidelines and break down how a network functions

into discrete parts called layers. If you want to get into networking—and

if you want to pass the CompTIA Network+ certification exam—you must

understand both the OSI seven-layer model and the TCP/IP model in great

detail.

BaseTech

Chapter 2: Network Models 9

These models provide two tools that make them critical for networking techs. First, the OSI and TCP/IP models provide powerful mental tools for diag- nosing problems. Understand- ing the models enables a tech to determine quickly at what layer a problem can occur and helps him or her zero in on a solution with- out wasting a lot of time on false leads. Second, these models also provide a common language to describe networks—a way for us to communicate with each other about the functions of a network. Figure 2.1 shows a sample Cisco Systems Web page about configuring routing—a topic this book covers in detail later. A router operates at Layer 3 of the OSI seven-layer model, for example, so you’ll hear techs (and Web sites) refer to it as a “Layer 3 switch.”

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