Table of Contents

Introduction xxi CCENT Exam Objectives xxxii

Assessment Test xxxviii

Chapter 1 Internetworking 1

Internetworking Basics 2

Internetworking Models 10

The Layered Approach 11

Advantages of Reference Models 12

The OSI Reference Model 12

The Application Layer 14

The Presentation Layer 15

The Session Layer 15

The Transport Layer 16

The Network Layer 21

The Data Link Layer 23

The Physical Layer 26

Summary 27

Exam Essentials 28

Written Labs 29

Written Lab 1.1: OSI Questions 29

Written Lab 1.2: Defining the OSI Layers and Devices 30

Written Lab 1.3: Identifying Collision and Broadcast Domains 31

Review Questions 32

Chapter 2 Ethernet Networking and Data Encapsulation 39

Ethernet Networks in Review 40

Collision Domain 41

Broadcast Domain 42

CSMA/CD 43

Half- and Full-Duplex Ethernet 45

Ethernet at the Data Link Layer 47

Ethernet at the Physical Layer 53

Ethernet Cabling 57

Straight-Through Cable 58

Crossover Cable 58

Rolled Cable 60

Fiber Optic 62

Data Encapsulation 64

The Cisco Three-Layer Hierarchical Model 68

The Core Layer 68

The Distribution Layer 70

The Access Layer 70

Summary 71

Exam Essentials 71

Written Labs 72

Written Lab 2.1: Binary/Decimal/Hexadecimal Conversion 73

Written Lab 2.2: CSMA/CD Operations 77

Written Lab 2.3: Cabling 77

Written Lab 2.4: Encapsulation 78

Review Questions 79

Chapter 3 Introduction to TCP/IP 85

Introducing TCP/IP 86

A Brief History of TCP/IP 87

TCP/IP and the DoD Model 87

The Process/Application Layer Protocols 89

The Host-to-Host Layer Protocols 99

The Internet Layer Protocols 108

IP Addressing 116

IP Terminology 116

The Hierarchical IP Addressing Scheme 117

Private IP Addresses (RFC 1918) 122

IPv4 Address Types 124

Layer 2 Broadcasts 124

Layer 3 Broadcasts 124

Unicast Address 125

Multicast Address 126

Summary 127

Exam Essentials 128

Written Labs 130

Written Lab 3.1: TCP/IP 130

Written Lab 3.2: Mapping Applications to the DoD Model 130

Review Questions 132

Chapter 4 Easy Subnetting 137

Subnetting Basics 138

How to Create Subnets 140

Subnet Masks 140

Classless Inter-Domain Routing (CIDR) 142

IP Subnet-Zero 144

Subnetting Class C Addresses 144

Subnetting Class B Addresses 156

Subnetting Class A Addresses 165

Summary 168

Exam Essentials 168

Written Labs 169

Written Lab 4.1: Written Subnet Practice #1 169

Written Lab 4.2: Written Subnet Practice #2 170

Written Lab 4.3: Written Subnet Practice #3 171

Review Questions 172

Chapter 5 VLSMs, Summarization, and Troubleshooting TCP/IP 179

Variable Length Subnet Masks (VLSMs) 180

VLSM Design 182

Implementing VLSM Networks 182

Summarization 191

Troubleshooting IP Addressing 194

Determining IP Address Problems 196

Summary 201

Exam Essentials 202

Written Lab 5 203

Review Questions 204

Chapter 6 Cisco?s Internetworking Operating System (IOS) 211

The IOS User Interface 213

Cisco IOS 214

Connecting to a Cisco IOS Device 214

Bringing Up a Switch 216

Command-Line Interface (CLI) 217

Entering the CLI 217

Overview of Router Modes 217

CLI Prompts 218

Editing and Help Features 221

Administrative Configurations 226

Hostnames 226

Banners 227

Setting Passwords 229

Encrypting Your Passwords 235

Descriptions 237

Router and Switch Interfaces 239

Bringing Up an Interface 242

Viewing, Saving, and Erasing Configurations 248

Deleting the Configuration and Reloading the Device 250

Verifying Your Configuration 251

Summary 262

Exam Essentials 263

Written Lab 6 266

Hands-on Labs 266

Hands-on Lab 6.1: Erasing an Existing Configuration 267

Hands-on Lab 6.2: Exploring User, Privileged, and Configuration Modes 267

Hands-on Lab 6.3: Using the Help and Editing Features 268

Hands-on Lab 6.4: Saving a Configuration 269

Hands-on Lab 6.5: Setting Passwords 270

Hands-on Lab 6.6: Setting the Hostname, Descriptions, IP Address, and Clock Rate 272

Review Questions 275

Chapter 7 Managing a Cisco Internetwork 281

The Internal Components of a Cisco Router and Switch 282

The Router and Switch Boot Sequence 283

Backing Up and Restoring the Cisco Configuration 284

Backing Up the Cisco Configuration 284

Restoring the Cisco Configuration 286

Erasing the Configuration 287

Configuring DHCP 288

DHCP Relay 289

Verifying DHCP on Cisco IOS 290

Network Time Protocol (NTP) 291

Using Cisco Discovery Protocol (CDP) 293

Getting CDP Timers and Holdtime Information 293

Gathering Neighbor Information 294

Documenting a Network Topology Using CDP 298

Using Telnet 301

Telnetting into Multiple Devices Simultaneously 303

Checking Telnet Connections 304

Checking Telnet Users 304

Closing Telnet Sessions 304

Resolving Hostnames 305

Building a Host Table 305

Using DNS to Resolve Names 307

Checking Network Connectivity and Troubleshooting 309

Using the ping Command 310

Using the traceroute Command 310

Debugging 312

Using the show processes Command 314

Summary 315

Exam Essentials 315

Written Lab 7 317

Written Lab 7.1: IOS Management 317

Written Lab 7.2: Router Memory 317

Hands-on Labs 318

Hands-on Lab 7.1: Backing Up the Router Configuration 318

Hands-on Lab 7.2: Using the Cisco Discovery

Protocol (CDP) 319

Hands-on Lab 7.3: Using Telnet 320

Hands-on Lab 7.4: Resolving Hostnames 321

Review Questions 323

Chapter 8 IP Routing 329

Routing Basics 331

The IP Routing Process 333

The Cisco Router Internal Process 339

Testing Your IP Routing Understanding 340

Configuring IP Routing 344

Configuring IP Routing in Our Network 354

Static Routing 355

Default Routing 360

Dynamic Routing 363

Routing Protocol Basics 363

Routing Information Protocol (RIP) 365

Configuring RIP Routing 365

Holding Down RIP Propagations 369

Summary 371

Exam Essentials 372

Written Lab 8 374

Hands-on Labs 374

Hands-on Lab 8.1: Creating Static Routes 375

Hands-on Lab 8.2: Configuring RIP Routing 376

Review Questions 378

Chapter 9 Open Shortest Path First (OSPF) 383

Open Shortest Path First (OSPF) Basics 384

OSPF Terminology 387

OSPF Operation 389

Configuring OSPF 391

Enabling OSPF 391

Configuring OSPF Areas 392

Configuring Our Network with OSPF 395

OSPF and Loopback Interfaces 400

Configuring Loopback Interfaces 401

Verifying OSPF Configuration 403

The show ip ospf Command 404

The show ip ospf database Command 405

The show ip ospf interface Command 406

The show ip ospf neighbor Command 407

The show ip protocols Command 409

Summary 409

Exam Essentials 410

Written Lab 9 411

Hands-on Labs 411

Hands-on Lab 9.1: Enabling the OSPF Process 412

Hands-on Lab 9.2: Configuring OSPF Interfaces 413

Hands-on Lab 9.3: Verifying OSPF Operation 414

Review Questions 415

Chapter 10 Layer 2 Switching 423

Switching Services 424

Three Switch Functions at Layer 2 425

Port Security 429

Configuring Catalyst Switches 434

Catalyst Switch Configuration 434

Verifying Cisco Catalyst Switches 442

Summary 445

Exam Essentials 445

Written Lab 10 446

Hands-on Labs 446

Lab 10.1: Configuring Layer 2 Switches 447

Lab 10.2: Verifying Layer 2 Switches 448

Lab 10.3: Configuring Port Security 448

Review Questions 450

Chapter 11 VLANs and Inter-VLAN Routing 457

VLAN Basics 458

Broadcast Control 461

Security 462

Flexibility and Scalability 462

Identifying VLANs 463

Frame Tagging 465

VLAN Identification Methods 466

Routing between VLANs 467

Configuring VLANs 470

Assigning Switch Ports to VLANs 473

Configuring Trunk Ports 474

Configuring Inter-VLAN Routing 478

Summary 485

Exam Essentials 486

Written Lab 11 487

Hands-on Labs 487

Hands-on Lab 11.1: Configuring and Verifying VLANs 488

Hands-on Lab 11.2: Configuring and Verifying Trunk Links 489

Hands-on Lab 11.3: Configuring Router on a Stick Routing 490

Hands-on Lab 11.4: Configuring IVR with a Layer 3 Switch 490

Review Questions 492

Chapter 12 Security 499

Perimeter, Firewall, and Internal Routers 500

Introduction to Access Lists 501

Mitigating Security Issues with ACLs 504

Standard Access Lists 505

Wildcard Masking 506

Standard Access List Example 508

Controlling VTY (Telnet/SSH) Access 512

Extended Access Lists 513

Extended Access List Example 1 517

Extended Access List Example 2 519

Extended Access List Example 3 520

Named ACLs 521

Remarks 523

Monitoring Access Lists 524

Summary 526

Exam Essentials 527

Written Lab 12 528

Hands-on Labs 528

Hands-on Lab 12.1: Standard IP Access Lists 529

Hands-on Lab 12.2: Extended IP Access Lists 530

Review Questions 533

Chapter 13 Network Address Translation (NAT) 539

When Do We Use NAT? 540

Types of Network Address Translation 542

NAT Names 542

How NAT Works 543

Static NAT Configuration 545

Dynamic NAT Configuration 546

PAT (Overloading) Configuration 546

Simple Verification of NAT 547

Testing and Troubleshooting NAT 548

Summary 553

Exam Essentials 554

Written Lab 13 555

Hands-on Labs 555

Lab 13.1: Preparing for NAT 556

Lab 13.2: Configuring Dynamic NAT 558

Lab 13.3: Configuring PAT 559

Review Questions 562

Chapter 14 Internet Protocol Version 6 (IPv6) 567

Why Do We Need IPv6? 569

The Benefits and Uses of IPv6 569

IPv6 Addressing and Expressions 571

Shortened Expression 572

Address Types 573

Special Addresses 574

How IPv6 Works in an Internetwork 575

Manual Address Assignment 576

Stateless Autoconfiguration (EUI-64) 576

DHCPv6 (Stateful) 579

IPv6 Header 580

ICMPv6 581

IPv6 Routing Protocols 584

Static Routing with IPv6 584

OSPFv3 585

Configuring IPv6 on Our Internetwork 586

Configuring Routing on Our Internetwork 589

Verifying OSPFv3 592

Summary 597

Exam Essentials 597

Written Labs 599

Written Lab 14.1 599

Written Lab 14.2 599

Hands-on Labs 600

Hands-on Lab 14.1: Manual and Stateful Autoconfiguration 600

Hands-on Lab 14.2: Static and Default Routing 602

Hands-on Lab 14.3: OSPFv3 603

Review Questions 605

Appendix A Answers to Written Labs 611

Chapter 1: Internetworking 612

Written Lab 1.1: OSI Questions 612

Written Lab 1.2: Defining the OSI Layers and Devices 613

Written Lab 1.3: Identifying Collision and Broadcast Domains 614

Chapter 2: Ethernet Networking and Data Encapsulation 615

Written Lab 2.1: Binary/Decimal/Hexadecimal Conversion 615

Written Lab 2.2: CSMA/CD Operations 617

Written Lab 2.3: Cabling 617

Written Lab 2.4: Encapsulation 618

Chapter 3: Introduction to TCP/IP 618

Written Lab 3.1: TCP/IP 618

Written Lab 3.2: Mapping Applications to the DoD Model 618

Chapter 4: Easy Subnetting 619

Written Lab 4.1: Written Subnet Practice #1 619

Written Lab 4.2: Written Subnet Practice #2 620

Written Lab 4.3: Written Subnet Practice #3 621

Chapter 5: VLSMs, Summarization and Troubleshooting TCP/IP 621

Chapter 6: Cisco?s Internetworking Operating System (IOS) 622

Written Lab 6 622

Chapter 7: Managing a Cisco Internetwork 622

Written Lab 7.1: IOS Management 622

Written Lab 7.2: Router Memory 623

Chapter 8: IP Routing 623

Chapter 9: Open Shortest Path First (OSPF) 624

Chapter 10: Layer 2 Switching 624

Chapter 11: VLANs and InterVLAN Routing 624

Chapter 12: Security 625

Chapter 13: Network Address Translation 625

Chapter 14: Internet Protocol Version 6 (IPv6) 626

Written Lab 14.1 626

Written Lab 14.2 626

Appendix B Answers to Review Questions 627

Chapter 1: Internetworking 628

Chapter 2: Ethernet Networking and Data Encapsulation 630

Chapter 3: Introduction to TCP/IP 631

Chapter 4: Easy Subnetting 633

Chapter 5: VLSMs, Summarization and Troubleshooting TCP/IP 635

Chapter 6: Cisco?s Internetworking Operating System (IOS) 637

Chapter 7: Managing a Cisco Internetwork 639

Chapter 8: IP Routing 641

Chapter 9: Open Shortest Path First (OSPF) 642

Chapter 10: Layer 2 Switching 644

Chapter 11: VLANs and InterVLAN Routing 647

Chapter 12: Security 648

Chapter 13: Network Address Translation 651

Chapter 14: Internet Protocol Version 6 (IPv6) 652

Appendix C Disabling and Configuring Network Services 655

Blocking SNMP Packets 656

Disabling Echo 656

Turning off BootP and Auto-Config 657

Disabling the HTTP Interface 658

Disabling IP Source Routing 658

Disabling Proxy ARP 658

Disabling Redirect Messages 658

Disabling the Generation of ICMP Unreachable Messages 659

Disabling Multicast Route Caching 659

Disabling the Maintenance Operation Protocol (MOP) 659

Turning Off the X.25 PAD Service 660

Enabling the Nagle TCP Congestion Algorithm 660

Logging Every Event 660

Disabling Cisco Discovery Protocol 661

Disabling the Default Forwarded UDP Protocols 661

Cisco?s Auto Secure 662

Appendix D About the Additional Study Tools 667

Additional Study Tools 668

Test Engine 668

Electronic Flashcards 668

Videos 668

Network Simulator 669

PDF of Glossary of Terms 669

System Requirements 669

Using the Study Tools 669

Troubleshooting 670

Customer Care 670

Index 671

About the Author

Todd Lammle is the Authority on Cisco Certification and Internetworking and is Cisco certified in all Cisco certification categories. He is a world-renowned author, speaker, trainer, and consultant. Todd has three decades of experience working with LANs, WANs, and large enterprise licensed and unlicensed wireless networks, including the implementation of large Cisco Data Centers world-wide. His books draw on his practical experience working on the largest networks in the world at companies such as Xerox, Hughes Aircraft, Texaco, AAA, Cisco and Toshiba. He has published over 60 books, including the very popular CCNA: Cisco Certified Network Associate Study Guide , CCNA Wireless Study Guide , and CCNA Data Center Study Guide , all from Sybex. He runs an international consulting and training company based in Colorado, Texas, and San Francisco. You can reach Todd through his forum and blog at www.lammle.com .