Introduction . . . . . . . . . . . . . . . . . . .
1 Taking a Certification Exam . . . . . . . . . . . . . . . 2
Tracking Your Certification Status . . . . . . . . . . . . 3
How to Prepare for an Exam . . . . . . . . . . . . . . . . 4
What This Book Will Not Do . . . . . . . . . . . . . . . 5
What This Book Is Designed to Do . . . . . . . . . . . . 5
About This Book . . . . . . . . . . . . . . . . . . . 6
CCENT Official Exam Topics . . . .. . . . . 6
Chapter Formats . . . . . . . . . . . . . . . . . 12
Pearson IT Certification Practice Test Engine and Questions on the CD-ROM . . . 14
Install the Software from the CD . . . . . . . . .. . . . . 14
Activate and Download the Practice Exam . . . . . . . . . . 15
Activating Other Exams . . . . . . . . . . . . . . . 16
Contacting the Authors . . . . . . . . . . . 16
Self-Assessment . . . . . . . . . . . . . . . . 17 CCENT in the Real World . . . . . . . . . . . . . 17
The Ideal CCENT Candidate . . . . . . . . . . . . 18
Put Yourself to the Test . . . . . . . . . . 19
CHAPTER 1: Networking Fundamentals . . . . . . . 25 Essential Terms and Components . . . .. . . . . . . . 26
Topologies . . . . . . .. . . . . . . . 27
Ethernet . . . . . . . . . . . . . . 28
WAN Technologies . . . . . . . . . . . 31
Review Questions . . . . . . . . . . . . . . . . . 34
Answers to Review Questions . . . . . . . . . . 36
What Next? . . . . . . . . . . . . . . 37
CHAPTER 2: Network Models . . . . . . . . 39 Cisco Hierarchical Design . . . .. . . . . . . . . . . 40
Access Layer . . . . . . . . . . . . . . . . . 40
Distribution Layer . . . . . . . . . . . . . 41
Core Layer . . . . . . . . . . . . . . . . . 41
Advantages of the Three-Layer Model . . .. . . . . 42
OSI Model . . . . . . . . . . . . . . . . 44
Layer 7: The Application Layer . . . . . . . . . 45
Layer 6: The Presentation Layer . . . . . . . . . 47
Layer 5: The Session Layer . . .. . . . . . . . 47
Layer 4: The Transport Layer . . . . . . . . 47
Layer 3: The Network Layer . . . .. . . . . . . 54
Layer 2: The Data Link Layer . . . . . . . . . . . 56
Layer 1: The Physical Layer . . . . . . . . . . . . . 57
TCP/IP Model . . . . . .. . . . . . . 61
Review Questions . . . . . . . . . .. . . . . . . 64
Answers to Review Questions . . . . . . . . . . . . . 67
CHAPTER 3: Concepts in IP Addressing . . . . . . . 69 Binary . . . . . . . . . . .. . . . . 70
Hexadecimal . . . . . . . .. . . . . . . . 74
Conversion Between Binary, Hex, and Decimal . . . . . . 75
Decimal to Hexadecimal Conversions . . . . . . . . 75
Hexadecimal to Decimal Conversions . . . .. . . . . 75
IP Address Components . . . . . . . . . . . . . 77
Address Class . . . . . . . . . . . . . . 77
Public and Private IP Addresses . . . . . . . . . 78
Default Subnet Mask . . . . . . . . . . . 78
The Network Field . . . . . . .. . . . . . . 79
The Host Field . . . . . . . . . . . . . . . . 80
Nondefault Masks . . . . . . . . . . . . . 80
The Subnet Field . . . . . . . . .. . . . . . 81
Subnetting . . . . . . . . . . . . . . . . . . . . . 82
Address Class and Default Mask . . . . . . . . . . . . . 83
The Increment . . . . . . . . . . . . . . . . . . . 84
Number of Hosts . . . . . . . . .. . . . . . 86
The Broadcast ID . . . . . . . . . . . . . 88
Number of Subnets . . . . . . . . .. . . . . . . 89
Working with Subnetting Questions . . . . . . . 91
The Subnetting Chart . . . . . . . . . . . 93
VLSM . . . . . . . . . . . . . . . . . . . . 96
Route Summarization . . . . . . . . . . . . . . . . 100
Summarization Guidelines . . . . . .. . . . . 102
Determining Summary Addresses . . . . . . . 104
IPv6 . . . . . . . . . . . .. . . . . . . . . 110
IPv6 Address Allocation . . . . . . . . . . . . . . . 112
IPv6 Address Notation . . . . . . . . . . . . 113
Types of IPv6 Addresses . . . . . . . . . . 114
IPv6 Address Configuration . . . . .. . . . 115
IPv6 Router Configuration . . . . . .. . . . . 116
IPv6 Features . . . . . . . . . . . . . . . 117
The IPv6 Header . . . . . . . .. . . . 118
IPv6 Transition Strategies . . . . . . . . . . 119
Review Questions . . . . . . . . . . . .. . . 122
Answers to Review Questions . . . . . . . . . 128
What Next? . . . . . . . . . . . . .. . . . 131
CHAPTER 4: Working with Cisco Equipment. . . . . . . 133 Introducing Your Cisco Gear . . . . . . . . . . . . 134
External Connections . . . . . .. . . . . . . . 135
Other Connections . . . . . . . . . . . . . . . . 139
Connecting and Configuring Cisco Devices . . . . . . . . 141
Device Memory Locations . . . . . . . . . 142
IOS Startup Process . . . . . . .. . . . . 142
Setup Mode . . . . . . . . . . . . . . 144
Configuration Register . . . . .. . . . . 144
Password Recovery . . . . . . . . . . . 145
Command-Line Modes . . . . .. . . . . 146
Command Shortcuts . . . . . . . . . . . . . 148
Context-Sensitive Help . . . . . . . . . 149
Managing IOS Licensing . . . . . . . . . . . 150
Remote Management . . . . . . . . . . . . . . 152
Telnet . . . . . . . . . . . . . . . . . 152
Secure Shell . . . . . . . . . . . . . 154
Cisco Discovery Protocol . . . . . . . . . . . . . . 155
Internet Control Message Protocol . . . . . . 156
Network Time Protocol . . . . . . . . . . . 158
Simple Network Management Protocol. . . . .. . . 158
Syslog . . . . . . . . . . . . . . . . 159
NetFlow . . . . . . . . . . . . . . 159
Basic Switch Configuration . . . . . . . . . . 159
Basic Router Configuration . . . . . . . . . 160
Review Questions . . . . . . . .. . . . . . . 164
Answers to Review Questions . . . . . . . . . . . . . . . 166
What Next? . . . . . . . . . . . . . . . . . . . . 167
CHAPTER 5: Securing Your Cisco Devices . . . . .. . . . . . 169 Securing Routers and Switches . . . . . .. . . . . . . . . . 170
Configuring Password Security . . . . . . . .. . . . 170
Configuring SSH Access to Your Router . . . . . . . . . . 174
External Authentication Methods . . . . . . . . . . . . . 176
Switch Port Security . . . . . . . . . . .. . . . . . . . 178
Security Best Practices for Switches . . . . .. . . . . 178
Review Questions . . . . . . . . . . . . . . . . . . . . 184
Answers to Review Questions . . . . .. . . . . . . . . 186
What Next? . . . . . . . . . . . . . . . . . . . . . . . 187
CHAPTER 6: Basic Switch Operations and Configuration . . . . . . 189 Bridging and Switching . . . . . . . . . . .. . . . . . . . 190
Functions of Bridges and Switches . . . . . . . . . . 191
The Differences Between Switches and Bridges . . . . . . . 195
STP . . . . . . . . . . . . . . .. . . . . . 200
VLAN Concepts and Applications . . . . . . . . . . . . 204
The Definition of a VLAN . . . . . . . . . 206
Benefits of VLANs . . . . . . . .. . . . . . . . 206
Implementing VLANs . . . . . . . . . . 208
VLAN Membership . . . . . . . . . . . . 210
Trunking . . . . . . . . . . . . . . . . . . . . . 212
802.1Q . . . . . . . . . . . . . . . . . . 214
Configuring Switches for Trunking . . . . . . . . . . 215
Review Questions . . . . . . . . . . . . . . . . 219
Answers to Review Questions . . . . . . . . . . . . . 222
What Next? . . . . . . . . . . . . . . . . . 224
CHAPTER 7: Basic Routing . . . . . . 225 Routing Fundamentals . . . . . . . . . . . . . . 226
The Next Hop Concept . . . . . . . . . . 227
Connected Networks . . . . . . . . . . . . 228
Static Routes . . . . . . . . . . . . . . . 229
Default Routes . . . . . . . . . . . . . . 230
Dynamic Routes . . . . . . . . . . 232
Understanding the Router Lookup Process and the IP Route Table . . .. . 235
Inter-VLAN Routing . . . . . . . . . . 242
Router on a Stick . . . . . . . . . 243
L3 Switching . . . . . . . . . . . 245
OSPF . . . . . . . . . . . . . . . . . . . 248
Characteristics . . . . . .. . . . . . . . 249
Configuring Single-Area OSPFv2. . . . . . . . 254
Configuring Single-Area OSPFv3. . . . . . . . . . . 258
Verifying and Troubleshooting OSPF. . . . . . . . 260
Verification of OSPFv3 . . . . . . . . . . . 261
Review Questions . . . . . . . . . . .. . . . . . 265
Answers to Review Questions . . . .. . . . . . 269
CHAPTER 8: Visualizing Data Flow Between Two Hosts on a Network . . . 271 Host-to-Host Direct Communications . . . . . . . . . 272
Host to Host Through a Switch . . . . . . . . . . . 275
Host to Host Through a Router . . . . . . . . . . 278
Review Questions . . . . . . . . . . . . . . . . . . . 283
Answers to Review Questions . . . . . . . . . . . . . 286
What Next? . . . . . . . . . . . . . . 288
CHAPTER 9: IP Access Lists . . . . . . . 289 IP Access Lists as Packet Filters . . . . . . . . . . . . . 290
Types of ACLs . . . . . . . . . . . . . . . 293
Configuring and Implementing . . . . . . . . . . . . . . 296
Configuring Standard ACLs . . . . . . . . . . 297
Configuring Extended ACLs . . . . . . . . . . . 300
Filtering Telnet and SSH Access . . . . . . . . . . 302
Troubleshooting and Verifying ACL Configurations. . . . .. . . . 308
Review Questions . . . . . . . . . . . . . 311
Answers to Review Questions . . . . . . . . . . . . . 316
What Next? . . . . . . . . . . . . . . 318
CHAPTER 10: IP Services . . . . . 319 Network Address Translation . . .. . . . . . . . 320
NAT Terminology . . . . . . . . . . 321
Applications, Advantages, and Disadvantages of NAT . . . . . . . . . 323
Static NAT . . . . . . . . . . . . . . . . . . . 324
Dynamic NAT . . . . .. . . . . . . . . . . 326
PAT . . . . . . . . . . . . . . . . . 328
Verification and Troubleshooting NAT and PAT . . . . . 330
Network Time Protocol . . . . . . . . . . . 334
Configuring an IOS Router as an NTP Client . . . . . . . 335
Verification of NTP . . . . .. . . . . . . . 336
DHCP . . . . . . . . .. . . . . . . . . 338
Configuring an IOS Router as a DHCP Client . . . . . . 338
Configuring an IOS Router as a DHCP Server . . .. . . . 339
Verification of DHCP Operation . . . . . . . . 340
Review Questions . . . . . . .. . . . . . . . . . 343
Answers to Review Questions . . . . . . . . . . . . 345
CHAPTER 11: Troubleshooting . . . . 347 Troubleshoot Layer 1 Problems . . .. . . . . . . . . . . 348
Problems with the Wiring . . . . .. . . . . . . 348
Duplex . . . . . . . . . . . . . . . . . . 349
Finding the Errors . . . . . . .. . . . . . 349
Verify and Troubleshoot VLANs and Port Membership . . . .. . . . 353
Troubleshooting VLANs . . . . .. . . . . . 354
Verify Trunk Configuration and Operation . . . .. . . . . . 357
Is the Link Up and Configured? . . . . . . . . . . 357
VLANs Must Exist for the Trunk to Support Them . . . . . . 357
Administrative Versus Operational . . . . . . . . . 358
Troubleshoot Problems with IP Addressing and Host Configurations . . 361
Verify Hosts Have Correct IP Addresses . . . . . . . . . . 362
How to Remotely Change a Cisco IP Address . . . . . . . . 362
Making Sure That We Have a Default Gateway on Hosts . . . . . . 362
Troubleshooting NAT . . . . . . . .. . . . . . . . . 363
Troubleshoot ACL Issues . . . . . . . . . . . . 365
Review Questions . . . . . . . . . . . . . . . . . . . 368
Answers to Review Questions . . . . . . . . . . . . 375
Practice Exam 1 . . . . . . . . . . . . . . . . 377
Answer Key to Practice Exam 1 . . . . . . . . . . . . 413 Answers at a Glance to Practice Exam 1 . . . . . . . . . 413
Answers with Explanations . . . . . . . .. . . . . 413
Practice Exam 2 . . . . . . . . . . . . .. . . . . 423
Answer Key to Practice Exam 2 . . . . . . . . . . . . . . . 459 Answers at a Glance to Practice Exam 2 . . . . . . . . . . . 459
Answers with Explanations . . . . . . . . . . . . 460
Glossary . . . . . . . . . . . 469 Index . . . . . . . . . . . . . . . . . 487