Todd Lammle, Network+, CCSI, CCNA, CCNP, is the networking authority. He has been involved in computers and networking with Fortune 500 companies for over 30 years. Todd is President of GlobalNet System Solutions, Inc., a networking integration and training firm. He is the bestselling author of numerous titles, with over 900,000 copies of his books in print. He can be reached through his website at www.lammle.com.

Introduction xxxi Assessment Test xli Chapter 1 Introduction to Networks 1 First Things First: What's a Network? 3 The Local Area Network 4 Common Network Components 6 Metropolitan Area Network 9 Wide Area Network 9 Personal Area Network 10 Campus Area Network 10 Storage Area Network 10 Software-Defined Wide Area Network 11 Multiprotocol Label Switching 11 Multipoint Generic Routing Encapsulation 12 Network Architecture: Peer-to-Peer or Client-Server? 12 Physical Network Topologies 14 Bus Topology 14 Star Topology 15 Ring Topology 17 Mesh Topology 17 Point-to-Point Topology 18 Point-to-Multipoint Topology 19 Hybrid Topology 20 Topology Selection, Backbones, and Segments 21 Selecting the Right Topology 22 The Network Backbone 22 Network Segments 23 Service-Related Entry Points 23 Service Provider Links 23 Virtual Networking 24 Summary 24 Exam Essentials 25 Written Lab 25 Review Questions 26 Chapter 2 The Open Systems Interconnection Specifications 31 Internetworking Models 32 The Layered Approach 33 Advantages of Reference Models 33 The OSI Reference Model 34 The Application Layer 36 The Presentation Layer 37 The Session Layer 37 The Transport Layer 37 The Network Layer 43 The Data Link Layer 46 The Physical Layer 48 Introduction to Encapsulation 49 Modulation Techniques 50 Summary 51 Exam Essentials 51 Written Lab 52 Review Questions 53 Chapter 3 Networking Connectors and Wiring Standards 57 Physical Media 59 Coaxial Cable 60 Twisted-Pair Cable 62 Twinaxial Cable 62 Fiber-Optic Cable 66 Transceivers 71 Media Converters 72 Serial Cables 74 Cable Properties 76 Transmission Speeds 76 Distance 76 Duplex 77 Noise Immunity (Security, EMI) 77 Frequency 77 Wiring Standards 78 T568A vs. T568B 78 Straight-Through Cable 80 Crossover Cable 81 Rolled/Rollover Cable 83 T1 Crossover Cable 83 Installing Wiring Distributions 85 MDF/IDF 85 Summary 87 Exam Essentials 88 Written Lab 88 Review Questions 89 Chapter 4 The Current Ethernet Specifications 93 Network Basics 94 Ethernet Basics 96 Collision Domain 96 Broadcast Domain 97 CSMA/CD 97 Broadband/Baseband 99 Bit Rates vs. Baud Rate 99 Wavelength 99 Half-and Full-Duplex Ethernet 100 Ethernet at the Data Link Layer 102 Binary to Decimal and Hexadecimal Conversion 102 Ethernet Addressing 106 Ethernet Frames 107 Ethernet at the Physical Layer 109 Ethernet over Other Standards (IEEE 1905.1-2013) 115 Ethernet over Power Line 115 Ethernet over HDMI 117 Bidirectional Wavelength-Division Multiplexing (WDM) 117 Course Wavelength-Division Multiplexing (CWDM) 117 Dense Wavelength-Division Multiplexing (DWDM) 117 Summary 118 Exam Essentials 119 Written Lab 119 Review Questions 124 Chapter 5 Networking Devices 129 Common Network Connectivity Devices 132 Network Interface Card 133 Hub 135 Bridge 135 Switch 136 Router 137 Firewall 141 IDS/IPS 142 HIDS 142 Access Point 142 Wireless Range Extender 143 Wireless LAN Controller 143 Load Balancer 144 Contention Methods 144 Dynamic Host Configuration Protocol Server 147 IPAM 152 Other Specialized Devices 152 Multilayer Switch 153 Domain Name Service Server 153 Network Time Protocol 160 Proxy Server 160 Encryption and Content Filtering 162 Analog Modem 163 Packet Shaper 164 VPN Concentrator/Headend 164 Media Converter 165 VoIP PBX 165 VoIP Endpoint 166 NGFW/Layer 7 Firewall 166 VoIP Gateway 166 Cable Modem 166 DSL Modem 166 Networked Devices 167 VoIP Phones 167 Printers 167 Physical Access Control Devices 167 Cameras 167 Heating Ventilation, and Air Conditioning (HVAC) Sensors 167 Internet of Things (IoT) 168 Industrial Control Systems 168 Planning and Implementing a Basic SOHO Network Using Network Segmentation 168 Determining Requirements 169 Switches and Bridges at the Data Link Layer 175 Hubs at the Physical Layer 177 Environmental Considerations 178 Summary 178 Exam Essentials 179 Written Lab 180 Review Questions 181 Chapter 6 Introduction to the Internet Protocol 185 Introducing TCP/IP 188 A Brief History of TCP/IP 188 TCP/IP and the DoD Model 189 The Process/Application Layer Protocols 191 The Host-to-Host Layer Protocols 204 The Internet Layer Protocols 210 Data Encapsulation 220 Summary 224 Exam Essentials 224 Written Lab 225 Review Questions 226 Chapter 7 IP Addressing 231 IP Terminology 233 The Hierarchical IP Addressing Scheme 234 Network Addressing 235 Private IP Addresses (RFC 1918) 239 IPv4 Address Types 241 Layer 2 Broadcasts 242 Layer 3 Broadcasts 242 Unicast Address 243 Multicast Address (Class D) 243 Internet Protocol Version 6 (IPv6) 243 Why Do We Need IPv6? 244 The Benefits of and Uses for IPv6 244 IPv6 Addressing and Expressions 246 Shortened Expression 246 Address Types 247 Special Addresses 248 Stateless Address Autoconfiguration (SLAAC) 249 DHCPv6 (Stateful) 251 Migrating to IPv6 251 Summary 253 Exam Essentials 254 Written Labs 255 Written Lab 7.1 255 Written Lab 7.2 255 Review Questions 257 Chapter 8 IP Subnetting, Troubleshooting IP, and Introduction to NAT 261 Subnetting Basics 263 How to Create Subnets 264 Subnet Masks 265 Classless Inter-Domain Routing (CIDR) 266 Subnetting Class C Addresses 268 Subnetting Class B Addresses 278 Troubleshooting IP Addressing 286 Determining IP Address Problems 289 Introduction to Network Address Translation (NAT) 294 Types of Network Address Translation 295 NAT Names 295 How NAT Works 296 Summary 298 Exam Essentials 298 Written Lab 299 Review Questions 300 Chapter 9 Introduction to IP Routing 305 Routing Basics 306 The IP Routing Process 309 Testing Your IP Routing Understanding 315 Static and Dynamic Routing 316 Summary 319 Exam Essentials 319 Written Lab 320 Review Questions 321 Chapter 10 Routing Protocols 325 Routing Protocol Basics 326 Administrative Distances 327 Classes of Routing Protocols 329 Distance-Vector Routing Protocols 330 Routing Information Protocol (RIP) 332 RIP Version 2 (RIPv2) 332 VLSMs and Discontiguous Networks 333 EIGRP 336 Border Gateway Protocol (BGP) 338 Link-State Routing Protocols 340 Open Shortest Path First (OSPF) 340 Intermediate System-to-Intermediate System (IS-IS) 343 High Availability 344 Hot Standby Router Protocol (HSRP) 346 Virtual Router Redundancy Protocol 350 Advanced IPv6 Concepts 351 Router Advertisement 351 Neighbor Discovery Protocol 353 Tunneling 354 Dual Stack 357 IPv6 Routing Protocols 357 RIPng 358 EIGRPv6 358 OSPFv3 359 Summary 359 Exam Essentials 359 Written Lab 360 Review Questions 361 Chapter 11 Switching and Virtual LANs 365 Networking Before Layer 2 Switching 367 Switching Services 370 Limitations of Layer 2 Switching 371 Bridging vs. LAN Switching 372 Three Switch Functions at Layer 2 372 Distributed Switching 378 Spanning Tree Protocol 378 Spanning Tree Port States 379 STP Convergence 380 Rapid Spanning Tree Protocol 802.1w 381 Virtual LANs 382 VLAN Basics 383 Quality of Service 386 VLAN Memberships 387 Static VLANs 387 Dynamic VLANs 388 Identifying VLANs 388 VLAN Identification Methods 390 VLAN Trunking Protocol 392 VTP Modes of Operation 393 Do We Really Need to Put an IP Address on a Switch? 394 Switch Port Protection 396 Port Bonding 399 Device Hardening 401 Two Additional Advanced Features of Switches 401 Power over Ethernet (802.3af, 802.3at) 401 Port Mirroring/Spanning (SPAN/RSPAN) 404 Summary 405 Exam Essentials 406 Written Lab 406 Review Questions 408 Chapter 12 Wireless Networking 413 Introduction to Wireless Technology 415 Cellular Technologies 418 The 802.11 Standards (Regulatory Impacts) 419 2.4 GHz (802.11b) 421 2.4 GHz (802.11g) 422 5 GHz (802.11a) 423 5 GHz (802.11h) 424 2.4 GHz/5 GHz (802.11n) 425 5 GHz (802.11ac) 426 WiFi 6 (802.11ax) 426 Comparing 802.11 Standards 427 Range and Speed Comparisons 428 Wireless Network Components 428 Wireless Access Points 429 Wireless Network Interface Card 430 Wireless Antennas 431 Installing a Wireless Network 432 Ad Hoc Mode: Independent Basic Service Set 432 Infrastructure Mode: Basic Service Set 433 Wireless Controllers 434 Mobile Hot Spots 436 Signal Degradation 438 Other Network Infrastructure Implementations 438 Technologies That Facilitate the Internet of Things (IoT) 440 Installing and Configuring WLAN Hardware 441 Site Survey 447 Providing Capacity 448 Multiple Floors 449 Location-Based WLAN 450 Site Survey Tools 450 Wireless Security 451 Wireless Threats 451 Open Access 455 Service Set Identifiers, Wired Equivalent Privacy, and Media Access Control Address Authentication 455 Remote Authentication Dial-In User Service (802.1X) 457 Temporal Key Integrity Protocol 458 Wi-Fi Protected Access or WPA2 Pre-Shared Key 459 Summary 462 Exam Essentials 462 Written Lab 464 Review Questions 465 Chapter 13 Using Statistics and Sensors to Ensure Network Availability 469 Performance Metrics/Sensors 471 Device/Chassis 471 Network Metrics 473 SNMP 474 Traps 475 Object Identifiers (OIDs) 476 Management Information Bases (MIBs) 476 Network Device Logs 476 Log Reviews 476 Logging Levels/Severity Levels 480 Interface Statistics/Status 482 Link State (Up/Down) 482 Speed/Duplex 483 Send/Receive Traffic 484 Cyclic Redundancy Checks (CRCs) 485 Protocol Packet and Byte Counts 486 Interface Errors or Alerts 486 CRC Errors 487 Giants and Runts 488 Encapsulation Errors 488 Environmental Factors and Sensors 489 Temperature 489 Humidity 489 Electrical 490 Flooding 495 Baselines 495 NetFlow Data 496 NetFlow Overview and Flows 496 Uptime/Downtime 498 Summary 498 Exam Essentials 498 Written Lab 499 Review Questions 501 Chapter 14 Organizational Documents and Policies 505 Plans and Procedures 507 Change Management 508 Incident Response Plan 510 Disaster Recovery Plan 510 Business Continuity Plan 510 System Life Cycle 511 Standard Operating Procedures 511 Hardening and Security Policies 511 Acceptable Use Policy 512 Password Policy 512 Bring Your Own Device (BYOD) Policy 513 Remote Access Policy 513 Onboarding and Offboarding Policy 513 Security Policy 514 Data Loss Prevention 519 Common Documentation 519 Physical Network Diagram 520 Logical Network Diagram 524 Wiring Diagram 525 Site Survey Report 526 Audit and Assessment Report 526 Baseline Configurations 527 Common Agreements 528 Nondisclosure Agreement (NDA) 528 Service-Level Agreement (SLA) 529 Memorandum of Understanding (MOU) 529 Summary 529 Exam Essentials 529 Written Lab 530 Review Questions 531 Chapter 15 High Availability and Disaster Recovery 533 Load Balancing 535 Multipathing 536 Network Interface Card (NIC) Teaming 537 Redundant Hardware/Clusters 538 Switches 538 Routers 540 Firewalls 542 Facilities and Infrastructure Support 542 Uninterruptible Power Supply (UPS) 542 Power Distribution Units (PDUs) 543 Generator 543 HVAC 544 Fire Suppression 544 Redundancy and High Availability (HA) Concepts 545 Recovery Sites 545 Cold Site 545 Warm Site 545 Hot Site 546 Cloud Site 546 Active/Active vs. Active/Passive 546 Mean Time to Repair (MTTR) 553 Mean Time Between Failure (MTBF) 554 Recovery Time Objective (RTO) 554 Recovery Point Objective (RPO) 554 Network Device Backup/Restore 554 State/Configuration 554 Summary 555 Exam Essentials 555 Written Lab 556 Review Questions 557 Chapter 16 Common Security Concepts 559 Confidentiality, Integrity, and Availability (CIA) 561 Confidentiality 561 Integrity 561 Availability 562 Threats 562 Internal 562 External 562 Vulnerabilities 562 Common Vulnerabilities and Exposures (CVE) 563 Zero-Day 563 Exploits 563 Least Privilege 563 Role-Based Access 564 Zero Trust 564 Defense in Depth 564 Network Segmentation Enforcement 564 Screened Subnet (aka Demilitarized Zone) 565 Separation of Duties 565 Network Access Control 566 Honeypot 567 Authentication Methods 567 Multifactor 567 Authentication, Authorization, and Accounting (AAA) 568 Remote Authentication Dial-In User Service (RADIUS) 568 Terminal Access Controller Access Control System Plus (TACACS+) 568 Single Sign-On (SSO) 570 LDAP 570 Kerberos 570 Local Authentication 571 802.1X 571 Extensible Authentication Protocol (EAP) 572 Security Risk Assessments 573 Threat Assessment 573 Vulnerability Assessment 574 Penetration Testing 575 Business Risk Assessments 575 Security Information and Event Management (SIEM) 576 Notifications 576 Summary 576 Exam Essentials 577 Written Lab 577 Review Questions 578 Chapter 17 Common Types of Attacks 581 Technology-Based Attacks 582 Denial of Service (DoS)/Distributed Denial of Service (DDoS) 583 On-Path Attack (Previously Known as Man-in-the-Middle Attack) 588 DNS Poisoning 589 VLAN Hopping 589 ARP Spoofing 590 Rogue DHCP 590 Rogue Access Point (AP) 591 Evil Twin 592 Ransomware 593 Password Attacks 593 MAC Spoofing 594 IP Spoofing 594 Deauthentication 594 Malware 594 Human and Environmental 598 Social Engineering 598 Phishing 599 Environmental 599 Summary 600 Exam Essentials 600 Written Lab 601 Review Questions 602 Chapter 18 Network Hardening Techniques 605 Best Practices 607 Secure SNMP 608 Router Advertisement (RA) Guard 608 Port Security 608 Dynamic ARP Inspection 609 Control Plane Policing 609 Private VLANs 609 Disable Unneeded Switchports 610 Disable Unneeded Network Services 610 Change Default Passwords 610 Password Complexity/Length 610 Enable DHCP Snooping 613 Change Default VLAN 613 Patch and Firmware Management 614 Access Control List 615 Role-Based Access 616 Firewall Rules 617 Wireless Security 618 MAC Filtering 618 Antenna Placement 618 Power Levels 619 Wireless Client Isolation 619 Guest Network Isolation 620 Preshared Keys (PSKs) 620 EAP 620 Geofencing 620 Captive Portal 621 IoT Access Considerations 621 Summary 621 Exam Essentials 621 Written Lab 622 Review Questions 623 Chapter 19 Remote Access Security 625 Site-to-Site VPN 626 Client-to-Site VPN 626 Clientless VPN 627 Split Tunnel vs. Full Tunnel 628 Remote Desktop Connection 628 Remote Desktop Gateway 629 SSH 630 Virtual Network Computing (VNC) 630 Virtual Desktop 631 Authentication and Authorization Considerations 631 In-Band vs. Out-of-Band Management 631 Summary 632 Exam Essentials 632 Written Lab 632 Review Questions 634 Chapter 20 Physical Security 637 Detection Methods 639 Cameras 639 Motion Detection 640 Asset Tags 641 Tamper Detection 641 Prevention Methods 642 Employee Training 642 Access Control Hardware 643 Locking Racks 643 Locking Cabinets 644 Access Control Vestibule (Previously Known as a Mantrap) 644 Smart Lockers 645 Asset Disposal 646 Factory Reset/Wipe Configuration 646 Sanitize Devices for Disposal 646 Summary 647 Exam Essentials 647 Written Lab 648 Review Questions 649 Chapter 21 Data Center Architecture and Cloud Concepts 651 Data Center Network Architectures 654 Access/Edge Layer 654 Distribution Layer 655 Core Layer 655 Software-Defined Networking 655 Application Layer 656 Control Layer 656 Infrastructure Layer 656 Management Plane 656 Spine-Leaf-Based Two-Tier Networks 657 Top-of-Rack Switching 658 Backbone 658 Traffic Flows 658 North-South 659 East-West 659 Branch Office vs. On-premises Data Center vs. Colocation 660 Cloud Computing and Its Effect on the Enterprise Network 661 Service Models 663 Overview of Network Programmability in Enterprise Network 665 Software-Defined Networking 666 Application Programming Interfaces (APIs) 666 Southbound APIs 667 Northbound APIs 669 Managing Network Documentation 670 Using SNMP 670 Schematics and Diagrams 671 Network Monitoring 676 Baselines 676 Processes 676 Onboarding and Offboarding of Mobile Devices 677 NAC 677 Policies, Procedures, and Regulations 677 Safety Practices 681 Implementing Network Segmentation 686 Network Optimization 689 Reasons to Optimize Your Network's Performance 689 How to Optimize Performance 691 Unified Communications 694 Traffic Shaping 694 Load Balancing 695 High Availability 695 Caching Engines 695 Fault Tolerance 696 Archives/Backups 696 Common Address Redundancy Protocol 697 Virtual Networking 697 Locating and Installing Equipment 708 Change Management Procedures 715 Summary 717 Exam Essentials 719 Written Lab 720 Review Questions 721 Chapter 22 Ensuring Network Availability 725 Performance Metrics/Sensors 727 Network Metrics 728 SNMP 729 Network Device Logs 731 Interface Statistics/Status 733 Interface Errors 734 Environmental Factors and Sensors 735 Baseline 736 NetFlow 737 Uptime 738 Downtime 738 Summary 739 Exam Essentials 739 Written Lab 740 Review Questions 741 Chapter 23 Cable Connectivity Issues and Tools 745 Specifications and Limitations 747 Cable Considerations 747 Cable Applications 748 Common Issues 749 Identifying Hardware Tools 751 Cable Testers 752 Protocol Analyzer 755 Certifiers 755 Time-Domain Reflectometer 756 Optical Time-Domain Reflectometer 756 Multimeter 757 Spectrum Analyzer 758 Toner Generator (Probe) 759 Tap 760 Metrics 760 Butt Set 761 Punch-Down Tool 761 Cable Snips/Cutters 763 Voltage Event Recorder (Power) 763 Fiber Light Meter 764 Fiber Fusion Splicer 764 Summary 765 Exam Essentials 765 Written Lab 766 Review Questions 767 Chapter 24 Network Troubleshooting Methodology 771 Narrowing Down the Problem 775 Did You Check the Super Simple Stuff? 776 Is Hardware or Software Causing the Problem? 780 Is It a Workstation or a Server Problem? 781 Which Segments of the Network Are Affected? 781 Is It Bad Cabling? 782 Troubleshooting Steps 791 Step 1: Identify the Problem 792 Step 2: Establish a Theory of Probable Cause 796 Step 3: Test the Theory to Determine Cause 806 Step 4: Establish a Plan of Action to Resolve the Problem and Identify Potential Effects 809 Step 5: Implement the Solution or Escalate as Necessary 810 Step 6: Verify Full System Functionality, and If Applicable, Implement Preventative Measures 813 Step 7: Document Findings, Actions, Outcomes, and Lessons Learned 814 Troubleshooting Tips 815 Don't Overlook the Small Stuff 815 Prioritize Your Problems 815 Check the Software Configuration 816 Don't Overlook Physical Conditions 817 Don't Overlook Cable Problems 817 Check for Viruses 818 Summary 818 Exam Essentials 818 Written Lab 819 Review Questions 821 Chapter 25 Network Software Tools and Commands 825 Software Tools 827 Wi-Fi Analyzers 827 Protocol Analyzer/Packet Capture 828 Bandwidth Speed Testers 829 Port Scanners 830 NetFlow Analyzers 830 Trivial File Transfer Protocol (TFTP) Server 831 Connectivity Software 831 IP Scanner 832 Using traceroute 833 Using ipconfig, ifconfig, and ip 836 Using the ipconfig Utility 836 Using the ifconfig Utility 840 Using the ip Utility 840 Using the iptables Utility 841 Examples of iptables 841 Using the ping Utility 841 Using the Address Resolution Protocol 845 The Windows ARP Table 845 Using the arp Utility 846 Using the nslookup Utility 849 Resolving Names with the Hosts File 850 Using the Mtr Command (pathping) 852 Using the Nmap Utility 853 Using the route Command 854 Using the route Command Options 854 Some Examples of the route Command 857 Using the nbtstat Utility 857 The -a Switch 858 The -A Switch 860 The -c Switch 860 The -n Switch 860 The -r Switch 861 The -R Switch 862 The -S Switch 862 The -s Switch 863 Using the netstat Utility 863 The -a Switch 866 The -e Switch 866 The -r Switch 867 The -s Switch 867 The -p Switch 868 The -n Switch 869 Using tcpdump 871 Examples of Using tcpdump 871 Using the File Transfer Protocol 871 Starting FTP and Logging In to an FTP Server 872 Downloading Files 874 Uploading Files 876 Using the Telnet Utility 876 How to Enable Telnet in Windows 877 Don't Use Telnet, Use Secure Shell 878 Summary 878 Exam Essentials 879 Written Lab 880 Review Questions 881 Appendix A Answers to Written Labs 887 Chapter 1: Introduction to Networks 888 Chapter 2: The Open Systems Interconnection Specifications 888 Chapter 3: Networking Connectors and Wiring Standards 889 Chapter 4: The Current Ethernet Specifications 889 Chapter 5: Networking Devices 891 Chapter 6: Introduction to the Internet Protocol 892 Chapter 7: IP Addressing 893 Written Lab 7.1 893 Written Lab 7.2 893 Chapter 8: IP Subnetting, Troubleshooting IP, and Introduction to NAT 894 Chapter 9: Introduction to IP Routing 895 Chapter 10: Routing Protocols 895 Chapter 11: Switching and Virtual LANs 895 Chapter 12: Wireless Networking 896 Chapter 13: Using Statistics and Sensors to Ensure Network Availability 896 Chapter 14: Organizational Documents and Policies 897 Chapter 15: High Availability and Disaster Recovery 898 Chapter 16: Common Security Concepts 898 Chapter 17: Common Types of Attacks 899 Chapter 18: Network Hardening Techniques 899 Chapter 19: Remote Access Security 900 Chapter 20: Physical Security 900 Chapter 21: Data Center Architecture and Cloud Concepts 901 Chapter 22: Ensuring Network Availability 901 Chapter 23: Cable Connectivity Issues and Tools 902 Chapter 24: Network Troubleshooting Methodology 902 Chapter 25: Network Software Tools and Commands 903 Appendix B Answers to Review Questions 905 Chapter 1: Introduction to Networks 906 Chapter 2: The Open Systems Interconnection Specifications 907 Chapter 3: Networking Connectors and Wiring Standards 909 Chapter 4: The Current Ethernet Specifications 910 Chapter 5: Networking Devices 911 Chapter 6: Introduction to the Internet Protocol 913 Chapter 7: IP Addressing 914 Chapter 8: IP Subnetting, Troubleshooting IP, and Introduction to NAT 916 Chapter 9: Introduction to IP Routing 918 Chapter 10: Routing Protocols 919 Chapter 11: Switching and Virtual LANs 921 Chapter 12: Wireless Networking 922 Chapter 13: Using Statistics and Sensors to Ensure Network Availability 924 Chapter 14: Organizational Documents and Policies 925 Chapter 15: High Availability and Disaster Recovery 926 Chapter 16: Common Security Concepts 927 Chapter 17: Common Types of Attacks 927 Chapter 18: Network Hardening Techniques 928 Chapter 19: Remote Access Security 929 Chapter 20: Physical Security 930 Chapter 21: Data Center Architecture and Cloud Concepts 931 Chapter 22: Ensuring Network Availability 933 Chapter 23: Cable Connectivity Issues and Tools 934 Chapter 24: Network Troubleshooting Methodology 935 Chapter 25: Network Software Tools and Commands 937 Appendix C Subnetting Class A 939 Subnetting Practice Examples: Class A Addresses 940 Practice Example #1A: 255.255.0.0 (/16) 941 Practice Example #2A: 255.255.240.0 (/20) 941 Practice Example #3A: 255.255.255.192 (/26) 942 Subnetting in Your Head: Class A Addresses 942 Written Lab 1 943 Written Lab 2 944 Answers to Written Lab 1 944 Answers to Written Lab 2 945 Index 947