Symbols

* (asterisk), 453

: (colon), 404–405

/8 networks, subnetting, 372–373, 391

10BASE-T, 143

/16 networks, subnetting, 367–370, 391

100BASE-TX, 143

A

A records, 524

AAA (authentication, authorization, and accounting), 555

AAA (authentication, authorization, and accounting)x, 645

AAAA records, 524

access, IOS. See Cisco IOS

access attacks, 548–549

brute-force, 646

definition of, 645

DoS (denial-of-service), 551–552

man-in-the-middle attack, 549

password attacks, 548

port redirection, 549

trust exploitation, 548–549

access control, 35, 216–217

access control lists (ACLs), 35

access methods, definition of, 645

access points (APs), 138, 166, 645

access technologies, 17–20, 92

businesses, 19–20

small office and home offices, 17–19

summary of, 38

ACK (Acknowledgement), 472, 484–486, 488

ACK (Acknowledgment), 645

Acknowledgment (ACK), 645

ACLs (access control lists), 35

address conservation, IPv4, 381–383

address resolution, IPv6 ND (Neighbor Discovery), 311

Address Resolution Protocol. See ARP (Address Resolution Protocol)

addresses

ARP (Address Resolution Protocol)

broadcasts, 307–309

definition of, 301–302

examining with Packet Tracer, 309

maps, 303

overview of, 302–304

replies, 305

requests, 304

role in remote communications, 305–306

spoofing, 307–309

summary of, 313

tables, 306–307

data link, 124, 125, 126–129

devices on same network, 123

IP. See IP (Internet Protocol) addresses

Layer 2, 223–225

Layer 3 logical, 122–123

MAC (media access control), 239–248

address structure, 241–243

address table, 248–254

broadcast, 246–247

destinations on remote network, 299–301

destinations on same network, 298–299

frame processing, 243–244

hexadecimal number system, 240–241

multicast, 247–248

summary of, 313

unicast, 244–245

types of, 121

adjacency tables, 645

ADVERTISE messages, 529

adware, 33

AfriNIC (African Network Information Centre), 358

alternating current, 645

American National Standards Institute (ANSI), 141, 209

American Registry for Internet Numbers (ARIN), 358

American Standard Code for Information Interchange (ASCII), 645

analog telephones, 645

AND, logical, 345–346

ANSI (American National Standards Institute), 141, 209

Anti-Spam Research Group (ASRG), 109

antispyware, 34

antivirus software, 34

anycast, 406, 436–437

APIPA (Automatic Private IP Addressing), 357, 619

APNIC (Asia Pacific Network Information Centre), 358

AppleTalk, 99

application filtering, 557

application layer. See also specific protocols

client-server model, 511–512

definition of, 113, 114, 508

email protocols, 518–521

IMAP (Internet Message Access Protocol), 521

POP (Post Office Protocol), 520

SMTP (Simple Mail Transfer Protocol), 519–520

summary of, 534

file sharing services, 530–533

FTP (File Transfer Protocol), 530

SMB (Server Message Block), 531–533

summary of, 535–536

functions of, 508

IP addressing services, 521–530

DHCP (Dynamic Host Configuration Protocol), 527–529

DNS (Domain Name System), 522–525

nslookup command, 526–527

summary of, 535

overview of, 101–102, 508–511

peer-to-peer applications, 513–515

peer-to-peer networks, 512–513, 534

services in, 579

summary of, 534

web protocols, 515–518

HTML (Hypertext Markup Language), 515–517

HTTP (Hypertext Transfer Protocol), 516–518

HTTPS (HTTP Secure), 516–518

summary of, 534

applications

peer-to-peer, 513–515

small business networks

common applications, 578–579

voice/video applications, 582

summary of, 624

APs (access points), 138, 166, 645

architecture, network, 23

fault tolerance, 24

QoS (quality of service), 25–26

scalability, 24–25

security design, 26–27

ARCNET, 217

ARIN (American Registry for Internet Numbers), 358

ARP (Address Resolution Protocol), 103, 245, 360

broadcasts, 307–309

definition of, 103, 245, 301–302, 360, 645

examining with Packet Tracer, 309

maps, 303

overview of, 302–304

replies, 305

requests, 304

role in remote communications, 305–306

spoofing, 307–309

summary of, 313

tables

displaying, 306–307

removing entries from, 306–307

arp -a command, 307

arp command, 601–602

ASCII (American Standard Code for Information Interchange), 645

Asia Pacific Network Information Centre (APNIC), 358

ASRG (Anti-Spam Research Group), 109

assigned multicast, 646

asterisk (*), 453

asymmetric switching, 646

ATM (Asynchronous Transfer Mode), 225

attacks, 546–552

access, 548–549

brute-force, 646

DoS (denial-of-service), 551–552

man-in-the-middle attack, 549

password attacks, 548

port redirection, 549

trust exploitation, 548–549

malware, 546–547

Trojan horses, 33, 547, 665

viruses, 546

worms, 547, 668

mitigation of, 552–558

AAA (authentication, authorization, and accounting), 555

backups, 553–554

defense-in-depth approach, 553

endpoint security, 558

firewalls, 555–557

summary of, 565

updates and patches, 554

reconnaissance, 547–548, 660

summary of, 565

attenuation, signal, 147

.au domain, 525

authentication, authorization, and accounting (AAA), 555, 645

auto secure command, 558–559

automatic medium-dependent interface crossover (auto-MDIX), 259–260, 646

Automatic Private IP Addressing (APIPA), 357, 619

auto-MDIX, 259–260, 646

AutoSecure, 558–559

availability, data, 27, 646

B

baby giant frames, 238, 646

backups, 553–554

bandwidth, 234

definition of, 646

goodput, 146, 653

latency, 146

throughput, 146, 665

units of, 145

banner messages, 65–66

banner motd command, 65–66, 321, 322

best-effort delivery, 272, 468, 646. See also UDP (User Datagram Protocol)

BGP (Border Gateway Protocol), 103

BIA (burned-in address), 243, 647

binary number systems, 176–194

binary game, 193

binary positional notation, 178–180

binary to decimal conversion, 180–181

decimal to binary conversion

binary positional value tables, 182–186

example of, 186–193

IPv4 addresses, 176–178, 193–194

summary of, 198

binary positional notation, 178–180

binary positional value tables, 182–186

BitTorrent, 514

blocking IPv4 addresses, 356

Bluetooth, 166, 169–170, 646

BOOTP (Bootstrap Protocol), 510, 646

Bootstrap Protocol (BOOTP), 646

Border Gateway Protocol (BGP), 103

bring your own device (BYOD), 28, 646

broadcast addresses, 349, 646

broadcast domains, segmentation and, 359–362

broadcast MAC (media access control) addresses, 246–247

broadcast transmission, 93

ARP (Address Resolution Protocol), 307–309

definition of, 646

IPv4, 350–352, 390

brute-force attacks, 548, 560, 646

buffered memory, 257, 647

burned-in address (BIA), 243, 647

bus topology, 214, 647

businesses. See small business network management

BYOD (bring your own device), 28, 646

C

cable internet connections, 18, 647

cable testers, 647

cabling, copper, 7, 146–152, 168–169

characteristics of, 147–148

coaxial cable, 151–152

fiber-optic cabling versus, 163–164

rollover cables, 157

STP (shielded twisted pair), 150–151, 662

UTP (unshielded twisted pair), 152–158

connectors, 153–156

crossover, 157

definition of, 148–150

properties of, 152–153

standards, 153–156

straight-through, 157

T568A/T68B standards, 157–158

cabling, fiber-optic, 158–164

copper cabling versus, 163–164

definition of, 652

fiber patch cords, 162–163

fiber-optic connectors, 161–162

industry applications of, 160

multimode fiber, 160

properties of, 158–159

single-mode fiber, 159

summary of, 169

CAM (content addressable memory) table, 649

Canadian Standards Association (CSA), 141

Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA), 165–166, 216, 219–220, 647

Carrier Sense Multiple Access/Collision Detect (CSMA/CD), 216, 217–219, 647

categories, UTP cabling, 154

CCNA (Cisco Certified Network Associate) certification, 35–36

CDP (Cisco Discovery Protocol), 609–610

CEF (Cisco Express Forwarding), 647

cellular internet, 18–19, 647

CENELEC (European Committee for Electrotechnical Standardization), 141

certifications, CCNA (Cisco Certified Network Associate), 35–36

CFRG (Crypto Forum Research Group), 109

channels, 87, 647

Checksum field

TCP headers, 472

UDP headers, 474

circuit switched systems, 647

Cisco AutoSecure, 558–559

Cisco Certified Network Associate (CCNA) certification, 35–36

Cisco Discovery Protocol (CDP), 609–610

Cisco Express Forwarding (CEF), 647

Cisco IOS

access, 46–52

access methods, 49–50

GUIs (graphical user interfaces), 47–48

operating systems, 46–47

OSs (operating systems), 48–49

summary of, 79

terminal emulation programs, 50–52

commands, 56–60

basic structure of, 56

hot keys and shortcuts for, 58–60

summary of, 79

syntax of, 57–58

definition of, 648

device configuration, 61–66

banner messages, 65–66

capturing to text file, 68–71

configuration files, 67–68

device names, 61–62, 321

with Packet Tracer, 71

password configuration, 63–64

password encryption, 64–65

password guidelines, 62–63

running configuration, altering, 68

small business network management, 573–574, 624

summary of, 79–80

with Syntax Checker, 66

help, 58

interfaces, 73–74

IP (Internet Protocol) addresses, 618

automatic configuration for end devices, 76–77

manual configuration for end devices, 75–76

structure of, 71–73

summary of, 80

switch virtual interface configuration, 77–78

verification of, 77

navigation, 52–56

configuration mode, 53–54

moving between modes, 54–55

Packet Tracer, 60

primary command modes, 52–53

subconfiguration mode, 53–54

summary of, 79

Syntax Checker, 55–56

Tera Term, 60

ports, 73–74

verifying connectivity of, 78, 80

Cisco Packet Tracer. See Packet Tracer

Cisco routers. See router configuration

Cisco Webex Teams, 29

Class A addresses, 357

Class B addresses, 357

Class C addresses, 357

Class D addresses, 357

Class E addresses, 357

classful addressing, legacy, 357–358, 648

clients

definition of, 4, 648

multicast, 352

UDP (User Datagram Protocol), 495–498

client-server model, 511–512

clock command, 60

cloud computing

definition of, 648

impact on daily life, 4

types of, 29–30

CnC (command-and-control) programs, 551

.co domain, 525

coaxial cable, 151–152, 648

collaboration, 28–29, 648

collision fragments, 238

colon (:), 404–405

.com domain, 525

command modes, Cisco IOS

configuration mode, 53–54

moving between modes, 54–55

primary command modes, 52–53

subconfiguration mode, 53–54

Syntax Checker, 55–56

command syntax check, 58

command-and-control (CnC) programs, 551

command-line interface (CLI). See specific commands

communications, network. See network communications

communities, definition of, 648

community cloud, 30

confidentiality, 27, 648

configuration. See also verification

Cisco IOS devices, 61–66. See also IP (Internet Protocol) addresses

banner messages, 65–66

capturing to text file, 68–71

configuration files, 67–68

device names, 61–62, 321

with Packet Tracer, 71, 336

password encryption, 64–65

password guidelines, 62–64

passwords, 62–65

running configuration, altering, 68

small business network management, 573–574, 624

summary of, 79–80

with Syntax Checker, 66

verifying connectivity of, 78, 80

default gateways, 330–334

on host, 331–332

router connections, 334

on switch, 332–334

with Syntax Checker, 334

default route propagation, 335–336

GUAs (global unicast addresses)

dynamic addressing, 417–425

static, 413–416

IP (Internet Protocol) addresses

automatic configuration for end devices, 76–77

IPv6, 427–430

manual configuration for end devices, 75–76

switch virtual interface configuration, 77–78

IPv4 subnets

/8 networks, 372–373, 391

/16 networks, 367–370, 391

corporate example of, 378–380

DMZ (demilitarized zone), 377

efficiency of, 377–380

maximizing subnets, 377–378

on an octet boundary, 364–366

within an octet boundary, 366–367

with Packet Tracer, 367, 381

private versus public address space, 374–377

summary of, 391–392

unused host IPv4 addresses, minimizing, 377–378

VLSM (variable-length subnet masking), 381–387

IPv6 subnets, 432–435

example of, 433–434

router configuration, 435

subnet allocation, 433–434

subnet IDs, 432–433

LLAs (link-local addresses)

dynamic addressing, 425–430

static, 413–416

password security, 559–561

passwords, 63–64

router interfaces, 323–330

basic configuration, 323–324

dual stack addressing, 324–325

summary of, 335

verification commands, 325–330

routers, 336–337

ARP tables, displaying, 306–307

basic configuration example, 321–323

basic configuration steps, 320–321, 335

default gateways, 330–334

dynamic LLAs (link-local addresses) on, 426–427

host/router communications, 223–225

interfaces, 323–330

switch and router network build, 336–337

SSH (Secure Shell), 561–562

vulnerabilities, 544

configuration mode, 53–54

configure command, 58

configure terminal command, 54, 62, 321, 324

congestion, definition of, 649

congestion avoidance, 493

connected switches, MAC (media access control) address tables on, 252

connectionless, definition of, 649

connectionless IP (Internet Protocol), 271–272

connection-oriented protocols, 468, 649. See also TCP (Transmission Control Protocol)

connectivity, verification of, 586–596

Cisco IOS devices, 78, 80

network baselines, 593–596

ping command, 586–590

summary of, 624

traceroute command, 590–594

tracert command, 590–593

connectors

fiber-optic, 161–162

UTP (unshielded twisted pair) cable, 153–156

console, 49, 649

content addressable memory (CAM) table, 649

contention-based access, 217–220

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance), 216, 219–220

CSMA/CD (Carrier Sense Multiple Access/Collision Detect), 216, 217–219

definition of, 649

contention-based access method, 237

context-sensitive help, 58

Control Bits field (TCP headers), 472

controlled access, 217

converged networks, 20–21, 649

copper cabling, 7, 146–152

characteristics of, 147–148

coaxial cable, 151–152, 648

fiber-optic cabling versus, 163–164

rollover cables, 157

STP (shielded twisted pair), 150–151, 662

summary of, 168–169

UTP (unshielded twisted pair), 152–158

connectors, 153–156

crossover, 157

definition of, 148–150

properties of, 152–153

standards, 153–156

straight-through, 157

summary of, 169

T568A/T68B standards, 157–158

copy running-config startup-config command, 68, 322

core, optical fiber, 649

CRC (cyclic redundancy check), 222–223, 239, 649

crossover UTP cables, 157

crosstalk, 147, 649

Crypto Forum Research Group (CFRG), 109

crypto key generate rsa general-keys modulus command, 561, 562

CSA (Canadian Standards Association), 141

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance), 165–166, 216, 219–220, 647

CSMA/CD (Carrier Sense Multiple Access/Collision Detect), 216, 217–219, 647

custom cloud, 649

cut-through switching, 255–256, 649

cyclic redundancy check (CRC), 222–223, 239, 649

D

DAD (duplicate address detection), 424, 448

daemons, 650

data access, 121–129

data link layer addresses, 124, 125, 126–129

devices on same network, 123

Layer 3 logical addresses, 122–123

overview of, 121

summary of, 132

data availability, 27, 646

data centers, 650

data confidentiality, 27

data encapsulation, 116–121

de-encapsulation, 120–121, 132

example of, 120

IP (Internet Protocol), 270–271

MAC (media access control) sublayer, 236

message segmenting, 116–117

PDUs (protocol data units), 118–120, 132

sequencing, 96, 118–119

summary of, 132

Data field (Ethernet frames), 239

data flow, 6

data integrity, 27, 654

data interception and theft, 33

data link frame, 221–226

frame fields, 222–223

LAN frames, 225–226

Layer 2 addresses, 223–225

overview of, 221

WAN frames, 225–226

data link layer

addresses, 124, 125, 126–129

data link frame, 221–226

frame fields, 222–223

LAN frames, 225–226

Layer 2 addresses, 223–225

overview of, 221

summary of, 229

WAN frames, 225–226

definition of, 114

IEEE 802 LAN/MAN sublayers, 206–207

media access in, 207–208

purpose of, 204–206, 228

standards, 209

topologies, 209–220

access control methods, 216–217

contention-based access, 216–220

controlled access, 217

full-duplex communication, 215–216, 653

half-duplex communication, 215, 653

LAN (local area network), 213–214

physical/logical, 209–211

summary of, 228

WAN (wide area network), 211–213

data link sublayers, 235

data loss, 486–487, 542

data networks, definition of, 650

Data Usage tool, 585

datagrams, 118, 463, 468, 494, 650

debug command, 613–615, 616

debug ip icmp command, 615

debug ip packet command, 615

decapsulation. See de-encapsulation

decimal numbers

binary to decimal conversion, 180–181

decimal positional notation, 178–179

decimal to binary conversion

binary positional value tables, 182–186

example of, 186–193

decimal to hexadecimal conversion, 196

hexadecimal to decimal conversion, 196–197

decoding messages, 89

de-encapsulation, 120–121, 132, 650

default gateways

configuration, 330–334

on host, 331–332

router connections, 334

summary of, 335–336

on switch, 332–334

with Syntax Checker, 334

definition of, 282

host routing to, 282–283

pinging, 450–451

sending frames to, 254

troubleshooting, 334, 619–620

default routes, 650

defense-in-depth approach, 553

delimiting, frame, 207

delivery of messages, 92–93

Deluge, 514

demilitarized zone. See DMZ (demilitarized zone)

denial-of-service (DoS) attacks, 33, 543, 650

description command, 57, 323–324

design, IPv4 structure, 387–389, 392

device address assignment, 389

IPv4 network address planning, 388

with Packet Tracer, 389, 392–393

Destination IPv4 Address field, 276

destination IPv4 addresses, 122, 123, 125, 299

Destination IPv6 Address field, 280

Destination MAC Address field, 238

destination MAC addresses, 124, 126, 243, 299, 301, 305

Destination Port field

TCP headers, 472

UDP headers, 474

destination port numbers, 650

Destination Unreachable messages, 445–446

destinations, definition of, 87

device address assignment, 389

device configuration, 61–66. See also IP (Internet Protocol) addresses

banner messages, 65–66

capturing to text file, 68–71

configuration files, 67–68

device names, 61–62, 321

with Packet Tracer, 71, 336

passwords

configuration, 63–64

encryption, 64–65

guidelines for, 62–63

running configuration, altering, 68

small business network management, 573–574, 624

summary of, 79–80

with Syntax Checker, 66

verifying connectivity of, 78, 80

device identifiers, 422

device security

Cisco AutoSecure, 558–559

passwords, 559–561

SSH (Secure Shell), 561–562

summary of, 566

unused services, disabling, 563–564

DHCP (Dynamic Host Configuration Protocol)

definition of, 101, 651

DHCPv6, 529, 663

dynamic addressing in, 527

IP address configuration with, 75, 360

lease periods, 527–528

operation of, 528–529

overview of, 527–529

pools, 527

port numbers, 479

servers, 581

SLAAC (stateless address autoconfiguration)

stateful DHCPv6, 420–421

and stateless DHCPv6, 419–420

DHCPACK messages, 529

DHCPDISCOVER messages, 528–529

DHCPNAK messages, 529

DHCPOFFER messages, 528–529

DHCPREQUEST messages, 529

diagrams, topology, 8–11

definition of, 10

logical, 10–11

network symbols for, 8–10

physical, 10

dialup internet access, 19

dial-up telephone, 650

DiffServ (DS) field (IPv4), 275

digital cameras, 650

digital subscriber line (DSL), 9, 18

Direct Connect, 514

directed broadcast transmission, 351–352, 651

directly connected networks, 651

disable command, 54

disabling services, 563–564

disruption of service, 543

DMZ (demilitarized zone)

definition of, 651

example of, 354–355

subnetting, 377

DNS (Domain Name System)

definition of, 101, 651

hierarchy, 525

message formats in, 524–525

nslookup command, 526–527, 530

overview of, 510, 522–525

port numbers, 479

servers, 76, 581

troubleshooting, 621–623

domains

broadcast, 359–362

top-level, 525

DoS (denial-of-service) attacks, 33, 543, 551–552, 650

dotted decimal notation

binary to decimal conversion, 180–181

decimal positional notation, 178–179

decimal to binary conversion

binary positional value tables, 182–186

example of, 186–193

decimal to hexadecimal conversion, 196

hexadecimal to decimal conversion, 196–197

double colon (::), 404–405

downloads, 512

DS (DiffServe) field (IPv4), 275

DSL (digital subscriber line), 9, 18, 650

dual stack addressing, 324–325, 399–400, 651

duplex multimode LC (Lucent Connector) connectors, 162, 651

duplex operation

definition of, 651

settings for, 257–259

troubleshooting, 617

duplicate address detection (DAD), 424, 448

dynamic addressing, 527

for GUAs (global unicast addresses), 417–425, 437

EUI-64 process, 422–424

randomly generated interface IDs, 424–425

RS and RA messages, 417–418

SLAAC and stateless DHCPv6, 419–420

stateful DHCPv6, 420–421

for LLAs (link-local addresses), 425–430, 437–438

dynamic LLA creation, 425

dynamic LLA on Cisco routers, 426–427

dynamic LLA on Windows, 425–426

IPv6 address configuration, verification of, 427–430

with Packet Tracer, 430

Dynamic Host Configuration Protocol. See DHCP (Dynamic Host Configuration Protocol)

dynamic routing, 288–290

dynamic routing protocols, 651. See also specific protocols

E

Echo Reply messages, 444–445

Echo Request messages, 444–445

eDonkey, 514

EHs (extension headers), 280

EIA (Electronic Industries Alliance), 111

EIGRP (Enhanced Interior Gateway Routing Protocol), 103

electrical threats, 545

electromagnetic interference (EMI), 147, 651

Electronic Industries Alliance (EIA), 111

electronic standards, 111

email protocols, 518–521

IMAP (Internet Message Access Protocol), 521

POP (Post Office Protocol), 520

SMTP (Simple Mail Transfer Protocol), 519–520

summary of, 534

email servers, 5, 581

EMI (electromagnetic interference), 147, 651

employee network utilization, 584–586

enable command, 54

enable passwords, 651

enable secret, 64, 320, 322, 651

encapsulation, 116–121

de-encapsulation, 120–121, 132

definition of, 651

Ethernet frames, 234–235

example of, 120

IP (Internet Protocol), 270–271

MAC (media access control) sublayer, 236

message segmenting, 116–117

messages, 90–91

PDUs (protocol data units), 118–120, 132

sequencing, 96, 118–119

summary of, 132

encoding, 88–89, 142–143, 651

encryption, password, 64–65

end command, 55

end devices. See hosts

endpoint security, 558

Enhanced Interior Gateway Routing Protocol (EIGRP), 103

enterprise networks, 160

environmental threats, 545

erase startup-config command, 68

error detection, 96, 207, 222–223

escalation, 613

EtherChannel, 651

Ethernet, 254–255

bandwidths, 234

crossover, 157

definition of, 103, 652

encoding, 143

frames, 234–239

baby giant frames, 238, 646

data link sublayers, 235

encapsulation, 234–235

fields in, 237–239

filtering, 252–253

forwarding methods, 254–255, 262

jumbo frames, 238, 655

MAC sublayer, 236–237

runt frames, 238, 661

sending to default gateway, 254

summary of, 261

Gigabit, 323

hubs, 7

MAC (media access control) addresses, 239–248

address structure, 241–243

address table, 248–254, 261

broadcast, 246–247

frame processing, 243–244

hexadecimal number system, 240–241

multicast, 247–248

summary of, 261

unicast, 244–245

Metro Ethernet, 18, 20

straight-through, 157

switches

Auto-MDIX, 259–260

cut-through switching, 255–256, 649

duplex settings, 257–259

fast-forward switching, 256, 652

fragment-free switching, 256, 652–653

frame filtering, 252–253

frame forwarding methods on, 254–255

learning and forwarding, 248–249

memory buffering on, 257

overview of, 248–249

speed settings, 257–259, 262

store-and-forward switching, 254–255, 664

ETSI (European Telecommunications Standards Institute), 141

EUI-64 process, 422–424, 652

EUIs (Extended Unique Identifiers), 422–424

European Committee for Electrotechnical Standardization, 141

European Telecommunications Standards Institute (ETSI), 141

EXEC mode, 53, 666

exec-timeout command, 561

Exit and Logout command (Packet Tracer), 22

exit command, 54–55

expandability, small business networks, 573

expectational acknowledgement, 488, 652

Extended Unique Identifiers (EUIs), 422–424, 652

extension headers (EHs), 280

extranets, 16–17, 652

F

fast-forward switching, 256, 652

fault tolerance, 24, 652

FCC (Federal Communications Commission), 141

FCS (Frame Check Sequence) field, 222–223, 239

FDDI (Fiber Distributed Data Interface), 214

Federal Communications Commission (FCC), 141

ff02::1 all-nodes multicast group, 431

ff02::2 all-routers multicast group, 431

FIB (Forwarding Information Base), 652

Fiber Distributed Data Interface (FDDI), 214

fiber patch cords, 162–163

fiber-optic cabling, 7, 158–164

copper cabling versus, 163–164

definition of, 652

fiber patch cords, 162–163

fiber-optic connectors, 161–162

industry applications of, 160

multimode fiber, 160

properties of, 158–159

single-mode fiber, 159

summary of, 169

fiber-optic connectors, 161–162

fiber-to-the-home (FTTH), 160

fields

data link frame, 222–223

Ethernet frame, 237–239

IPv4 packets, 274–276

IPv6 packets, 280–281

TCP headers, 472

UDP headers, 474

file servers, 5

file sharing services, 530–533

FTP (File Transfer Protocol), 530

SMB (Server Message Block), 531–533

summary of, 535–536

File Transfer Protocol (FTP), 101, 511, 581. See also file sharing services

files, configuration, 67–68

filtering

frame, 252–253

URLs (uniform resource locators), 557

FIN flag, 486

Finish (FIN) control flag, 484–485

firewalls, 34, 555–557

definition of, 652

firmware, 48

flags, 486

flow control, 92, 471, 490–494, 652

Flow Label field (IPv6), 280

formatting messages, 90–91

form-factor pluggable (SFP) devices, 161

forwarding, 248–249, 254–255, 262, 281–282, 285–286

Forwarding Information Base (FIB), 652

fping command, 547

FQDNs (fully qualified domain names), 522

fragment-free switching, 256, 652–653

fragmenting packets, 274, 652

Frame Check Sequence (FCS) field, 222–223, 239

Frame Relay, 225

frames

data link, 221–226

frame fields, 222–223

LAN frames, 225–226

Layer 2 addresses, 223–225

overview of, 221

summary of, 229

WAN frames, 225–226

delimiting, 207

Ethernet, 234–239

baby giant frames, 238, 646

data link sublayers, 235

encapsulation, 234–235

fields in, 237–239

forwarding methods, 254–255, 262

jumbo frames, 238, 655

MAC sublayer, 236–237

runt frames, 238, 661

sending to default gateway, 254

summary of, 261

filtering, 252–253

MAC (media access control) addresses, 243–244

Freenet, 514

FTP (File Transfer Protocol), 101, 479, 511, 530, 581

definition of, 652

FTPS (FTP Secure), 581

FTTH (fiber-to-the-home), 160

full-duplex communication, 215–216, 617, 653

fully qualified domain names (FQDNs), 522

G

gateways, default

configuration, 330–334

on host, 331–332

router connections, 334

summary of, 335–336

on switch, 332–334

with Syntax Checker, 334

definition of, 282

host routing to, 282–283

pinging, 450–451

sending frames to, 254

troubleshooting, 334, 619–620

gateways, definition of, 653

Gbps (gigabits per second), 145

GET requests, 516

GIF (Graphics Interchange Format), 509

Gigabit Ethernet, 323

gigabits per second (Gbps), 145

global configuration mode, 53, 653

global routing prefix, 410, 653

global unicast addresses. See GUAs (global unicast addresses)

Gnutella, 514

goodput, 146, 653

gping command, 547

graphical user interfaces (GUIs), 47–48, 653

Graphics Interchange Format (GIF), 509

groups, port number, 478

GUAs (global unicast addresses)

definition of, 408

dynamic addressing for, 417–425, 437

EUI-64 process, 422–424

randomly generated interface IDs, 424–425

RS and RA messages, 417–418

SLAAC and stateless DHCPv6, 419–420

stateful DHCPv6, 420–421

static configuration of, 413–416

structure of, 408–411

summary of, 437

GUIs (graphical user interfaces), 47–48, 653

H

half-duplex communication, 215, 617, 653

hardware, 47

hardware threats, 545

HDLC (High-Level Data Link Control), 225

Header Checksum field (IPv4 packets), 275

Header Length field (TCP headers), 472

headers

IPv4 (Internet Protocol version 4), 274–276

IPv6 (Internet Protocol version 6), 278–281

TCP (Transmission Control Protocol), 471–472

UDP (User Datagram Protocol), 474

help, Cisco IOS, 58

hexadecimal number systems, 194–197, 240–241

decimal to hexadecimal conversion, 196

definition of, 653

hexadecimal to decimal conversion, 196–197

IPv6 addresses, 194–196

summary of, 198

hextets, 653

High-Level Data Link Control (HDLC), 225

Hop Limit field (IPv6 packets), 280

hops, 269

host commands, for small business networks, 596–611. See also specific commands

IP configuration on Linux hosts, 599–600

IP configuration on MacOS hosts, 596–601

IP configuration on Windows hosts, 596–598

summary of, 625–626

hostname command, 62, 320, 321

hosts

Cisco IOS. See Cisco IOS

default gateway configuration on, 331–332

definition of, 6

host addresses, 348, 653

host commands, 596–611. See also specific commands

IP configuration on Linux hosts, 599–600

IP configuration on MacOS hosts, 596–601

IP configuration on Windows hosts, 596–598

summary of, 625–626

host communication, 281–284

default gateways, host routing to, 282–283

host forwarding decisions, 281–282

host/router communications, 223–225

routing tables, 283–284

IP addresses. See IP (Internet Protocol) addresses

Linux, 599–600

MacOS, 596–601

pinging, 451–452

reachability, 444–445

remote, 282

roles of, 4–5

Windows, 596–598

hot keys, 58–60

HTTP (Hypertext Transfer Protocol), 102, 479, 511, 516–518, 580

definition of, 653

HTTPS (HTTP Secure), 102, 479, 511, 515–518, 580

definition of, 653

hub-and-spoke topologies, 211–212

hubs, 653

hubs, Ethernet, 7

hybrid cloud, 30, 654

Hypertext Transfer Protocol (HTTP), 102, 479, 511, 516–518, 580

I

IAB (Internet Architecture Board), 16, 109

IANA (Internet Assigned Numbers Authority), 109, 358, 654

ICANN (Internet Corporation for Assigned Names and Numbers), 16, 109

ICMP (Internet Control Message Protocol)

definition of, 102, 654

messages, 444–448

Destination Unreachable, 445–446

Echo Reply, 444–445

Echo Request, 444–445

Neighbor Advertisement (NA), 446–448

Neighbor Solicitation (NS), 446–448

Router Advertisement (RA), 446–448

Router Solicitation (RS), 446–448

summary of, 454

Time Exceeded, 446

ping tests, 449–452, 455

default gateways, 450–451

loopback addresses, 450

remote hosts, 451–452

summary of, 454–455

testing network connectivity with, 455

traceroute tests, 452–455

identity theft, 33, 543

IDs

device, 422

interface, 410–411

interface IDs, 424, 654

interfaces, 654

randomly generated interface IDs, 424–425

subnet, 410, 432–433, 664

IEEE (Institute of Electrical and Electronics Engineers), 111, 141, 209

definition of, 654

IEEE 802 LAN/MAN sublayers, 206–207

wireless standards, 165–166, 169–170

IETF (Internet Engineering Task Force), 16, 98, 109, 141, 209

ifconfig command, 596–601

IMAP (Internet Message Access Protocol), 101, 479, 510, 521, 581, 654

INFORMATION REQUEST messages, 529

information theft, 542

initial sequence number (ISN), 487, 654

installation, Packet Tracer, 21–22

Institute of Electrical and Electronics Engineers. See IEEE (Institute of Electrical and Electronics Engineers)

Integrated Services Digital Network (ISDN), 654

integrity, data, 27, 654

interface command, 323

interface configuration mode, 54

interface IDs, 410–411, 424, 654

interface vlan 1 command, 77

interfaces

Cisco IOS, 73–74

configuration, 323–330

basic configuration, 323–324

dual stack addressing, 324–325

summary of, 335

verification commands, 325–330

definition of, 9, 654

loopback, 356

randomly generated interface IDs, 424–425

selection of, 573

switch virtual interfaces, 77–78

intermediary devices, 6–7, 654

International Organization for Standardization (ISO), 98, 141, 209, 654

International Telecommunication Union (ITU), 98, 141, 209, 654

International Telecommunications Union-Telecommunication Standardization Sector (ITU-T), 111

internet

definition of, 15–16, 654

impact on daily life, 3–4

internet access technologies for, 17–20

businesses, 19–20

small office and home offices, 17–19

summary of, 38

standards, 109

Internet Architecture Board (IAB), 16, 109

Internet Assigned Numbers Authority (IANA), 109, 358, 654

Internet Control Message Protocol. See ICMP (Internet Control Message Protocol)

Internet Corporation for Assigned Names and Numbers (ICANN), 16, 109

Internet Engineering Task Force (IETF), 16, 98, 109, 141, 209

internet layer, 102–103, 114

Internet Message Access Protocol (IMAP), 101, 479, 510, 521, 581, 654

Internet of Things (IoT), 166, 399

internet queries, 655

Internet Research Task Force (IRTF), 109

internet service providers (ISPs), 9, 655

Internet Society (ISOC), 109

Internetwork Operating System. See Cisco IOS

intranets, 16–17, 655

intrusion detection system (IDS), 655

intrusion prevention systems (IPSs), 35, 655

IOS. See Cisco IOS

IoT (Internet of Things), 166, 399

IP (Internet Protocol) addresses, 91, 102, 398–401

ARP (Address Resolution Protocol)

broadcasts, 307–309

definition of, 301–302

examining with Packet Tracer, 309

maps, 303

overview of, 302–304

replies, 305

requests, 304

role in remote communications, 305–306

spoofing, 307–309

summary of, 313

tables, 306–307

automatic configuration for end devices, 76–77

characteristics of, 271

best-effort delivery, 272

connectionless, 271–272

media independence, 273–274

configuration

on Linux hosts, 599–600

on Windows hosts, 596–598

definition of, 4

destinations on remote network, 299–301

destinations on same network, 298–299

encapsulation, 270–271

IP addressing services, 521–530

DHCP (Dynamic Host Configuration Protocol), 527–529

DNS (Domain Name System), 522–525

nslookup command, 526–527

summary of, 535

IPv4. See IPv4 (Internet Protocol version 4) addressing

IPv6. See IPv6 (Internet Protocol version 6) addressing

loopback, pinging, 450

manual configuration for end devices, 75–76

overview of, 122–123

small business networks, 574–576

structure of, 71–73

summary of, 80, 313

switch virtual interface configuration, 77–78

troubleshooting

on end devices, 619

on IOS devices, 618

verification of, 77

VoIP (voice over IP), 469, 582

ip address command, 77, 323, 413, 600

ip default-gateway command, 77, 333

ip default-gateway ip-address command, 335–336

ip domain name command, 561

IP telephony, 582

ipconfig /all command, 622

ipconfig command, 77, 78, 423–426, 596–598, 620

ipconfig /displaydns command, 525

IPSs (intrusion prevention systems), 35, 655

IPv4 (Internet Protocol version 4) addressing, 72, 102

address conservation, 381–383

address structure, 342–349

broadcast addresses, 349

host addresses, 348

host portion, 342

logical AND, discovering addresses with, 345–346

network addresses, 347–348, 657

network portion, 342

prefix length, 344–345

subnet mask, 343–344

summary of, 390

assignment of, 358–359

binary number systems, 176–178

broadcast, 350–352, 390

coexistence with IPv6, 399+0095

dual stack addressing, 399–400

translation, 400–401

tunneling, 400

definition of, 655

destination addresses, 299

directed broadcast, 351–352, 651

DMZ (demilitarized zone), 354–355

limitations of, 398–401, 436

multicast, 352–353, 390

network segmentation, 359–362

broadcast domains and, 359–362

reasons for, 362

summary of, 391

number systems, 193–194

overview of, 342

packets, 274–276

fragmenting, 274

header fields, 274–276

headers, 274

limitations of, 277

summary of, 292

passing/blocking, 356

routing tables, 290–291

routing to Internet, 354

for small business networks, 574–576

source addresses, 299

structured design, 387–389, 392

device address assignment, 389

IPv4 network address planning, 388

with Packet Tracer, 389, 392–393

subnetting, 364–381. See also VLSM (variable-length subnet masking)

/8 networks, 372–373, 391

/16 networks, 367–370, 391

corporate example of, 378–380

DMZ (demilitarized zone), 377

efficiency of, 377–380

maximizing, 377–378

on an octet boundary, 364–366

within an octet boundary, 366–367

with Packet Tracer, 367, 381

private versus public address space, 374–377

summary of, 391–392

unused host IPv4 addresses, minimizing, 377–378

types of

legacy classful, 357–358, 648

link-local, 357

loopback, 356

private, 353–354

public, 353–354

summary of, 390

unicast, 349–350, 390

VLSM (variable-length subnet masking), 381–387

address conservation, 381–383

network address assignments in, 386–387

overview of, 381

subnetting schemes in, 383–385

summary of, 392

IPv6 (Internet Protocol version 6) addressing, 73, 102, 408

address formats, 401–406, 436

double colon (::), 404–405

leading zeros, 403–404

preferred format, 402

anycast, 406, 436–437

coexistence with IPv4, 399–401

dual stack addressing, 399–400

translation, 400–401

tunneling, 400

GUAs (global unicast addresses)

definition of, 408

dynamic addressing for, 417–425, 437

static configuration of, 413–416

structure of, 408–411

summary of, 437

LLAs (link-local addresses)

definition of, 408

dynamic addressing for, 425–430, 437–438

static configuration of, 413–416

structure of, 411–412

summary of, 437

multicast

characteristics of, 93, 406, 430–432, 436–437

solicited-node, 432

summary of, 438

well-known, 430–431

ND (Neighbor Discovery), 309–312, 314

address resolution, 311

examining with Packet Tracer, 312

messages, 309–310

summary of, 314

need for, 398–401, 436

number systems, 194–196

packets, 277–281

headers, 278–281

overview of, 277–278

prefix length, 406–407

subnetting, 432–435

example of, 433–434

with Packet Tracer, 438

router configuration, 435

subnet allocation, 434–435

subnet IDs, 432–433

summary of, 438

unicast, 406, 407–408, 436–437

verifying configuration of, 427–430

ipv6 address command, 323, 413–414

ipv6 address link-local command, 415–416

ipv6 unicast-routing command, 418, 431

IRFT (Internet Research Task Force), 109

ISD (intrusion detection system), 655

ISDN (Integrated Services Digital Network), 654

ISN (initial sequence number), 487, 654

ISO (International Organization for Standardization), 98, 141, 209, 654

ISOC (Internet Society), 109

ISPs (internet service providers), 9, 655

IT professionals, 35–36, 40

CCNA certification for, 35–36

networking jobs for, 36

ITU (International Telecommunication Union), 98, 111, 141, 209, 654

J

jackets, 655

Japanese Standards Association (JSA/JIS), 141

JPG (Joint Photographic Experts Group), 509

JSA/JIS (Japanese Standards Association), 141

jumbo frames, 238, 655

K

kbps (kilobits per second), 145

kernel, 47, 655

keyboard shortcuts, 58–60

kilobits per second (kbps), 145

L

LACNIC (Regional Latin-American and Caribbean IP Address Registry), 359

LANs (local area network), 12–14. See also network communications; networks; router configuration

definition of, 655

IEEE 802 LAN/MAN sublayers, 206–207

LAN frames, 225–226

topologies, 213–214

latency, 146, 655

Layer 2 addresses, 223–225

Layer 3 logical addresses, 122–123

layered security, 553

layers, OSI model. See OSI (Open System Interconnection) model

layers, TCP/IP model. See TCP/IP (Transmission Control Protocol/Internet Protocol) model

LC (Lucent Connector) connectors, 162

LDAP (Lightweight Directory Access Protocol), 655

leading zeros

double colon (::), 404–405

in IPv6 addresses, 403–404

learning, switch, 248–249

lease periods, 527–528

leased lines, 18, 19

legacy classful addressing, 357–358, 648

legacy LAN topologies, 214

Length field (UDP headers), 474

Lightweight Directory Access Protocol (LDAP), 655

limited broadcast, 655

line console 0 command, 63

line of sight wireless, 655

line vty 0 15 command, 64

Link Layer Discovery Protocol (LLDP), 247

link-local addresses. See LLAs (link-local addresses)

Linux hosts, IP (Internet Protocol) configuration on, 599–600

LLAs (link-local addresses), 357

definition of, 408, 655

dynamic addressing for, 425–430, 437–438

dynamic LLA creation, 425

dynamic LLA on Cisco routers, 426–427

dynamic LLA on Windows, 425–426

IPv6 address configuration, verification of, 427–430

with Packet Tracer, 430

static configuration of, 413–416

structure of, 411–412

summary of, 437

LLC (Logical Link Control), 206, 235, 656

LLDP (Link Layer Discovery Protocol), 247

local area networks. See LANs (local area network)

AND, logical, 645

logical addresses. See IP (Internet Protocol) addresses

logical AND, 345–346, 645

Logical Link Control (LLC), 206, 235, 656

logical NOT, 345

logical OR, 345

logical topologies, 10–11, 209–211

logical topology diagrams, 656

login block-for command, 560

login command, 63, 64

login local command, 562

long-haul networks, 160

loopback adapters, 656

loopback addresses, 356, 450, 656

loopback interfaces, 656

loopback interfaces, pinging, 356

LTE, 656

Lucent Connector (LC) connectors, 162

M

MAC (media access control) addresses, 124, 206–207, 239–248

address structure, 241–243

address table, 248–254

on connected switches, 252

definition of, 656

frame filtering, 252–253

summary of, 261

switch fundamentals, 248–249

switch learning and forwarding, 250–251

viewing, 254

ARP (Address Resolution Protocol)

broadcasts, 307–309

definition of, 301–302

examining with Packet Tracer, 309

overview of, 302–304

replies, 305

requests, 304

role in remote communications, 305–306

spoofing, 307–309

summary of, 313

tables, 306–307

broadcast, 246–247

definition of, 656

destinations on remote network, 299–301

destinations on same network, 298–299

frame processing, 243–244

hexadecimal number system, 240–241

multicast, 247–248

summary of, 261, 313

unicast, 244–245

MAC (media access control) sublayer, 236–237. See also MAC (media access control) addresses

data encapsulation, 236

media access, 237

MacOS hosts, IP configuration on, 596–601

maintenance threats, 545

malware, 546–547

Trojan horses, 33, 547, 665

viruses, 546

worms, 547, 668

Manchester encoding, 142–143

man-in-the-middle attack, 549

MANs (metropolitan-area networks), 656

maps (ARP), 303

Matroska Video (MKV), 509

maximizing subnets, 377–378

maximum segment size (MSS), 491–492

maximum transmission unit (MTU), 492, 656

Mbps (megabits per second), 145

mdix auto command, 259

media, network, 7–8

media access

data link layer functions, 207–208

MAC (media access control) sublayer, 237

media access control. See MAC (media access control) addresses

media independence, 273–274, 656

megabits per second (Mbps), 145

memory buffering, 257, 647

mesh topologies, 212

messages. See also data encapsulation

banner, 65–66

decoding, 89

delivery options for, 92–93

destinations, 87

DHCP (Dynamic Host Configuration Protocol), 528–529

DNS (Domain Name System), 524–525

encapsulating, 90–91

encoding, 88–89, 142–143

formatting, 90–91

ICMP (Internet Control Message Protocol), 444–448

Destination Unreachable, 445–446

Echo Reply, 444–445

Echo Request, 444–445

Neighbor Advertisement (NA), 446–448

Neighbor Solicitation (NS), 446–448

Router Advertisement (RA), 446–448

Router Solicitation (RS), 446–448

summary of, 454

Time Exceeded, 446

ND (Neighbor Discovery), 309–310

segmenting, 116–117

size of, 91–92

sources, 87

timing, 92–93

Metro Ethernet, 18, 20

metropolitan-area networks (MANs), 656

mismatch issues, troubleshooting, 617

mitigation techniques, 552–558

AAA (authentication, authorization, and accounting), 555

backups, 553–554

defense-in-depth approach, 553

endpoint security, 558

firewalls, 555–557

summary of, 565

updates and patches, 554

MKV (Matroska Video), 509

MMF (multimode fiber), 160, 657

models. See OSI (Open System Interconnection) model; TCP/IP (Transmission Control Protocol/Internet Protocol) model

modems, 656

Motion Picture Experts Group (MPG), 509

MOV (QuickTime Video), 509

MPG (Motion Picture Experts Group), 509

MSS (maximum segment size), 491–492

MTU (maximum transmission unit), 492, 656

multiaccess networks, 216

multicast IPv4 addresses, 352–353, 390

multicast IPv6 addresses

assigned multicast, 646

characteristics of, 93, 406, 430–432, 436–437

solicited-node, 432

summary of, 438

well-known, 430–431, 667

multicast MAC (media access control) addresses, 247–248

multicast transmission, 656–657

multimeters, 657

multimode fiber (MMF), 160, 657

multiplexing, 117–118, 132, 657

MX records, 524

N

NA (Neighbor Advertisement) message, 309, 446–448, 657

names, Cisco IOS device, 61–62

NAS (network attached storage), 657

NAT (Network Address Translation), 354, 398, 657

NAT64 (Network Address Translation 64), 400–401

navigation, Cisco IOS, 52–56

configuration mode, 53–54

moving between modes, 54–55

Packet Tracer, 60

primary command modes, 52–53

subconfiguration mode, 53–54

summary of, 79

Syntax Checker, 55–56

Tera Term, 60

ND (Neighbor Discovery), 245, 309–312, 446

address resolution, 311

definition of, 657

examining with Packet Tracer, 312

messages, 309–310

summary of, 314

Neighbor Advertisement (NA) messages, 309, 446–448, 657

Neighbor Discovery. See ND (Neighbor Discovery)

Neighbor Solicitation (NS) messages, 309, 446–448, 657

netsh interface ip delete arpcache command, 602

netstat command, 479–480

netstat -r command, 283–284, 293

NetWare, 99

network access layer, 103, 114

Network Address Translation 64 (NAT64), 400–401

Network Address Translation (NAT), 354, 398, 657

network addresses, 347–348, 657

network applications, 578

network architecture, definition of, 657

network attached storage (NAS), 657

network baselines, 593–596

network communications. See also OSI (Open System Interconnection) model; TCP/IP (Transmission Control Protocol/Internet Protocol) model

communications standards, 111

data access, 121–129

data link addresses, 124, 126–129

devices on same network, 123

Layer 3 logical addresses, 122–123

network layer addresses, 125

overview of, 121

summary of, 132

data encapsulation, 116–121

de-encapsulation, 120–121, 132

example of, 120

message segmenting, 116–117

PDUs (protocol data units), 118–120, 132

sequencing, 96, 118–119

summary of, 132

definition of, 648

messages

decoding, 89

delivery options for, 92–93

destination, 87

encapsulating, 90–91

encoding, 88–90, 142–143

formatting, 90–91

segmenting, 96, 118–119

size of, 91–92

sources, 87

timing, 92–93

overview of, 86–87, 88

protocol suites, 97–107. See also TCP/IP (Transmission Control Protocol/Internet Protocol) model

evolution of, 98–99

overview of, 97–98

summary of, 130

protocols. See also specific protocols

definition of, 87–88

functions of, 95–96

interaction between, 96

requirements of, 88–89

summary of, 130

types of, 94–95

rule establishment for, 88, 130

standards organizations, 108–111

communications standards, 111

electronic standards, 111

internet standards, 109

open standards, 108–109

summary of, 131

network infrastructure, definition of, 657

network interface cards (NICs), 9, 139, 168, 657

network layer. See also IP (Internet Protocol) addresses

basic operations of, 268–269

characteristics of, 268–274, 292

hops, 269

host communication, 281–284

default gateways, 282–283

host forwarding decisions, 281–282

routing tables, 283–284

routing, 285–291

dynamic, 288–290

IP router routing tables, 286–287

IPv4 routing tables, 290–291

router packet forwarding decisions, 285–286

static, 287–288

networking jobs, 36

networks. See also addresses; internet; network communications; router configuration; small business network management

architecture of, 23

BYOD (bring your own device), 28

clients, 4

cloud computing, 29–30

collaboration, 28–29, 648

connectivity, testing

with Packet Tracer, 455

with ping tests, 455

with traceroute, 455

converged, 20–21, 649

data flow through, 6

end devices, 6

extranets, 16–17, 652

host roles, 4–5

impact on daily life, 3–4, 37

intermediary devices, 6–7

intranets, 16–17

LAN (local area network) design, 12–14. See also router configuration

IEEE 802 LAN/MAN sublayers, 206–207

LAN frames, 225–226

topologies, 213–214

media, 7–8

peer-to-peer, 5, 658

powerline networking, 31–32

prefixes, 345

reliability of, 23–27

fault tolerance, 24

QoS (quality of service), 25–26

scalability, 24–25

security design, 26–27

summary of, 38

remote, 661

representations of, 8–10, 37

role of IT professionals in, 35–36, 40

security, 33–35, 542–543

attack mitigation, 552–558

attacks, 546–552

design for, 26–27

device, 558–564, 566

mitigation techniques, 34–35

physical, 545–546

summary of, 39

threats, 33–34, 565

vulnerabilities, 543–544

segmentation of, 359–362

broadcast domains and, 359–362

definition of, 662

reasons for, 362

summary of, 391

servers

common software for, 4–5

definition of, 4

sizes of, 11–12

smart homes, 31

SOHO (small office and home office) networks, 12

topology diagrams for, 8–11

definition of, 10

logical, 10–11

network symbols for, 8–10

physical, 10

trends in, 27–32, 38–39

types of, 37

video communications tools for, 29

WANs (wide area networks), 14–15

wireless, 32

networksetup -getinfo command, 601

networksetup -listallnetworkservices command, 601

Next Header field (IPv6 packets), 280

next hop, 657

nibble boundary, 657

NICs (network interface cards), 9, 139, 168, 657

no hostname command, 62

no ip directed-broadcasts command, 352

no ip http server command, 563

no shutdown command, 77, 323–324, 335

node icon, 94

noise, 658

nonreturn to zero (NRZ), 658

Non-Volatile Memory Express (NVMe), 658

nonvolatile random-access memory (NVRAM), 67, 658

notation, positional. See positional notation

Novell NetWare, 99

NRZ (nonreturn to zero), 658

NS (Neighbor Solicitation) message, 309, 446–448, 657

NS records, 524

nslookup command, 526–527, 530, 547, 622–623, 658

number systems

binary, 176–194

binary positional notation, 178–180

binary to decimal conversion, 180–181

decimal to binary conversion, 182–193

IPv4 addresses, 176–178

summary of, 198

hexadecimal, 194–197

decimal to hexadecimal conversion, 196

hexadecimal to decimal conversion, 196–197

IPv6 addresses, 194–196

summary of, 198

653, 653

overview of, 176

numbers, port

definition of, 465

destination, 650

groups of, 478

multiple separation communications with, 476

netstat command, 479–480

socket pairs, 477–478

well-known, 479

NVMe (Non-Volatile Memory Express), 658

NVRAM (nonvolatile random-access memory), 67, 658

O

octet boundary, 658

subnetting on, 364–366

subnetting within, 366–367

octets, 658

Open Samples command (Packet Tracer), 22

Open Shortest Path First (OSPF), 103

open standards, 108–109

Open System Interconnection model. See OSI (Open System Interconnection) model

OpenDNS, 622

operating systems (OSs), 46–47, 48–49

optical fiber cabling. See fiber-optic cabling

OR, logical, 345

.org domain, 525

organizationally unique identifiers (OUIs), 242, 422, 658

OSI (Open System Interconnection) model, 508. See also TCP/IP (Transmission Control Protocol/Internet Protocol) model

application layer

client-server model, 511–512

definition of, 508

email protocols, 518–521

file sharing services, 530–533

IP addressing services, 521–530

peer-to-peer applications, 513–515

peer-to-peer networks, 512–513

protocols, 508–511

purpose of, 508

summary of, 534

web protocols, 515–518

benefits of using, 112

data link layer

data link frame, 221–226, 229

IEEE 802 LAN/MAN sublayers, 206–207

media access in, 207–208

purpose of, 204–206, 228

standards, 209

topologies, 209–220, 228

definition of, 98

network layer. See also IP (Internet Protocol) addresses

basic operations of, 268–269

characteristics of, 268–274, 292

hops, 269

host communication, 268–269

routing, 285–291

overview of, 112–114

Packet Tracer simulation, 116

physical layer. See also copper cabling; fiber-optic cabling

characteristics of, 141–146, 168

fiber-optic cabling, 158–164

purpose of, 138–140

summary of, 168

wireless media, 164–167, 169–170

summary of, 131

TCP/IP model compared to, 115–116

OSPF (Open Shortest Path First), 103

OSs (operating systems), 46–47, 48–49

OUIs (organizationally unique identifiers), 242, 422, 658

out-of-band management, 49

overhead, 658

P

P2P (peer-to-peer) applications, 513–515

P2P (peer-to-peer) networks, 5, 512–513, 534, 658

P2PRG (Peer-to-Peer Research Group), 109

packet filtering, 557

packet forwarding. See forwarding

packet switched. See switches

Packet Tracer

ARP table examination with, 309

Cisco IOS navigation with, 60

connecting routers with, 334

device configuration with, 71, 336

features of, 22–23

installation of, 21–22

IPv6 addressing configuration with, 430

IPv6 ND examination with, 312

IPv6 subnetting with, 438

physical layer connections with, 167

reference model simulations, 116

router configuration with, 323

subnetting with, 367, 381

testing network connectivity with, 455

VLSM design and implementation, 389, 392–393

packets

fragmenting, 274, 652

IPv4, 274–276

header fields, 274–276

headers, 274

limitations of, 277

summary of, 292

IPv6, 277–281

headers, 278–281

IPv6 packets, 277–278

router forwarding decisions, 285–286

PANs (personal-area networks), 658

parallel ports, 658

passing IPv4 addresses, 356

passphrases, 560

password attacks, 548

password command, 63, 64, 320

passwords

Cisco IOS devices

configuration, 63–64

encryption, 64–65

guidelines for, 62–63

configuration of, 559–561

enable, 651

SSH (Secure Shell), 561–562

patches, 554

Payload Length field (IPv6 packets), 280

PDUs (protocol data units), 118–120, 132, 660

peers, 512

peer-to-peer applications, 513–515

peer-to-peer networks, 5, 512–513, 534, 658

Peer-to-Peer Research Group (P2PRG), 109

personal-area network (PAN), 658

physical addresses. See MAC (media access control) addresses

physical layer

characteristics of, 141–146

bandwidth, 145–146

components, 142

encoding, 142–143

signaling, 143–144

standards organizations, 141

summary of, 168

copper cabling, 146–152

characteristics of, 147–148

coaxial cable, 151–152, 648

fiber-optic cabling versus, 163–164

rollover cables, 157

STP (shielded twisted pair), 150–151

summary of, 168–169

UTP (unshielded twisted pair), 148–150, 152–158, 169

definition of, 114

fiber-optic cabling, 158–164

copper cabling versus, 163–164

fiber patch cords, 162–163

fiber-optic connectors, 161–162

industry applications of, 160

multimode fiber, 160

properties of, 158–159

single-mode fiber, 159

summary of, 169

purpose of, 138–140

summary of, 168

wireless media, 164–167

properties of, 164–165

summary of, 169–170

types of, 165–166

wireless LANs (WLANs), 166–167

physical ports. See ports

physical security, 545–546

physical topologies, 10, 209–211, 659

physical topology diagrams, 659

ping command

default gateway testing with, 450–451

definition of, 659

device connectivity verification with, 78

IOS command syntax, 57

IPv6 verification with, 429

lab exercises for, 455

loopback interface testing with, 356, 450

network baseline assessment with, 593–596

overview of, 449–452

ping sweeps, 547, 659

remote host testing with, 451–452

small business network verification with, 586–590

summary of, 454–455

PNG (Portable Network Graphics), 509

PoE (Power over Ethernet), 659

Point-to-Point Protocol (PPP), 225

point-to-point topologies, 211, 213

policy vulnerabilities, 544

pools, DHCP (Dynamic Host Configuration Protocol), 527

POP (Post Office Protocol), 479, 520, 659

POP3 (Post Office Protocol), 101, 510, 659

Portable Network Graphics (PNG), 509

ports, 9

Cisco IOS, 73–74

definition of, 659

port numbers

definition of, 465, 659

destination, 650

groups of, 478

multiple separation communications with, 476

netstat command, 479–480

socket pairs, 477–478

table of, 510–511

well-known, 479

redirection, 549

registry, 479

scans of, 548, 659

selection of, 573

positional notation

binary, 178–180, 182–186

decimal, 178–179

definition of, 178

POST (power-on self-test), 659

Post Office Protocol (POP3), 101, 479, 510, 520, 659

POST requests, 517

Power over Ethernet (PoE), 659

powerline networking, 31–32, 659

power-on self-test (POST), 659

PPP (Point-to-Point Protocol), 225

Preamble field (Ethernet frames), 238

preferred format, IPv6, 402–406, 659

prefixes, 345, 659

IPv4, 344–345

IPv6, 406–407

presentation layer, 534

definition of, 113

functions of, 508–510

private cloud, 30, 659

private IPv4 addresses, 353–354, 374–377, 659

privileged EXEC mode, 53, 64, 659

protocol analyzers, 660

protocol data units (PDUs), 118–120, 132, 660

Protocol field (IPv4 packets), 276

protocol suites, 97–107. See also TCP/IP (Transmission Control Protocol/Internet Protocol) model

definition of, 660

evolution of, 98–99

overview of, 97–98

protocols. See also specific protocols

definition of, 87–88, 660

functions of, 95–96

interaction between, 96

requirements of, 88–89

types of, 94–95

proxy servers, 660

PSH flag, 486

public cloud, 30, 660

public IPv4 addresses, 353–354, 374–377, 660

PUT requests, 517

PuTTY, 50, 68–70

Q

qBittorrent, 514

QoS (quality of service), 25–26, 582, 660

quality-of-service (QoS), 660

queries, internet, 655

queuing, 660

QuickTime Video (MOV), 509

R

RA (Router Advertisement) messages, 310, 417–418, 446–448, 661

radio frequency interference (RFI), 147, 660

RADIUS (Remote Authentication Dial-in User Service), 495

RAM (random-access memory), 67, 660

random-access memory (RAM), 660

randomly generated interface IDs, 424–425

read-only memory (ROM), 243, 660

real-time traffic, 660

Real-Time Transport Control Protocol (RTCP), 582

Real-Time Transport Protocol (RTP), 582

reconnaissance attacks, 547–548, 660

Redirect message, 310

redundancy, 576–577, 660

reference models. See OSI (Open System Interconnection) model; TCP/IP (Transmission Control Protocol/Internet Protocol) model

Regional Internet Registries (RIRs), 358–359

regional Internet registry (RIR), 661

Regional Latin-American and Caribbean IP Address Registry (LACNIC), 359

reliability, 38

IP (Internet Protocol), 273–274

network, 23–27

of protocols, 96

TCP (Transmission Control Protocol), 486–490, 500–501

UDP (User Datagram Protocol), 494

reload command, 68

Remote Authentication Dial-in User Service (RADIUS), 495

remote communications, ARP (Address Resolution Protocol) in, 305–306

remote hosts

definition of, 282

pinging, 451–452

remote networks, 661

repeaters, 661

replies (ARP), 305

REPLY messages, 529

Representational State Transfer (REST), 102

representations, network, 8–10, 37

requests

ARP (Address Resolution Protocol), 304

TCP (Transmission Control Protocol), 481–482

UDP (User Datagram Protocol), 495–497

requests for comments (RFCs), 209, 661

Réseaux IP Européens Network Coordination Centre (RIPE NCC), 359

Reserved field (TCP headers), 472

resolution, 613

response timeout, 661

responses

TCP (Transmission Control Protocol), 482–483

timeout, 92

UDP (User Datagram Protocol), 497–498

REST (Representational State Transfer), 102

RFCs (requests for comments), 209, 661

RFI (radio frequency interference), 147, 660

ring topology, 214, 661

RIPE NCC (Réseaux IP Européens Network Coordination Centre), 359

RIR (regional Internet registry), 661

RIRs (Regional Internet Registries), 358–359

RJ-11 connectors, 661

RJ-45 connectors, 154, 661

rollover cables, 157

ROM (read-only memory), 243, 660

round-trip time (RTT), 661

route entries, 285, 293

route print command, 283–284

Router Advertisement (RA) messages, 310, 417–418, 446–448, 661

router configuration, 336–337

ARP tables, displaying, 306–307

basic configuration example, 321–323

banner warnings, 322

device name, 321

initial router settings, 323

running configuration, saving, 322

secure access, 322

basic configuration steps, 320–321, 335

default gateways, 330–334

configuration, 330–334

summary of, 335–336

troubleshooting, 334

dynamic LLAs (link-local addresses) on, 426–427

host/router communications, 223–225

interfaces, 323–330

basic configuration, 323–324

dual stack addressing, 324–325

summary of, 335

verification commands, 325–330

Router Solicitation (RS) messages, 310, 417–418, 446–448, 661

routers, 661

routing, 285–291. See also router configuration

definition of, 661

dynamic, 288–290

host communication, 281–284

default gateways, 282–283

host forwarding decisions, 281–282

routing tables, 283–284

IPv4 routing tables, 290–291

router packet forwarding decisions, 285–286

routing tables, 286–287, 290–291

static, 287–288

RS (Router Solicitation) messages, 310, 417–418, 446–448, 661

RST flag, 486

RTCP (Real-Time Transport Control Protocol), 582

RTP (Real-Time Transport Protocol), 582

RTT (round-trip time), 661

running configuration, altering, 68

running-config file, 67

runt frames, 238, 661

S

SACK (selective Acknowledgement), 489

SACK (selective acknowledgment), 662

satellite internet access, 19, 661

SC (subscriber connector) connectors, 161

scalability, small network, 24–25, 583–586, 624

definition of, 661–662

employee network utilization, 584–586

protocol analysis, 583–584

small network growth, 583

SDSL (symmetric DSL), 20

Secure FTP (SFTP), 101, 581, 663

Secure Shell (SSH), 50, 479, 561–562, 580, 662

SecureCRT, 50

security, 33–35

attack mitigation, 552–558

AAA (authentication, authorization, and accounting), 555

backups, 553–554

defense-in-depth approach, 553

endpoint security, 558

firewalls, 555–557

updates and patches, 554

attacks, 546–552

access, 548–549

attack mitigation, 565

malware, 546–547

reconnaissance, 547–548

summary of, 565

design for, 26–27

device, 558–564

Cisco AutoSecure, 558–559

passwords, 559–561

SSH (Secure Shell), 561–562

summary of, 566

unused services, disabling, 563–564

mitigation techniques, 34–35

physical, 545–546

summary of, 39

threats, 33–34

summary of, 565

types of, 542–543

vulnerabilities, 543–544

security passwords min-length command, 560

segmentation, network, 359–362

broadcast domains and, 359–362

definition of, 662

reasons for, 362

summary of, 391

segments, 116–117, 463, 468

ACK (Acknowledgement), 472, 484–485, 486, 488

definition of, 662

MSS (maximum segment size), 491–492

selective Acknowledgement (SACK), 489

selective acknowledgment (SACK), 662

SEQ (sequence) number, 488

Sequence Number field (TCP headers), 472

sequence numbers, 662

sequencing, 96, 118–119

Server Message Block (SMB), 531–533, 662, 663

servers

common software for, 4–5

definition of, 4

TCP (Transmission Control Protocol)

connection establishment, 483–484

server processes, 480–483

session termination, 484–485

three-way handshake, 485–486

types of, 580–581

UDP (User Datagram Protocol), 495

service password-encryption command, 64, 560

services

application layer, 579

disabling, 563–564

file sharing, 530–533

FTP (File Transfer Protocol), 530

SMB (Server Message Block), 531–533

summary of, 535–536

IP addressing, 521–530

DHCP (Dynamic Host Configuration Protocol), 527–529

DNS (Domain Name System), 522–525

nslookup command, 526–527

summary of, 535

session layer, 534

definition of, 113

functions of, 508–510

sessions, 662

SFP (small form-factor pluggable) devices, 161

SFTP (Secure FTP), 101, 581, 663

sharing services. See file sharing services

shell, 47

shells, 662

shielded twisted pair (STP) cable, 150–151, 662

show arp command, 603, 606

show cdp neighbors command, 609–610

show control-plane host open-ports command, 563

show interfaces command, 328, 335, 603, 604–605

show ip arp command, 306–307

show ip interface brief command, 325–326, 335, 610–611, 618

show ip interface command, 329, 335, 603, 605–606, 618

show ip ports all command, 563

show ip route command, 290–291, 293, 327, 335, 603, 606–607, 620

show ipv6 interface brief command, 325–327, 335, 427–428

show ipv6 interface command, 330, 335

show ipv6 route command, 327–328, 335, 428–429

show protocols command, 603, 607

show running-config command, 65, 67–68, 70, 333, 603–604

show startup-config command, 70

show version command, 603, 608, 611

signal attenuation, 147

signaling, 143–144

Simple Mail Transfer Protocol (SMTP), 101, 479, 510, 519–520, 581, 662, 663

simplex LC (Lucent Connector) connectors, 162

single-mode fiber (SMF), 159, 662

size

of messages, 91–92

of networks, 11–12

of windows, 472, 490–491, 667

SLAAC (stateless address autoconfiguration), 101

definition of, 662, 663

EUI-64 process, 422–424

randomly generated interface IDs, 424–425

stateful DHCPv6, 420–421

stateless DHCPv6, 419–420

slash notation, 662

sliding window protocol, 491

small business network management

applications

common applications, 578–579

summary of, 624

voice/video applications, 582

device selection, 573–574, 624

expandability, 573

host and IOS commands for, 596–611

arp, 601–602

ifconfig, 596–601

IP configuration on Linux hosts, 599–600

IP configuration on MacOS hosts, 596–601

IP configuration on Windows hosts, 596–598

ipconfig, 596–598

show arp, 603, 606

show cdp neighbors, 609–610

show interfaces, 603, 604–605

show ip interface, 603, 605–606

show ip interface brief, 610–611

show ip route, 603, 606–607

show protocols, 603, 607

show running-config, 603–604

show version, 603, 608, 611

summary of, 625–626

internet access technologies for, 19–20

IP addressing, 574–576

protocols, 579–581

protocol analysis, 583–584

summary of, 624

redundancy, 576–577, 660

scalability, 624

scaling, 583–586

definition of, 661–662

employee network utilization, 584–586

protocol analysis, 583–584

small network growth, 583

topologies, 572–573

traffic management, 577–578

troubleshooting methodologies, 611–616

basic approach, 612–613

debug command, 613–615, 616

resolution versus escalation in, 613

summary of, 626

terminal monitor command, 615–616

troubleshooting scenarios, 616–623

default gateway issues, 619–620

duplex operation, 617

IP addressing on end devices, 619

IP addressing on IOS devices, 618

mismatch issues, 617

summary of, 626–627

verifying connectivity of, 586–596

network baselines, 593–596

ping command, 586–590

summary of, 625

traceroute command, 590–594

tracert command, 590–593

small office and home office (SOHO) networks, 12, 17–19, 662

smart homes, 31, 662

SMB (Server Message Block), 531–533, 662, 663

SMF (single-mode fiber), 159, 662

SMTP (Simple Mail Transfer Protocol), 479, 510, 519–520, 581, 662

SNMP (Simple Network Management Protocol), 663

socket pairs, 477–478, 663

sockets, 663

SOHO (small office and home office) networks, 12, 17–19, 662

SOLICIT messages, 529

Solicitation messages. See RS (Router Solicitation) messages

solicited-node IPv6 multicast addresses, 432, 663

Source IPv4 Address field, 276

source IPv4 addresses, 122, 123, 125, 299, 663

Source IPv6 Address field, 280

Source MAC Address field, 238

source MAC addresses, 124, 126, 243, 299, 301, 305

Source Port field

TCP headers, 472

UDP headers, 474

sources, 87

Spanning Tree Protocol (STP), 247

speed settings, 257–259, 262

SPI (stateful packet inspection), 557, 663

spoofing, 663

spoofing (ARP), 307–309

spyware, 33

SSH (Secure Shell), 50, 479, 561–562, 580, 662

ST (straight-tip) connectors, 161

standards, 108–111

communications, 111

data link layer, 209

electronic, 111

internet, 109

open, 108–109

physical layer, 141

UTP (unshielded twisted pair) cable, 153–156

star topology, 213–214, 663

Start Frame Delimiter field (Ethernet frames), 238

startup-config file, 67

stateful DHCPv6, 420–421, 663

stateful packet inspection (SPI), 557, 663

stateful protocols, 471. See also TCP (Transmission Control Protocol)

stateless address autoconfiguration. See SLAAC (stateless address autoconfiguration)

stateless DHCPv6, 418–420, 663

stateless protocols, 468

static addressing, 527

static configuration

GUAs (global unicast addresses), 413–416

LLAs (link-local addresses), 413–416

static route propagation, 663

static routing, 287–288

store-and-forward switching, 254–255, 664

STP (shielded twisted pair), 150–151, 662

STP (Spanning Tree Protocol), 247

straight-through UTP cables, 157

straight-tip (ST) connectors, 161

strong passwords, 560

structured design, IPv4, 387–389, 392

device address assignment, 389

IPv4 network address planning, 388

with Packet Tracer, 389, 392–393

subconfiguration mode, 53–54

sublayers, IEEE 802 LAN/MAN, 206–207

submarine cable networks, 160

subnet IDs, 410, 432–433, 664

subnetting, 364–381

definition of, 664

IPv4

/8 networks, 372–373, 391

/16 networks, 367–370, 391

corporate example of, 378–380

DMZ (demilitarized zone), 377

efficiency of, 377–380

maximizing subnets, 377–378

on an octet boundary, 364–366

within an octet boundary, 366–367

with Packet Tracer, 367, 381

private versus public address space, 374–377

summary of, 391–392

unused host IPv4 addresses, minimizing, 377–378

VLSM (variable-length subnet masking), 381–387

IPv6, 432–435

example of, 433–434

with Packet Tracer, 438

router configuration, 435

subnet allocation, 433–434

subnet IDs, 432–433

summary of, 438

subnet IDs, 410, 432–433

subnet masks, 72, 343–344

VLSM (variable-length subnet masking), 381–387

address conservation, 381–383

network address assignments in, 386–387

overview of, 381

subnetting schemes in, 383–385

summary of, 392

subscriber connector (SC) connectors, 161

SVI (switch virtual interface), 664

SVIs (switch virtual interfaces), 74

swarms, 514

switch fabric, 664

switch virtual interfaces (SVIs), 74

Switch(config)# prompt, 53–54

switched virtual interface (SVI), 664

switches

asymmetric switching, 646

Cisco IOS. See Cisco IOS

default gateway configuration on, 332–334

definition of, 664

Ethernet

Auto-MDIX, 259–260

cut-through switching, 255–256, 649

duplex settings, 257–259

fast-forward switching, 256, 652

fragment-free switching, 256, 652–653

memory buffering on, 257

speed settings, 257–259, 262

store-and-forward switching, 254–255, 664

frame filtering, 252–253

frame forwarding methods on, 254–255, 262

learning and forwarding, 248–249

MAC addressing for. See MAC (media access control) addresses

overview of, 248–249

switch virtual interfaces, 77–78

symmetric DSL (SDSL), 20

SYN flag, 486

Syntax Checker

Cisco IOS device configuration with, 66

Cisco IOS navigation with, 55–56

default gateway configuration with, 334

nslookup command, 527

router configuration with, 323

syslog, 664

system speakers, 664

T

T568A/T68B standards, 157–158

tables

ARP (Address Resolution Protocol)

displaying, 306–307

removing entries from, 306–307

binary positional value, 182–186

CAM (content addressable memory), 649

MAC (media access control) address, 248–254

on connected switches, 252

definition of, 656

frame filtering, 252–253

switch fundamentals, 248–249

switch learning and forwarding, 248–249

viewing, 254

routing, 283–284, 286–287, 290–291

TCP (Transmission Control Protocol), 102

applications using, 472–473

congestion avoidance, 493

connection establishment, 483–484

data loss and retransmission, 486–487

definition of, 665

features of, 470–471

flow control, 471, 490–494

headers, 471–472

MSS (maximum segment size), 491–492

packet delivery, 486–487

reliability of, 467–468, 486–490, 500–501

server processes, 480–483

session termination, 484–485

summary of, 499

three-way handshake, 485–486

UDP (User Datagram Protocol) compared to, 469–470

window size, 490–491

TCP/IP (Transmission Control Protocol/Internet Protocol) model

application layer

client-server model, 511–512

definition of, 508

email protocols, 518–521

file sharing services, 530–533

IP addressing services, 521–530

overview of, 101–102

peer-to-peer applications, 513–515

peer-to-peer networks, 512–513

protocols, 508–511

purpose of, 508

summary of, 534

web protocols, 515–518

benefits of using, 112

communication process in, 103–107

definition of, 98, 664

internet layer, 102–103

network access layer, 103

network layer. See also IP (Internet Protocol) addresses

basic operations of, 268–269

characteristics of, 268–274, 292

hops, 269

host communication, 281–284

routing, 285–291

OSI model compared to, 115–116

overview of, 114

Packet Tracer simulation, 116

physical layer. See also copper cabling; fiber-optic cabling

characteristics of, 141–146, 168

fiber-optic cabling, 158–164

purpose of, 138–140

summary of, 168

wireless media, 164–167, 169–170

presentation layer, 508–510

session layer, 508–510

summary of, 131

transport layer, 102

technological vulnerabilities, 543

Telecommunications Industry Association (TIA), 111, 664

Telecommunications Industry Association/Electronic Industries Association (TIA/EIA), 141

Telnet, 50, 479, 580, 664

Tera Term, 50, 60

terabits per second, 145

terminal emulation programs, 50–52, 664

terminal monitor command, 615–616

test-net addresses, 665

text files, capturing configuration to, 68–71

TFTP (Trivial File Transfer Protocol), 101, 479, 511, 665

threat actors, 33, 542

threats, 33–34, 542–543, 565

three-way handshake, 665

three-way handshake (TCP), 485–486

throughput, 146, 665

TIA (Telecommunications Industry Association), 111, 141, 664

Time Exceeded messages, 446

timeout, response, 92

Time-to-Live (TTL) field, 275, 446, 453, 665

timing messages, 92–93

Token Ring LAN technologies, 214, 217

top-level domains, 525

topologies

data link layer, 209–220

access control methods, 216–217

contention-based access, 216–220

controlled access, 217

data link frame, 229

full-duplex communication, 215–216, 653

half-duplex communication, 215, 653

LAN (local area network), 213–214

physical/logical, 209–211

summary of, 228

WAN (wide area network), 211–213

definition of, 665

small business networks, 572–573. See also small business network management

topology diagrams, 8–11

definition of, 10

logical, 10–11

network symbols for, 8–10

physical, 10

ToS (Type of Service) field, 275

traceroute command

definition of, 665

IOS command syntax, 57

small business network verification with, 590–594

summary of, 454–455

testing network connectivity with, 452–453, 455

tracert command, 590–593

Traffic Class field (IPv6 packets), 280

traffic management, 577–578

traffice prioritization, 665

translation, 400–401

Transmission Control Protocol. See TCP (Transmission Control Protocol)

transport input command, 320, 562

transport input ssh command, 563

transport layer

definition of, 113, 114, 462

overview of, 102

port numbers

definition of, 465

groups of, 478

multiple separation communications with, 476

netstat command, 479–480

socket pairs, 477–478

well-known, 479

protocols, 467

responsibilities of, 463–466

role of, 462

segments in, 463, 468

TCP (Transmission Control Protocol)

applications using, 472–473

congestion avoidance, 493

connection establishment, 483–484

data loss and retransmission, 489

features of, 470–471

flow control, 471, 490–494

headers, 471–472

MSS (maximum segment size), 491–492

packet delivery, 486–487

reliability of, 467–468, 486–490, 500–501

server processes, 480–483

session termination, 484–485

summary of, 499

three-way handshake, 485–486

UDP (User Datagram Protocol) compared to, 469–471

window size, 490–491

UDP (User Datagram Protocol)

applications using, 475–476

client processes, 495–498

datagram reassembly, 494

features of, 473–474

headers, 474

overview of, 473

reliability of, 468–470, 494

server processes, 495

summary of, 499, 501

TCP (Transmission Control Protocol) compared to, 469–470

Trivial File Transfer Protocol (TFTP), 101, 479, 511, 665

Trojan horses, 33, 547, 665

troubleshooting

default gateways, 334

definition of, 665

small business networks, 611–623

basic approach, 612–613

debug command, 613–615, 616

default gateway issues, 619–620

DNS issues, 621–623

duplex operation, 617

IP addressing on end devices, 619

IP addressing on IOS devices, 618

mismatch issues, 617

resolution versus escalation in, 613

summary of, 626–627

terminal monitor command, 615–616

trust exploitation, 548–549

TTL (Time-to-Live) field, 275, 446, 453, 665

tunneling, 400, 665

twisted-pair. See STP (shielded twisted pair); UTP (unshielded twisted pair)

Type of Service (ToS) field (IPv4 packets), 275

Type/Length field (Ethernet frames), 239

U

UDP (User Datagram Protocol)

applications using, 475–476

client processes, 495–498

datagram reassembly, 494

definition of, 102, 666

features of, 473–474

headers, 474

overview of, 473

reliability of, 468–470, 494

server processes, 495

summary of, 499, 501

TCP (Transmission Control Protocol) compared to, 469–470

undebug command, 614

unicast, 93

IPv4, 349–350, 390

IPv6, 406, 407–408, 436–437

MAC addresses, 244–245

unknown, 250

unicast transmission

definition of, 665

unknown, 666

uniform resource locators (URLs), 515, 557

unique local addresses, 408, 665–666

unknown unicast, 250, 666

unshielded twisted pair. See UTP (unshielded twisted pair) cable

unspecified addresses, 666

unused host IPv4 addresses, minimizing, 377–378

unused services, disabling, 563–564

updates, security, 554

uploads, 512

URG flag, 486

Urgent field (TCP headers), 472

URLs (uniform resource locators), 515, 557

User Datagram Protocol. See UDP (User Datagram Protocol)

user executive mode, 53, 666

user passwords. See passwords

username command, 562

uTorrent, 514

UTP (unshielded twisted pair), 152–158

connectors, 153–156

crossover, 157

definition of, 148–150, 666

properties of, 152–153

standards, 153–156

straight-through, 157

summary of, 169

T568A/T68B standards, 157–158

V

variable-length subnet masking. See VLSM (variable-length subnet masking)

verification. See also configuration

of device connectivity, 78, 80

of IP (Internet Protocol) configuration, 77

of IPv6 addressing, 427–430

of router interfaces, 325–330

show interfaces command, 328

show ip interface brief command, 326

show ip interface command, 329

show ip route command, 327

show ipv6 interface brief command, 326–327

show ipv6 interface command, 330

show ipv6 route command, 327–328

of small business network connectivity, 586–596

network baselines, 593–596

ping command, 586–590

summary of, 624

traceroute command, 590–594

tracert command, 590–593

Version field

IPv4 packets, 275

IPv6 packets, 280

video, file formats for, 509

video applications, 29, 582

virtual circuits, 666

virtual classrooms, 666

virtual private networks (VPNs), 35

virtual terminal (vty), 64

virtualization, 666

viruses, 33, 546, 666

VLANs (virtual local area networks), 666

VLSM (variable-length subnet masking), 381–387

address conservation, 381–383, 385

definition of, 666

network address assignments in, 386–387

overview of, 381

summary of, 392

voice applications, 582

voice over IP (VoIP), 666–667

VoIP (voice over IP), 469, 582, 666–667

volatile memory, 667

VPNs (virtual private networks), 35

vty (virtual terminal), 64, 666

vulnerabilities, 543–544

W

WANs (wide area networks), 14–15

definition of, 14–15, 667

topologies, 211–213

hub-and-spoke, 211–212

mesh, 212

point-to-point, 211, 213

WAN frames, 225–226

WAPs (wireless access points), 138, 166, 667

weak passwords, 559

web browsers, 515–517

web pages, opening, 515–517