Chapter 2: Networks and the Internet – VOCAB Flashcards

A comprehensive set of vocabulary flashcards covering OSI model, network devices, addressing, cabling, protocols, Internet concepts, and common utilities as presented in Chapter 2.

OSI model

Seven-layer model used to organize network functions; helps isolate problems; each layer supports the one above and performs a specific function.

Application layer (OSI)

Layer 7; interfaces directly to applications and provides common services (e.g., protocols such as POP, SMTP, DNS, FTP).

Presentation layer (OSI)

Layer 6; handles data representation differences to simplify communication between systems.

Session layer (OSI)

Layer 5; manages dialogue and control between end-user application processes.

Transport layer (OSI)

Layer 4; provides end-to-end data transport; protocols include TCP and UDP.

Network layer (OSI)

Layer 3; routes information across the network; uses protocols such as IP and ARP.

Data Link layer (OSI)

Layer 2; contains MAC and LLC sublayers; describes the organization of data bits and frames; uses MAC addresses.

Physical layer (OSI)

Layer 1; defines physical properties of media, electrical signals, and the hardware (NIC, cables).

MAC address

Physical hardware address burned into the NIC; 48-bit hex; used for identification on the local network (layer 2).

NIC

Network Interface Card; device that connects a host to the network and operates at the physical layer.

RJ-45

Ethernet connector used for network cabling; larger than RJ-11 and connects to patch panels.

Hub

Simple, layer-1 device that broadcasts traffic to all ports; no routing or switching.

Switch

Layer-2 device that forwards frames only to the intended destination host; smarter than a hub.

Router

Layer-3 device that routes traffic between networks and controls traffic scope.

Internet

Global network consisting of ISPs and backbone providers connected via points like Network Access Points (NAPs).

IPv4 address

Four-octet 32-bit address used to identify devices; public addresses are routable; private addresses use NAT for Internet access.

Public IP address

Routable on the Internet and typically leased from an ISP.

Private IP address

Not routable on the Internet; used within private networks; NAT translates to a public IP.

NAT (Network Address Translation)

Translates private addresses to a public address to enable Internet access for devices on a private network.

DNS

Domain Name System; translates human-friendly domain names to IP addresses.

URL

Universal Resource Locator; human-friendly web address; DNS resolves it to an IP.

10BASE5

Thick Ethernet (Thicknet); old coaxial cabling standard.

10BASE2

Thin Ethernet (Thinnet); coaxial cabling standard.

10BASE-T

Ethernet over twisted-pair copper cabling.

10BASE-F

Ethernet over fiber-optic cabling.

100BASE-T

Fast Ethernet; 100 Mbps over twisted-pair copper.

1000BASE-T

Gigabit Ethernet; 1 Gbps over twisted-pair copper.

RJ-11

Telephone-style jack used for telephony connections.

Class A IP addresses

First octet 0-126; designed for extremely large networks; largely exhausted.

Class B IP addresses

First octet 128-191; for large corporate networks; largely exhausted.

Class C IP addresses

First octet 192-223; most common; used by many ISPs.

Class D IP addresses

First octet 224-239; multicast addresses.

Class E IP addresses

First octet 240-255; reserved for experimental use.

Subnet

A portion of a network that shares the same subnet address.

Subnet mask

Defines which portion of an IP address belongs to the subnet.

CIDR

Classless Inter-Domain Routing; describes subnets using IP address notation with a slash (e.g., 192.168.1.0/24).

IPv6

128-bit IP address space; supports options like DHCP for configuration.

Protocol

Rules that govern network and Internet communication; IETF controls these rules.

TCP

Transmission Control Protocol; connection-oriented; ensures reliable delivery.

IP

Internet Protocol; connectionless protocol; works with TCP to deliver data.

UDP

User Datagram Protocol; connectionless transport protocol.

ICMP

Internet Control Message Protocol; used to report problems and errors in network communication.

FTP

File Transfer Protocol; used to transfer files between computers.

HTTP/HTTPS

Hypertext Transfer Protocol; used to retrieve web pages; HTTPS is its secure version.

DNS servers

Servers that resolve domain names to IP addresses.

Port

Logical endpoint for network communications used by protocols; not a physical port.

Firewall

Security device (hardware or software) that filters incoming/outgoing traffic.

Proxy server

Security device that hides internal addresses and can cache content; acts on behalf of clients.

Basic network utilities

Tools such as IPConfig, Ping, Tracert, Netstat, and Nslookup used to diagnose networks.

IPConfig

Utility to display network configuration, including IP address, subnet mask, and default gateway.

Ping

Utility to test reachability and round-trip time to a host.

Tracert

Traceroute utility; shows each hop between source and destination.

Netstat

Displays active connections and listening ports.

Nslookup

DNS lookup tool to query DNS records.

Error message classes

HTTP status-like grouping: 100 informational, 200s success, 300s redirects, 400s client errors, 500s server errors.

Network address point (NAP)

A point where backbone providers connect to exchange traffic.