Use Models to Understand IP Networking

Client

A network device or software that requests services, information, or resources from a server. [Objective 1.1: Explain the role and function of network components]

Server

A network device or software that provides services, information, or resources to fulfill client requests. [Objective 1.1: Explain the role and function of network components]

OSI Reference Model

A seven-layer conceptual model created by the ISO to describe network communications, often used as a reference point when discussing modern protocols. [Objective 1.1: Explain the role and function of network components]

TCP/IP Protocol Stack

The standard suite of protocols actively used for communications on the internet and modern corporate networks. [Objective 1.1: Explain the role and function of network components]

Application Layer

The top layer of the TCP/IP stack that provides network services directly to user applications, encompassing protocols like HTTP, HTTPS, and DNS. [Objective 1.1: Explain the role and function of network components]

HTTP (Hypertext Transfer Protocol)

An application layer protocol that delivers web pages and relies on TCP at the transport layer for reliable delivery. [Objective 1.1: Explain the role and function of network components]

DNS (Domain Name System)

An application layer service that resolves human-readable hostnames to IP addresses, typically utilizing UDP at the transport layer for fast queries. [Objective 4.4: Explain the role of DHCP and DNS within the network]

Transport Layer (Layer 4)

The layer in the protocol stack responsible for establishing end-to-end connections and managing data delivery between applications, utilizing protocols like TCP and UDP. [Objective 1.5: Compare TCP to UDP]

TCP (Transmission Control Protocol)

A connection-oriented transport layer protocol that provides reliable delivery of data, commonly used by web services like HTTP and HTTPS. [Objective 1.5: Compare TCP to UDP]

UDP (User Datagram Protocol)

A connectionless, best-effort transport layer protocol that is faster than TCP and commonly used by services like DNS. [Objective 1.5: Compare TCP to UDP]

ipconfig /flushdns

A Windows command prompt utility used to clear the local DNS resolver cache, forcing the computer to perform a fresh DNS lookup for the next request. [Objective 4.4: Explain the role of DHCP and DNS within the network]

ipconfig /displaydns

A Windows command prompt utility used to view the local DNS resolver cache containing recent hostname-to-IP address mappings. [Objective 4.4: Explain the role of DHCP and DNS within the network]

Network Layer (Layer 3)

The layer responsible for logical addressing and routing, using IP addresses to forward data across different networks. [Objective 1.6: Configure and verify IPv4 addressing and subnetting]

ipconfig

A Windows command prompt utility used to display the current TCP/IP network configuration, including the IP address, subnet mask, and default gateway. [Objective 1.6: Configure and verify IPv4 addressing and subnetting]

Default Gateway

The IP address of the local router interface that a host uses to send traffic to devices located on remote networks. [Objective 1.6: Configure and verify IPv4 addressing and subnetting]

Data Link Layer (Layer 2)

The layer responsible for local node-to-node delivery within the same network segment, utilizing MAC addresses to forward frames. [Objective 1.1: Explain the role and function of network components]

MAC Address

A 48-bit (12 hexadecimal character) physical address burned into a network interface card (NIC) by the manufacturer, used for local Layer 2 forwarding. [Objective 1.1: Explain the role and function of network components]

ipconfig /all (or ipconfig -all)

A Windows command prompt utility that displays exhaustive network adapter details, including the physical (MAC) address, DNS servers, and DHCP lease information. [Objective 1.6: Configure and verify IPv4 addressing and subnetting]

ARP (Address Resolution Protocol)

A protocol used to dynamically discover and map a known Layer 3 IP address to an unknown Layer 2 MAC address on the local network segment. [Objective 1.1: Explain the role and function of network components]

arp -a

A Windows command prompt utility used to display the local ARP cache, showing dynamically and statically learned IP-to-MAC address mappings. [Objective 1.1: Explain the role and function of network components]

Physical Layer (Layer 1)

The layer responsible for the transmission of raw bit streams over physical network media, such as copper cables, fiber optics, or wireless airwaves. [Objective 1.3: Compare physical interface and cabling types]

Layer 2 Switch

A network device that forwards data frames on the local network segment by making forwarding decisions based entirely on destination MAC addresses. [Objective 1.1: Explain the role and function of network components]

Router

A network device that forwards data packets between different IP networks by making routing decisions based on destination IP addresses. [Objective 1.1: Explain the role and function of network components]

Protocol Data Unit (PDU) Names

The naming convention for data at various layers: Segment at Layer 4, Packet at Layer 3, Frame at Layer 2, and Bits at Layer 1. [Objective 1.1: Explain the role and function of network components]

Encapsulation

The process of appending layer-specific headers (such as TCP, IP, and MAC) to data as it moves down the protocol stack for network transmission. [Objective 1.1: Explain the role and function of network components]

De-encapsulation

The process of reading and stripping away layer-specific headers as received data moves back up the protocol stack to the application. [Objective 1.1: Explain the role and function of network components]

Wireshark

A network protocol analyzer and packet capture utility used to inspect detailed header information at every layer of the network protocol stack. [Objective 1.1: Explain the role and function of network components]