Networking Fundamentals and the OSI Model

Vocabulary flashcards covering core networking terminology, the OSI model layers, protocols, technologies, and foundational concepts.

Network

Two or more devices connected so they can communicate and share resources.

Protocol

An agreed-upon set of rules devices use to communicate.

OSI Model

Open Systems Interconnection Model — a seven-layer conceptual framework used to understand network communication.

Layer

A logical level of the OSI model responsible for particular networking functions.

Encapsulation

The process of adding networking information as data moves down through the networking layers.

De-encapsulation

Removing networking information as received data moves back up through the layers.

PDU

Protocol Data Unit — the name given to data at a particular networking layer.

Application Data

Information created or used by an application before transport across the network.

Segment

A common term for a TCP PDU at Layer 4.

Datagram

A term commonly associated with UDP data at Layer 4.

Packet

The Layer 3 unit of data.

Frame

The Layer 2 unit of data.

Bit

A binary 1 or 0; the basic unit associated with Layer 1 transmission.

Layer 7 – Application

Provides network services used by applications.

Layer 6 – Presentation

Handles representation, formatting, encryption, encoding, and compression of data.

Layer 5 – Session

Establishes, manages, and ends communication sessions.

Layer 4 – Transport

Provides end-to-end communication between applications.

Layer 3 – Network

Handles logical addressing and routing between networks.

Layer 2 – Data Link

Handles communication across the local network/link.

Layer 1 – Physical

Transmits raw bits using electrical, optical, or radio signals.

Ethernet

A widely used technology for local-area networking (Layers 1–2).

Wi-Fi

Wireless local-area networking technology (Layers 1–2).

NIC

Network Interface Card/Controller — hardware that connects a computer to a network (Primarily Layers 1–2).

MAC Address

An address associated with a network interface for local network communication (Layer 2).

Switch

A device that primarily forwards frames within a LAN using Layer 2 information (Layer 2).

VLAN

Virtual Local Area Network — logically separates Layer 2 networks (Layer 2).

IP Address

A logical address used to identify and communicate with devices across IP networks (Layer 3).

IPv4

Version 4 of the Internet Protocol (Layer 3).

IPv6

Version 6 of the Internet Protocol (Layer 3).

Router

A device that forwards packets between networks (Layer 3).

Routing

Determining where packets should be sent to reach another network (Layer 3).

Subnet

A logical subdivision of an IP network (Layer 3).

Default Gateway

The router a host normally uses to reach destinations outside its local subnet (Layer 3).

TCP

Transmission Control Protocol — provides reliable, connection-oriented transport (Layer 4).

UDP

User Datagram Protocol — provides connectionless transport with less overhead than TCP (Layer 4).

Port

A number used to identify a particular application or service endpoint (Layer 4).

HTTP

Hypertext Transfer Protocol — used for web communication (Application layer).

HTTPS

HTTP protected using TLS (Application-layer protocol using lower-layer security/transport mechanisms).

DNS

Domain Name System — translates names such as google.com into IP addresses and provides other naming records (Application layer).

DHCP

Dynamic Host Configuration Protocol — automatically provides devices with IP configuration information (Application layer).

Firewall

A security system that permits or blocks network traffic according to rules; modern firewalls can inspect multiple layers (Multiple layers).

LAN

Local Area Network — a network covering a limited area such as a home, lab, or building (Concept).

WAN

Wide Area Network — connects networks over larger geographic areas (Concept).

Bandwidth

The capacity of a communication link to carry data (Primarily Layer 1 concept).

Latency

The amount of delay experienced during communication (Network-wide concept).