Basics of Networking

Layer 7

Application layer. Interacts directly with software applications (web browsers, email clients) using protocols like HTTP and DNS.

Layer 6

Presentation layer. Translates, encrypts, and compresses data so the application layer can understand it.

Layer 5

Session layer. Opens, manages, and closes communication sessions between different devices.

Layer 4

Transport layer. Breaks data into segments and ensures reliable delivery using protocols like TCP and UDP.

Layer 3

Network layer. Handles logical addressing (IP addresses) and routes data packets across different networks.

Layer 2

Data link layer. Manages node-to-node communication and error checking on the same local network using MAC addresses.

Layer 1

Physical layer. Converts data into electrical, optical, or radio signals to transmit raw bits across physical media like cables.

TCP

A reliable, connection-oriented transport protocol that ensures accurate and ordered data delivery. It uses control mechanisms to guarantee data correctness, which makes it slower but dependable. (three way handshake)

UDP

A fast, connectionless transport protocol that sends data without reliability guarantees. It is efficient for applications where speed is more important than accuracy.

Network

A group of connected devices that share data

Node

Any single device attached to a network (computer, phone)

Switch

A box that links devices inside the same local network and moves data between them

Router

A device that connects different networks together and sends data packets across them

Firewall

A security tool that blocks bad or unauthorized traffic

IP Address

A unique number given to a device so that other devices can find it

MAC Address

A permanent, physical hardware address built into a device’s network card

WAN

Wide area network. A large network that links multiple smaller networks over long distances.

Protocol

A shared set of rules that lets other machines talk wtihout errors.

DNS

Domain Name System. A ‘phonebook’ for the internet that turns website names into numerical IP addresses

DHCP

Dynamic Host Configuration Protocol. A protocol that automatically assigns IP addresses and network configuration settings to devices on a network.