Networking Basics

Two basic building blocks you keep running into with networking, compared simply.

Last updated: September 1, 2026

Transmission

TCP vs UDP

Two basic ways data gets sent across a network.

TCP

Connection orientedEstablishes a fixed connection first, before data flows

ReliableChecks that every data packet really arrives, and resends it if needed

Slightly slowerThe checks create a bit of extra overhead

Typical useWebsites, email, file transfer, SSH

UDP

ConnectionlessJust sends data packets off, without setting up a connection first

No guaranteeLost packets aren't automatically resent

FasterLess overhead, so less delay

Typical useVideo streaming, online games, DNS queries

Worth a look

Connection setup compared

TCP deliberately sets up a connection in three steps, UDP just sends data straight away.

Client

Server

TCP: SYN, SYN-ACK, ACK, only then does the actual data flow.

Client

UDP: data is sent directly, with no confirmation or setup.

Addressing

IPv4 vs IPv6

Two versions for uniquely addressing devices on the internet.

IPv4

FormatFour number blocks, like 192.168.1.1

Address spaceAround 4.3 billion possible addresses

AdoptionStill the standard in everyday use

LimitationAddresses are slowly running out worldwide

IPv6

FormatEight number blocks in hexadecimal, like 2001:0db8::1

Address spacePractically inexhaustible number of addresses

AdoptionSteadily growing, but slower than originally planned

AdvantageSolves the problem of running out of addresses long term

At a glance

On my own server, I run into both of these topics daily, TCP for example when loading this website over HTTPS, UDP for example with DNS queries in the background.