UDP
ExplainedProtocol / format
Also known as: User Datagram Protocol
Fast but unreliable transport protocol, for when speed matters more than completeness.
UDP, explained
Written by EduVerseWhat it is
UDP (User Datagram Protocol) is a transport protocol that simply sends packets, called datagrams, without setting up a connection first. It doesn’t check whether they arrive, doesn’t resend lost ones and doesn’t put them back in order. That keeps it lightweight and fast, and leaves reliability to the application if it needs any.
Why teams use it
For a video call or an online game, a packet that arrives late is useless anyway, so waiting for a resend as TCP does only adds lag. UDP lets the application decide how to handle the gaps. It also suits tiny exchanges like most DNS lookups, where a full connection would be overkill.
An example from work
In a docker-compose.yml you notice one port mapping written as 53:53/udp, while all the others have no suffix. Without it, Docker forwards only TCP, so a DNS server in that container would never receive its queries. The protocol is part of the port, and firewall rules make the same distinction.
Our own explanation, not a quote from the book.
Where it fits
Video streaming, online gaming, DNS lookups
Coverage in the book
Explained and compared with alternatives, so you know where and why it’s used.
