DNS

The system that maps domain names to network addresses.

Motivation

DNS solves the problem of translating human-friendly names into network addresses. People remember names like example.com; computers route traffic using IP addresses.

Where it fits

DNS belongs to computer networks and is essential for web applications, APIs, cloud infrastructure, and service discovery.

Mental model

DNS is a distributed naming system. A resolver asks a hierarchy of DNS servers how to find the address for a domain name.

Common mistakes

Forgetting DNS responses can be cached.
Ignoring TTL when changing infrastructure.
Treating DNS as instant or globally consistent.