DNS Caching

Problem

Millions of users repeatedly ask: What's the IP of example.com? Querying authoritative DNS infrastructure for every request would be wasteful and slow.

Solution — DNS Cache

Resolvers temporarily remember answers.

example.com → 203.0.113.10
TTL: 300s

Future requests can use the cached result until it expires.

Core idea: DNS caching reduces lookup latency and authoritative DNS load.