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Silver1110

Networking

How DNS Resolution Works

Trace a hostname from your browser through resolvers to an IP address.

5 min read · intro · beat Silver to climb

What DNS Solves

The Domain Name System translates human friendly names like example dot com into IP addresses that routers understand.

The Resolution Path

When a name is not cached, a recursive resolver walks a hierarchy:

  • The root servers point to the right top level domain servers.
  • The TLD servers for com point to the domain's authoritative servers.
  • The authoritative server returns the final record.

The resolver then hands the answer back to your application and caches it.

Record Types and TTL

  • An A record maps a name to an IPv4 address.
  • An AAAA record maps to an IPv6 address.
  • A CNAME aliases one name to another.
  • The TTL sets how long a record may be cached, trading freshness against load.

Caching at the browser, operating system, and resolver layers means most lookups never reach the authoritative server.

Key idea

DNS resolves a name by walking root, TLD, and authoritative servers, with TTL controlled caching cutting most of that work.

Check yourself

Answer to earn rating on the learn ladder.

1. Which server returns the final authoritative answer for a domain?

2. What does a DNS record TTL control?