Domain Name System (DNS)

Definition

The Domain Name System (DNS) is the distributed system that publishes and resolves names used by Internet services.

How it works

DNS is the internet's directory service. Records live in zones delegated from the root, down through top-level domains, to the nameservers responsible for each domain — and resolvers walk that chain to turn a name like www.example.com into the address of a server or the destination for your email. Every website visit starts with a DNS lookup, usually finished in milliseconds.

Example: A browser uses DNS to find the IP address behind www.example.com before it opens a connection.

Often confused: DNS points the way to your services; it does not host content or redirect browsers on its own.

Related terms

• Authoritative nameserver
• DNS record
• Nameserver
• Recursive resolver
• Zone file

Learn more from Bitfoo

• Learn how DNS works

Sources

• IETF RFC 1034: Domain Names — Concepts and Facilities
• IETF RFC 1035: Domain Names — Implementation and Specification

Last reviewed 2026-07-19.