DNS & domain names

Its job in the system

DNS separates a memorable name from the numerical addresses used by the network. A browser generally asks a resolver to obtain the relevant records. DNS is a distributed database with delegated authority, so no single server contains every answer and no ordinary lookup must consult every level from the beginning.

How it works

If a usable answer is already cached, a resolver can return it without repeating the full discovery process. Otherwise, it can follow referrals through the naming hierarchy until it reaches an authoritative server for the relevant name. Responses have lifetimes that govern ordinary caching. A name can have more than one address or point through an alias.

The result helps the application choose where to connect; DNS does not carry the subsequent page body. It is therefore possible for an address lookup to succeed while a website connection fails, or for a previously known address to work while a new lookup encounters trouble. Naming, routing, and application service are separate dependencies.

What it connects to

DNS queries themselves travel over a network. A resolver may be supplied by the access provider or selected through device or application settings. Domain registries, registrars, authoritative operators, and resolvers have different roles. ICANN coordinates parts of the global identifier system; it does not operate every DNS server or control all internet content.

Different places, different designs

Answers can vary by location, service design, address family, and time. Encrypted DNS transports can protect the query connection to a resolver, while DNSSEC addresses authenticity of DNS data; these are different properties. The basic journey does not attempt to simulate either mechanism or every resolver policy.