DNS servers and clients

DNS data (hostnames mapped to addresses) is stored on servers, which answer requests from DNS clients in a process called resolution. All servers run client software; the only pure client implementation is the remote server. The SCO implementation of DNS supports five types of configuration:

Primary server

Computer containing data authoritative for one or more zones. See ``Primary servers''.

Secondary server

Backup computer that contains a copy of the primary's files in case of primary failure. See ``Secondary servers''.

Caching-only server

Computer that stores and sometimes serves data for a zone but is not authoritative. See ``Caching-only servers''.

Remote server

Client computer that runs DNS software but uses a remote server to resolve requests. See ``Remote servers''.

Server in slave mode

Server that handles resolution via DNS forwarders only. See ``Slave mode servers''.