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''.