NAME
domainname - set or display name of the current domain

SYNOPSIS
domainname [ name-of-domain ]

DESCRIPTION
Without an argument, domainname displays the name of the current
domain, which typically encompasses a group of hosts under the same
administration.

Only the super-user can set the name of the domain by giving
domainname an argument; this is usually done in the startup script
/etc/rc.

SEE ALSO
named(8), sendmail(8)