DNS obtains your default domain name from your resolv.conf file.
If the resolv.conf file is not available, or does not identify a default domain, and if your enterprise-level name service is either NIS+ or NIS, the Sun implementation of DNS obtains the default domain name from those services.
If resolv.conf is not available or does not provide a domain name and you are not running either NIS+ or NIS, you must either provide a resolv.conf file on each machine that does specify the domain (see "The Resolver"), or set the LOCALDOMAIN
environment variable.