10.4 Domain Name Service (DNS)
Hosts are referred to by domain name as well as by IP address. DNS is a
client-server system in which name resolvers consult nameservers in order to
associate domain names with IP addresses and other properties of hosts. The
GNU C Library
resolver(3) can also look up IP addresses in files
or consult Network Information Services (NIS).
Some software (e.g., GNOME) expects the system hostname to be resolvable to an
IP address with a canonical fully qualified domain name. This is really
improper because system hostnames and domain names are two very different
things; but there you have it. In order to support that software, it is
necessary to ensure that the system hostname can be resolved. Most often this
is done by putting a line in
/etc/hosts containing some IP address
and the system hostname. If your system has a permanent IP address then use
that; otherwise use the address 127.0.1.1.
To see whether your system hostname can be resolved to an IP address with a
fully qualified domain name, use the hostname --fqdn command.