ServerName
ServerName fully-qualified-domain-name Server config, virtual host
The ServerName directive sets the hostname of the
server; this is used when creating redirection URLs. If it is not
specified, then the server attempts to deduce it from its own IP
address; however, this may not work reliably or may not return the
preferred hostname. For example:
ServerName www.example.com
could be used if the canonical (main) name of the actual machine were
simple.example.com, but you would like visitors
to see www.example.com.