If you set machineName="foo.com" in the server side remoting config (to avoid using ip addresses) and probably need to deploy the same config on multiple servers use machineName="$hostName" and remoting will substitute this with the current host dns qualified name. This way you dont have to hardcode any machinenames in config.

Note: this is only available on the server channel config. On the client, as it might be obvious the full server name is required.