And if localhost doesn't work, 127.0.0.1 will, as long as the database is being served on the same server. (As it should be for all DA servers.)
In fact you should never use any other IP#; you should always use either localhost (if it works) or 127.0.0.1, for two reasons...
a) to avoid using your outgoing bandwidth.
b) to avoid connections being slowed down by the speed allowed by the router and external Internet connection.
Jeff