Windows Mobile does not have an ordinary “hosts” file for manually overriding DNS. This has to be performed through registry entries instead. The Hosts File Editor is a small utility that will let you add entries in a more-user friendly way. It will also let you remove entries.
This is perfect for test scenarios where you either don’t have the proper DNS records in place, or if you want to override the DNS resolution, and direct the traffic to a specific IP address.