join a domain from a different network

i have configured the win2k domain controller in the domain A which is in the network address 202.185.111.X

I then configured the winXp proffesional (which is in the network address 202.185.80.X )as a member of the domain A in the by editing the Hosts file, Since i didn’t have Wins on my network.

After logging on in the client system as a member of the domain A and when i tried to acces the domain controller by providing the same username and password as the login.

i received a error” The username you typed is the same as the username you logged in with. That username has already been tried.A domain controller cannot be found to verify that username”