Java APIs

Hi,
Our application is deployed in different servers.
When I try to access a specific domain in Active Directory, I'm getting following exceptions.

In one server, I'm getting - java.net.ConnectException: A remote host refused an attempted connect operation.

and in the other server - java.net.SocketException: Connection timed out:could be due to invalid address

Few times I could retrieve details. But few times I'm getting above exceptions.
I couldn't figure out what is the issue?

Any suggestions on this issue?

Thanks in Advance..