1) It is possible that the DNS name being used is resolved as an IPV6 address instead of an IPV4 address. You would have to double check with your network team if that is the case.
If that is the case, then you want to make sure that you are using the IPV6 Port of 8046, which is the default, and also check the value of "Choose listeners" in your TCPIP section of your Global Parameters tab via the GUI. You may want to set it to "All listeners". Keep in mind that you will have to stop/start the XCOM service after making any changes to the Global Parameters.
2)Verify the host name corresponds to the IP address - Does it work if you specify the IP address?
3) Check for a firewall
4) Incorrect port
5) Try flushing the name resolver cache in the local box