I was facing today the situation that a Dynamics AX Client in a trusted ActiveDirectory Domain was not able to connect to the Dynamics AX AOS in the other Domain.
When launching the Dynamics AX Client, the following error message showed up:
We were able to ping the IP address of the AOS and by using telnet to the port of the AOS we were also sure no one was blocking the TCP port.
The cause connection issue was the failing name resolution. By adding the NetBIOS computer name to the lmhosts files the connection could be established.
In a scenario where you have two trusted ActiveDirectory Domains (in different ActiveDirectory Forrests), and the Workstations and Users are placed in one ActiveDirectory Domain while the AOS is placed in the other ActiveDirectory Domain, it is very important that both the DNS as well as the WINS name resolution work correctly - either by setting up DNS / WINS Servers or by modifiying the hosts / lmhosts file!