I have set up an AD Agent on a 2008 R2 member server and added two 2008 R2 DCs through "adacfg dc create". Both DCs have account logon audit logging activated and they were working, showing status of "UP" when running the "adacfg dc list" for about two weeks until just recently. Now the first DC listed shows status of "down" despite no reported changes being made on either the DC or the AD Agent server. The other server still shows "up" and works with the ASA to track IP/user mappings. Both the ADA and DC servers have been restarted with no change. I have removed and re-added both DCs from the AD Agent and the same one refuses to go into an "up" state. I am using the FQDN of the servers and am able to resolve its name successfully from the ADA server. Just to be sure I have verified that account logon auditing is set for success and failure. I have also made sure that the WMI service is running and there is no firewall, Windows or otherwise, interfering. What else should I check for, either in the server configurations or in the ADObserver log?
