Can you "telnet <ds-server> 389" ?? That is, is access to the port actually gone?
If so, this isn't an Exchange issue per se – the Exchange problem is just a symptom of a larger problem.
Michael B. Smith
From: exchangelist-bounce@xxxxxxxxxxxxx [mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of Mahadevan Subramanian
Sent: Wednesday, January 02, 2008 11:00 AM
Subject: [ExchangeList] DSAccess Topology Discovery Fails.
Windows 2003 AD With Native Mode
Exchange 2003 SP2 with Native Mode
We have vague issue in DSAccess Topology discovry only in one particular Front End Exchange server which we use it as Mobility Server.Every week the topology discovery will fail with 2110, 2115, 2114, 2095, 2102, 2103...... events. The main error is " Process MAD.EXE (PID=1908). Could not bind to DS server XXXXXXXX Error 5a in Port 389". There is no use in running any tests like netdiag, nltest, policy test during this time because it is not able to communicate with port 389. The only temporary slution which we have is Reboot the Exchange server after which it will work fine for another week.
Did the following things..
Increased Diagnostic Logging for DSAccess and hence got the above mentioned events...
Ran ExBPA and found nothing fishy, except 3GB switch enabled in the Front End Server which is not there in any other FE servers.
Memory usage is normal.
We are planning to take this up with Microsoft but before that just thought of getting any of your suggestions if any one has faced this issue.