Using Netdiag on my Exchange server - Problems with DC

I run a net diag to find out why I am having issues my exchange server, and I get this pieces of info I ma confused and would like to clean up the network or domain so that I do not run into these issues, can someoexplain what these mean...My domian name is when i logon to the domain controler is is looking for CORP as the domain....
DC discovery test. . . . . . . . . : Failed
        [FATAL] Cannot find DC in domain 'CORP'. [ERROR_NO_SUCH_DOMAIN]

DC list test . . . . . . . . . . . : Failed
        'CORP': Cannot find DC to get DC list from [test skipped].

Trust relationship test. . . . . . : Failed
    'CORP': Cannot find DC to get DC list from [test skipped].
    Secure channel for domain 'CORP' is to '\\'.

Kerberos test. . . . . . . . . . . : Skipped
        'CORP': Cannot find DC to get DC list from [test skipped].

LDAP test. . . . . . . . . . . . . : Failed
    Cannot find DC to run LDAP tests on. The error occurred was: The specified domain either does not exist or could not be contacted.

        [WARNING] Cannot find DC in domain 'CORP'. [ERROR_NO_SUCH_DOMAIN]

Bindings test. . . . . . . . . . . : Passed

WAN configuration test . . . . . . : Skipped
    No active remote access connections.

Modem diagnostics test . . . . . . : Passed
Scott JohnstonIT Manager Asked:
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Please Check if you DNS is setup correctly.
Did you change ip or computer name ?
Scott JohnstonIT Manager Author Commented:
No , I did upgrade my domain controler from Win200 to Win2003 about1 year ago.  This problem very flakey.....
Scott JohnstonIT Manager Author Commented:
Today I run the NetDiag and the DC is fine, passed all the tests......However I have a weird event ID 8231  not sure if this is something or not...
Scott JohnstonIT Manager Author Commented:
I found this on another  site:
Error 80040103 - This occurred after adding a new, and demoting an old DC. It seems that the Recipient Update service in the System Manager failed to redirect itself to the new DC and the old DC did not remove itself from DNS in gc._msdcs as a Global Catalog. As a result, Exchange can't connect to the LDAP for the address lists (try to preview them and it will fail) and therefore won't update AD with any subsequent changes to the directory.
Fix:  Re-promote the old DC, goto the Exchange System Manager and manually change the RUS connector to point to the new DC. Then go into the gc._msdcs folder in DNS and manually change all references from the old DC to the new DC.
I like to reboot everything after these steps and after the reboot these errors should no longer appear, you will be able to preview the address lists, etc...

Might fix my problem.....What a pain!

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