Article ID: 2019500 - View products that this article applies to.
In an Exchange 2007 Environment the Exchange Management Console may try to connect to a non-existing DC/GC, i.e. a DC/GC, which was earlier in the environment, but was later demoted and removed from the environment. An automatic failover to an existing DC/GC in the environment does not take place and the Exchange Management Console may close, showing an error message You will notice this Error in application Log:
Log Name: Application
Description: (PID 5984, Thread 10) Task Get-ExchangeServer writing error when processing record of index 0. Error: Microsoft.Exchange.Data.Directory.SuitabilityDirectoryException: An Active Directory error 0x51 occurred when trying to check the suitability of server 'OLDDC.FQDN.COM'. Error: 'Active directory response: The LDAP server is unavailable.' ---> System.DirectoryServices.Protocols.LdapException: The LDAP server is unavailable.
(PID 11100, Thread 24) Task Get-MailboxDatabase writing error when processing record of index 0. Error: Microsoft.Exchange.Data.Directory.SuitabilityDirectoryException: An Active Directory error 0x51 occurred when trying to check the suitability of server '<FQDN of Your Server>'. Error: 'Active directory response: The LDAP server is unavailable.' ---> System.DirectoryServices.Protocols.LdapException: The LDAP server is unavailable.
The issue even does not go away even if you go into the Exchange Management Console and change the Configuration Domain Controller according to http://technet.microsoft.com/en-us/library/aa998227.aspx
It is correct that the DC, mentioned in the application log is not available. The server may have been demoted, nevertheless Exchange still tries to connect to the unavailable DC.
This obsolete Information is cached in an EMC file in the Windows profile with whom user has logged into the server.
Go to the following location and delete the Exchange Management Console file.
C:\users\<specific user>\AppData\Roaming\Microsoft\MMC\Exchange Management Console
Close EMC and Reopen it.
NOTE: Be aware, that You may loose certain filtering preconfigurations You made for that user.
For certain filter settings of the EMC see the following: http://msexchangeteam.com/archive/2006/10/20/429233.aspx
(http://go.microsoft.com/fwlink/?LinkId=151500)for other considerations.