If you happen not to be able to manage your exchange infrastructure and receive this error in the Exchange Management Console:
“An Active Directory error 0x51 occured when trying to check the suitability of server ‘OLD_DC_NAME’. Error: ‘Active Directory response: The LDAP server is unavailable.'”
every time you try to read information that are related to the configuration the causes can be two:
- The exchange organization is actually pointing to the old domain controller (and this is a problem because some services may not work). In this case, you can edit this setting within the EMC (if you can) going in the properties of the “organization configuration”, from there, you can specify a new reference domain controller; alternatively, if the EMC does not allow you to do that you can specify a new DC with this powershell command:
Set-ADServerSettings -PreferredServer newdcname.domain.local
- it's just a problem of the EMC cache, then everything is working properly but your stupid EMC has cached the information that it needs to connect to the old DC. In this case you simply delete the file “Exchange Management Console” that is in C:UsersUserNameAppDataRoamingMicrosoftMMC
