We have recently created a new Active Directory and Exchange 2016 environment. The setup consists of the following:
AD01-GC Domain Controller (Windows Server 2012 R2)
AD02-GC Domain Controller (Windows Server 2012 R2)
AD03-GC Domain Controller (Windows Server 2012 R2)
EXCH01-Exchange 2016 Server (Windows Server 2012 R2)
Recently, when accessing the ECP the performance has been very slow with lots of "Please wait spinners". In addition, the "mailbox delegation" section of the "Edit User Mailbox" fails to load.
Yesterday I was able to get the following error popup in ECP complaining about AD02:
"Active Directory operation failed on <domain controller> This error is not retriable. Additional information: Insufficient access rights to perform the operation.
Active directory response: 00002098: SecErr: DSID-03150BB9, problem 4003 (INSUFF_ACCESS_RIGHTS), data 0
The user has insufficient access rights."
After investigating AD01/AD02/AD03/Exchange and not discovering any anomalies in the error logs I decided to shutdown AD02 and to my surprise the Exchange ECP returned to it's normal state.
I am perplexed as to what might be causing this and would greatly appreciate some insight.