Hi all,
To prevent the event ID 4521 occuring on all the domain controllers, we may need to delete the DomainDNSZones partition from the Active Directory. Meanwhile, please make sure we don't have any zones under that Partition, otherwise the zones will also be deleted.
Please backup the domain controller before delete the DomainDNSZones.
Backing Up Domain Controllers
Backing Up Domain Controllers
Then you may refer to the following steps to delet the DomainDNSZones
How to Delete the DomainDNSZones
Create or delete an application directory partition: Active Directory
Please Note: Please do not create another partition with the same name until the servers which hold this partition have had an opportunity to remove it. This will occur when knowledge of the deletion of this partition has replicated throughout the forest, and the servers which hold the partition have removed all the objects within that partition.
After the DomainDNSzones parition was removed from the Active directory. Let it replicate on all the domain controller.
Then run the following command.
net stop dns
net stop netlogon
ipconfig/flushdns
net start dns
net start netlogon
ipconfig/registerdns
Reboot the DC after that.
Then, please check if there will be any event ID 4521 re-occur on the domain controllers.
Hope it helps.