restoring AD onprem

Question

Hello,

Let say i have 2 domain controller (primary and secondary) and all 5 FSMO roles handle by PDC.

The i have hardware issue on my PDC and must be restored from our backup (image backup using veeam). Let we assume the restoration need time until 48 hours. While the restoration still in progress, we do some changes on the Secondary DC (reset password, create user for example) so daily operational is not disturb.

When the restore is done and the PDC is running again, what will happened with the active directory?

Will the Secondary DC replicate their data to PDC, or PDC will replicate to Secondary DC and all changes when the Primary DC will be ignored?

Answer 1

Hello,

In the scenario you described, when your PDC is restored and back online:

The Secondary DC will replicate data to the PDC. Any changes made on the Secondary DC (such as resetting passwords, creating users, etc.) while the PDC is offline will be replicated to the PDC.

The PDC will not overwrite changes on the Secondary DC: The PDC will not overwrite new data on the Secondary DC, but will receive new data from the Secondary DC.

Active Directory will automatically resolve any potential conflicts. Normally, newer changes on the Secondary DC will be retained, and the older data on the PDC will be updated.

It is recommended that after the Primary DC is restored, you can use the command repadmin /showrepl to check the synchronization status to ensure that all changes have been synchronized correctly.

Best Regards,

Yanhong Liu

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