Site Based DC is a nifty feature in ADSelfService Plus that will ensure the changes made by end-users through self-service are updated in Active Directory without any delay. In Site Based DC, you assign a particular set of Domain Controllers to an OU. When a user from that OU resets his password or self-updates his profile information using ADSelfService Plus, the data is quickly updated in the DCs assigned to that OU, in the same order, as configured under Site Based DC settings.
Configuring Site Based DC:
Navigate to "Admin" Tab → "System Utilities" → "Site Based DC"
Select a domain from the drop-down menu. You will see a list of OUs and domain controllers belonging to that domain
Select an OU to see the list of DCs that are assigned to that OU.
Click "Select More DCs" to add or remove DCs from the list
Click on the Up/Down arrow buttons at the top right corner to choose the order in which the DCs will be updated. The first DC in the list will be updated first.
Select the option "Inherit to Child OUs" to apply the settings of parent OUs to child OUs.