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USE_NOTIFY Domain Replication
Whether to use notification or a replication interval to replicate across a site link is configured site link. If all your sites are in the same site link configuration is simple, but if you have several sites links, in a hub-spoke topology e.g., you will have to configure each site link.
You can make the change using any tool able to write to Active Directory attributes. I will use Active Directory Sites and Services since that is the easiest way. The change itself requires Enterpise Admin level permissions.
Find the site link you want to change, right click and select Properties.
Select the Attributes Editor tab.
Find the options attribute (make sure that you display all attributes regardless of whether they have a value or not, since this attribute does not have a value by default).
Set the value of the options attribute to 1. Notice how you will now have an explanation behind the 1 value indicating that you have configured the link to use notifications (USE_NOTIFY).
Replicate this change to all DC manually or wait for regular scheduled Active Directory replication.