What do Active Directory sites do?
Active Directory sites govern access and replication.
Active Directory's DClocator
process allows for devices to find the nearest domain controllers. By default, these would be the domain controllers in the current Active Directory site where the device resides. The way the device knows in which site it resides is derived from its Internet Protocol (IP) address, which matches a subnet, as defined for the Active Directory site.
When there are no domain controllers in an Active Directory site, the site link costs define the nearest domain controllers to DClocator
. The domain controllers in the site connected with the lowest cost will be returned to the device.
Domain controllers in different Active Directory sites replicate partitions over the same Active Directory site links through bridgehead servers; these are domain controllers that take on the additional role of replicating over the site link to the bridgehead server on the other...