Active Directory Updates
Replication of updates is triggered when a user (or an application or service) updates a particular object or objects on a domain controller. When an update occurs, a timer is started such that changes are collected for a set period, after which the replication engine notifies adjacent domain controllers in the replication topology within the site (in other sites if notification between sites is enabled). After it has been notified that there are changes to be collected, the destination domain controller contacts the source domain controller to request the changes. Replication between sites is typically performed on a scheduled basis: A domain controller requests changes from domain controllers in other sites according to a configurable schedule.