If Active Directory is out of sync, you can force a pull or push replication event from a domain controller.
Push (push all changes from the domain controller to other domain controllers):
repadmin /syncall /APeD
Pull (pull all chnages from other domain controllers to this domain controller):
repadmin /syncall /AeD
Explanation
The CLI flags are:
/A: All Partitions/e: Enterprise – Cross site replication/D: Identify servers by distinguished name (in the output)/P: Push