1. Check the replication service health on each domain controller in the sites that are in conflict.
2. Identify the source and destination of the replication connection used by the two domain controllers in the site.
3. Perform a replication test with a utility such as the Replication Status Tool to verify accurate communication between the domain controllers.
4. Verify that Active Directory replication is queueing correctly.
5. Look for replication connection objects in the local site and confirm that the cost attribute matches the path cost defined by the administrator.
6. Ensure that the local server has permission to access the remote domain controller.
7. Identify any issues with the network or link that is preventing the replication of data between the sites.
8. Use the repadmin utility to analyze the replication topology and identify possible causes.
9. Use the event viewer to troubleshoot Active Directory replication.