Replication isn't perfect. It depends on the MTA, messaging connectors, directory replication connectors, and trouble-free physical links to work properly. Here are some tips for solving common problems.

Accelerating Replication
When you create the directory replication connector, site names don't immediately appear in the connector's Sites tab. Until Exchange discovers these names, replication cannot occur. If you don't want to wait for the new sites to become visible through the Exchange interface, you can accelerate the process. Go to the Exchange Administrator window and drill down to the name of the server where you have configured the directory replication connector. From the right pane, click on the Directory Service object. On the General tab, click Check Now to check Knowledge Consistency. This action forces recognition of the new replication link with any new servers. When you can see the sites in the Sites tab, you can request directory updates through this window by clicking Request Now. This technique is a quick way to override the Schedule tab settings.

Troubleshooting Stalled Replication
Directory messages sometimes get stuck on the source server and aren't transmitted to the destination server in the remote sites. To view stuck messages, from Exchange Administrator, go to the server name, and in the right pane double-click Message Transfer Agent and select the Queues tab. If you have DS messages that refuse to budge out of the Originator column, replication is stalled. Typical fixes include checking whether the MTA is functional on both servers and ensuring that the messaging connector is configured correctly and the physical link between the servers is operational. Rarely is the directory replication connector a problem, because messages don't pass through this connector. NT logs directory replication errors to the NT Event Viewer in the Application Log. When you're troubleshooting in the Event Viewer, look for the references to the Directory Replication Agent component.

Recognizing Size-Limit Violations
Size limits the mail administrator configures on the MTA or the messaging connector can stop directory messages from being transmitted because Exchange batches directory messages, and a batch can exceed the size limit.

Forcing Objects to Appear
Sometimes Exchange Administrator doesn't reflect new objects in the Exchange hierarchy even when replication is current throughout the organization. This problem can occur when the monitor has not refreshed itself. Before troubleshooting why objects don't appear, press F5 to force a refresh. If you still cannot see the object, try closing and reopening Exchange Administrator. This action usually fixes this minor but annoying bug.