XADM: Directory Replication Takes Too Long

This article explains why, depending on the Directory Replication topology, the time required to replicate directory changes to all parts of a Microsoft Exchange Organization may be several days.

Consider the following two Directory Replication topologies.

Topology A: Hub

Topology B: Cascade

In each of the above topologies, the arrows indicate a directory replication connector. Assume that each connector is scheduled to replicate at one time during the day.

In Topology A, if a new mailbox is added to Site X, the maximum delay for that directory entry to be propagated to all the other Sites would be 2 days (one day for each directory replication connector hop).

In Topology B, if a new mailbox was added to Site W, the maximum delay for that directory entry to reach all the other sites (specifically Site Z) would be 3 days.

Hence, the time required to propagate directory changes to all sites in an Exchange Organization depends on the replication schedule as well as the number of hops involved and the number of hops depends on the Directory Replication Topology.