To achieve bidirectional replication, first define two unidirectional connection objects. The KCC periodically creates connections to maintain directory connectivity without manual intervention. However, you can manually create connections. If you create a connection that is identical to the one that the KCC would create, the KCC does not create an additional connection and does not delete any manual connections. A connection object exists under the NTDS settings object of the server that is the destination of the replication traffic.
Replication is always pull-based.
A connection object is between two specific servers. A connection object does not restrict the partitions that can be replicated between the two servers. The directory replicates all partitions that are common between the two servers. The site link allows the administrator to assign the cost and transport for replication. This procedure defines parameters for replication.