Replication is a data synchronization mechanism that ensures that updates made to a database are automatically duplicated to other servers.
Replication improves data availability when unforeseen or planned outages occur and improves search performance by allowing client requests to be distributed across multiple servers.
By default, all Directory Server instances participating in replication are writable so that LDAP clients can perform updates at any of these Directory Server instances. These updates are automatically propagated to the other servers in the background in the same order as the updates were entered. The replication process flow is designed to immediately propagate changes to the other replicas in the topology with little or no latency.
The following figure demonstrates the basic flow of replication.