The directory server replication model is a loosely consistent, multi-master model. In other words, all directory servers in a replicated topology can process both read and write operations.
Replication is built around a centralized publish-subscribe architecture. Each directory server communicates with a central service, and uses the central service to publish its own changes and to receive notification about changes on other directory servers. This central service is called the replication service.
The replication service can be made highly available by using multiple server instances running on multiple hosts. Within the replication architecture, a server instance that provides the replication service is called a replication server. A server instance that provides the directory service is called a directory server.
The topics in this section describe the replication architecture and the various elements that make up this architecture.