The ID Server is a Replication Server that registers all Replication Servers and databases in the replication system.
In addition to the usual Replication Server tasks, the Replication Server acting as the ID Server assigns a unique ID number to every Replication Server and database in the replication system. The ID Server also maintains version information for the replication system. Otherwise, the ID Server is like any other Replication Server.
Because of these requirements, the ID Server is the first Replication Server that you install and start when you install a replication system. If you have only one Replication Server, or if you are installing Replication Server for the first time, then that Replication Server is also the ID Server. If you are adding a Replication Server to an existing replication system, you must know the name of the Replication Server in the system that is the ID Server.
The ID Server must have a login name for Replication Servers to use when they connect to the ID Server. The login name is recorded in the configuration files of all Replication Servers in the replication system by the rs_init configuration program when you are setting up and managing the replication system.