In a warm standby application, the active database and the standby database appear in the replication system as a connection from the Replication Server to a single logical database.
The replication system administrator creates this logical connection to establish one symbolic name for both the active and standby databases.
Replication Server maps the logical connection to the currently active database and copies transactions from the active to the standby database.
See Replication Server Administration Guide Volume 1 > Manage Database Connections.
To improve replication performance, you can create alternate connections and alternate logical connections in warm standby environments.