directory system agent (X.500) (DSA)

A Directory SystemAgent (DSA) is a directory server in a directory service( DS) according to X.500.

As part of the Directory Information Base( DIB), it is responsible for the directory system of an individual organization or for an organizational unit and answers the requests of the Directory User Agents( DUA). Communication between the Directory User Agent and the Directory System Agent is accomplished using the Directory Access Protocol( DAP).

Components of the directory system according to X.500

The Directory System Agent contains the actual directory information. It can communicate with other Directory System Agents and have copies of parent DSAs. When a Directory User Agent (DUA) makes a request, the Directory System Agent contacts other DSAs.