Directory System Agent

A Directory System Agent (DSA) is the element of a X.500 directory service that provides User Agents with access to a portion of the directory (usually the portion associated with a single Organizational Unit).

Active Directory

In Microsoft's Active Directory the DSA is a collection of servers and daemon processes that run on Windows 2000 Server systems that provide various means for clients to access the Active Directory data store.

Clients connect to an Active Directory DSA using various different communications protocols:

• LDAP version 3.0 — used by Windows 2000 and Windows XP clients
• LDAP version 2.0
• Security Account Manager (SAM) interface — used by Windows NT clients
• MAPI RPC interface — used by Microsoft Exchange Server and other MAPI clients
• A proprietary RPC interface — used by Active Directory DSAs to communicate with one another and replicate data amongst themselves

References

• "Platform SDK: Active Directory: Directory System Agent". MSDN. September 23. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
• "Active Directory: Active Directory Diagnostics, Troubleshooting, and Recovery: Summary of Active Directory Architecture: Directory System Agent". Windows 2000 Resource Kit. September 23. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
• "X.500: Directory Access Protocol (DAP)". September 23. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)

RFCs

• RFC 2148 — Deployment of the Internet White Pages Service