Directory System Agent

The directory system agent (DSA) is the process that provides access to the store. The store is the physical store of directory information located on a hard disk. In Active Directory, the DSA is part of the local system authority (LSA) subsystem in Microsoft® Windows® 2000. Clients access the directory using one of the following mechanisms supported by the DSA:

• LDAP clients connect to the DSA using the LDAP protocol. LDAP is an acronym for Lightweight Directory Access Protocol. Active Directory supports LDAP 3.0, defined by RFC 2251, and LDAP 2.0, defined by RFC 1777. Microsoft® Windows® 2000 clients (and Windows 95 and Windows 98 clients) with Active Directory client components installed use LDAP 3.0 to connect to the DSA.
• MAPI clients such as Microsoft® Exchange connect to the DSA using the MAPI remote procedure call interface.
• Windows clients that use a previous version of Windows NT connect to the DSA using the Security Account Manager (SAM) interface.
• Active Directory DSA's connect to each other to perform replication using a proprietary remote procedure call interface.