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.