The Exchange Server Directory

The Microsoft Exchange Server directory contains information about mailboxes, distribution lists, servers, topology, and system configuration information. It provides a unified, structured view of all users and resources within the Microsoft Exchange Server environment.

The directory is structured as a hierarchy of objects. Each object contains attributes in which information about that object is stored. Objects may be container objects, in that they contain other objects, or they may be leaf objects, in which case they do not contain other objects. Container objects may contain other container objects.

This hierarchy can be thought of as similar to the file system.

• The file system has a root, folders which contain files or other folders. The Exchange directory has a root object called the Organization object.
• Like file system folders, the Exchange directory has containers. These containers can hold sub-containers.
• In these containers are directory objects, such as mailboxes, distribution lists, servers, or configuration objects.
• Each object has a set of attributes that are dictated by the object class, named and positioned in accordance with the schema for that object and its container.

The LDAP protocol is natively implemented within the Exchange Server directory service. The LDAP server runs within the DSAMAIN process (DSAMAIN.EXE) on the Exchange Server. LDAP monitors TCP port 389 (or 636 for LDAP over SSL) and accepts incoming LDAP requests. The LDAP server handles these requests and ships the response back to the client. While Microsoft Exchange Server 5.5 supports LDAP version 3, Exchange Server 5.0 supports LDAP version 1.

LDAP version 3 includes many updated features, such as adding, modifying, and deleting directory objects from clients with appropriate permissions. LDAP version 1 was only capable of searching for directory objects and returning attributes.

To take full advantage of all the functionality provided in ADSI, you must have ADSI client programs attach to an Exchange 5.5 Server. This does not mean you need to upgrade all of the Exchange 4.0 and 5.0 servers within your organization before you are able to take advantage of the features of ADSI. Because Exchange Servers within a site have a multi-master directory replication relationship, you can have one Exchange Server in the site that handles LDAP version 3 requests and then replicates the changes to other servers in the site.

For information on configuring the LDAP service for an Exchange Server, refer to the Microsoft Exchange Server 5.5 Books Online.