Understanding Exchange Administration Architecture


Topic Last Modified: 2005-04-21

Exchange 2003 uses Active Directory to store and share information with Windows. Therefore, all the directory information that you create and maintain in Windows, such as organizational unit structure and groups, can also be used from Exchange.

The Active Directory schema can be extended to include custom attributes and object types to centralize and minimize data administration, and also to make data available to applications that can access Active Directory information. In fact, when you install your first Exchange server, Exchange 2003 extends the Active Directory schema to include Exchange-specific information. Extending the schema affects the whole forest and, depending on the size of Active Directory, may take a significant amount of time to complete.

Because Active Directory serves as a single-source directory for all the objects in your organization, Exchange uses this information to reduce administrative overhead. With Active Directory, you can store and organize information about users, such as names, e-mail addresses, and phone numbers. This information is stored as attributes of the user object. Exchange and other applications can use this information. For example, the address lists to which a recipient belongs are written as values to the ShowInAddressBook attribute in that recipient's Active Directory object. To create address lists, Exchange performs Lightweight Directory Access Protocol (LDAP) queries on each of these objects and retrieves the information stored in the ShowInAddressBook attributes.

Because Exchange 2003 relies on Active Directory, make sure that you are familiar and comfortable with Active Directory terminology, structure, and navigation. For a comprehensive overview of Active Directory, review the documentation that came with your copy of Windows.
Microsoft Exchange Server version 5.5 and earlier do not use Active Directory. If your messaging topology is in mixed mode (contains both Exchange 2003 and Exchange 5.5 or earlier), you can still use Active Directory by using Active Directory Connector (ADC) to replicate directory information between the Exchange 5.5 directory and Active Directory.