Exchange Server 2003 and Active Directory
Microsoft Exchange Server 2003 relies entirely on the Microsoft Active Directory directory service for its directory operations. Active Directory provides all mailbox information, address list services, and other recipient-related information. Most of Exchange 2003 configuration information is also stored in Active Directory. System Attendant is the component in Exchange 2003 that is responsible for managing directory access. System Attendant includes various internal components, such as DSAccess and DSProxy, which communicate with Active Directory and cache directory information to increase the speed with which directory information is retrieved and to reduce the workload on domain controllers and global catalog servers.
This section describes the directory access components of Exchange Server 2003, their purpose, their architecture, and how the core technology works. This information can help you maintain directory access and troubleshoot directory access issues. This section discusses the following concepts:
Extension of the Active Directory schema Exchange extends the Active Directory schema and leverages Active Directory for recipient and configuration information.
Differences between domain controllers and global catalog servers A global catalog server is always a domain controller, but the reverse is not always true. The differences are discussed in this section, including why Exchange Server 2003 must communicate with domain controllers and global catalog servers.
Directory Service Access component in Exchange Server 2003 The Directory Service Access (DSAccess) component is an internal component of System Attendant that is used to access and store directory information. DSAccess statically or dynamically detects directory service servers in your organization.
DSProxy component in Exchange Server 2003 DSProxy enables communication between Active Directory and Exchange 2003 computers. DSProxy provides both proxy and referral services to MAPI clients, such as later versions of Microsoft Office Outlook.
SMTP categorizer in the Exchange transport engine The SMTP categorizer must communicate with Active Directory to resolve recipient information and determine message restrictions during message transfer. Although the categorizer relies on DSAccess, it also uses its own mechanism to communicate with Active Directory.
Recipient Update Service Exchange Server 2003 communicates with directory servers to update recipient objects (such as mailbox-enabled user accounts or mail-enabled groups) with e-mail addresses, according to the recipient policies defined for the organization.
**Metabase update service **The metabase update service must communicate with Active Directory to obtain configuration settings that relate to Internet Information Services (IIS) components, such as the Simple Mail Transfer Protocol (SMTP) service and the World Wide Web service. It is the task of the metabase update service to transfer these settings into the IIS metabase.
For more information about planning, designing, and deploying Exchange 2003, see the following guides: