Microsoft 1 manual Domain controller, Domain mode, Domain Name Services DNS, Domain tree DSAccess

Glossary 101

Domain controller

A server that can authenticate users for a domain. There must be at least one domain controller in each domain within the forest. Each domain controller holds a complete replica of the domain naming context that the server is in and a complete replica of the configuration and schema naming contexts for the forest. A domain controller can be promoted and demoted through the Dcpromo utility.

Domain mode

An Active Directory domain can be in either mixed mode or native mode. In mixed mode, the domain is restricted to limitations (such as 40,000 objects) imposed by the Windows NT 4.0 domain model. However, Windows 2000 domain controllers and Windows NT 4.0 backup domain controllers can seamlessly co-exist within the domain without problems. Switching to native mode, which is irreversible, allows the directory to scale up to millions of objects and overcome the constraints of the earlier SAM, but requires that all domain controllers be upgraded to Windows 2000. A domain in native mode allows for rich group creation and nesting, which is advantageous to Exchange 2000.

Note that Windows NT 4.0 member servers can still exist within a native-mode domain. Additionally, clients do not have to be upgraded before the domain mode is switched.

Domain Name Services – DNS

A major standards-based protocol that allows clients and servers to resolve names into Internet Protocol (IP) addresses and vice versa. Windows 2000 extends this concept even further by supplying a Dynamic Domain Name System (DDNS) service that enables clients and servers to automatically register themselves in the database without needing adminis- trators to manually define records.

Domain tree

A collection of domains that have a contiguous namespace, such as microsoft.com, dog.microsoft.com and cat.microsoft.com. Domains within the forest that do not have the same hierarchical domain name are located in a different domain tree. A disjoint namespace is the term used to describe the relationship between different domain trees in the forest.

DSAccess

The Exchange 2000 component that provides directory lookup services for components such as Simple Mail Transfer Protocol (SMTP), Message Transfer Agent (MTA), and the store. Client requests use the DSProxy service for directory access.

DSProxy

The Exchange 2000 component that can proxy (and refer) Messaging Application Pro- gramming Interface (MAPI) directory service requests from Outlook clients to Active Directory for Address Book lookup and name resolution.