Over the past several months, I have written about many of the powerful new features that Microsoft has built into Windows 2000. When fully and correctly implemented, Win2K represents a major change in both form and function. Most of the new features are great, but many are available only when you run Win2K on both the client (i.e., Win2K Professional) and on the server (i.e., Win2K Server) with Active Directory (AD). This limitation is acceptable for those who have fully migrated to Win2K, but most of us will likely find ourselves working with Windows NT 4.0 and Windows 9x clients for some time. Microsoft is aware of this reality and has responded with the Active Directory Client Extensions (aka Directory Service Client—DS Client). In network environments that deploy Win2K Server and AD, the DS Client lets NT 4.0 and Win9x clients take advantage of some, but not all, of AD's features.

For clients that run the DS Client, the software provides three significant features. First, the clients become aware of AD Sites. With access to AD Sites, client machines can locate important servers, such as domain controllers (DCs), on their local subnets. (To learn more about AD Sites, see my December 11, 2000, column). Second, the DS Client lets clients access domain-based Microsoft Dfs roots. Domain-based Dfs roots have several advantages over standalone Dfs roots, including fault tolerance and load balancing. (To learn more about Dfs, see my January 15, 2001, column.) Third, the DS Client lets NT and Win9x clients search AD for information. It doesn’t do you much good to populate AD with information if your users can’t access it.

Despite the additional features that the DS Client provides, NT and Win9x clients continue to miss out on several Win2K features, the most significant of which is Group Policy. In addition, the DS Client doesn't provide support for several powerful Win2K security features, including IP Security (IPSec), Layer 2 Tunneling Protocol (L2TP), and Kerberos.

Client machines need Win2K Pro to take advantage of all of Win2K's features, but the DS Client does open up some functionality for NT and Win9x clients. You can download the DS Client for NT 4.0 from the Microsoft Web site. (To run the DS Client, your NT 4.0 clients must have Service Pack 6a—SP6a—installed.) You can find the DS Client for Win9x in the Win2K Server CD-ROM's Clients\Win9x folder.