The Active Directory service uses Domain Name System (DNS) for name resolution. However, in a Microsoft Windows 2000-based forest or in a Microsoft Windows Server 2003-based forest, programs that depend on the NetBIOS namespace may require Windows Internet Name Service (WINS).
WINS provides a dynamic replicated database service that can register and resolve NetBIOS names to IP addresses that are used on a network. WINS is required for applications that call the NetServerEnum function. This function depends on NetBIOS. Programs that call the NetServerEnum function include Cluster Administrator, SQL Administrator, SNA Server, and more. Additionally, WINS is required to populate Network Neighborhood on every computer.
In a forest that contains more than one domain, you must use unique NetBIOS names for all the computers in the forest, regardless of the domain to which the computer belongs. This is true because NetBIOS name resolution will be required between the domains.
When you design an Active Directory implementation that is based on a single forest, and you include WINS forest-wide, all NetBIOS names must be unique in all the domains that belong to the forest. If a NetBIOS name is used on a computer in one domain, and you try to use the same name on another computer in another domain, you receive a warning message that the name is already being used.
For example, consider the following scenario:
- The Active Directory forest contains the following two domains, CompanyA and CompanyB.
- WINS is configured to replicate between the two domains.
- CompanyA installs a server, configures the server to use WINS, and names the server \\payroll.
- CompanyB installs a server, configures the server to use WINS, and tries to name the server \\payroll.
In this scenario, the server in the CompanyB domain will try to register itself with WINS, and WINS will detect that the NetBIOS name is already being used. The WINS server will make sure that the computer in the CompanyA domain that first registered the NetBIOS name \\payroll
is still available and is still using the name. The WINS server then notifies the server in the CompanyB domain that the name already exists on the network, and a warning message is received by the person installing the server. A different NetBIOS name must be used for the server in the CompanyB domain.
Although you may be able to configure a separate WINS infrastructure that does not replicate between domains in each domain, NetBIOS name resolution will likely be required between the two domains. This is also true if the domains contain Windows-based computers that are running operating system versions earlier than Windows 2000. Windows 2000-based computers in an Active Directory forest use DNS for name resolution, but versions of windows earlier that Windows 2000 may require WINS for name resolution between the two domains. In this scenario, it is best to implement a naming convention strategy that prevents duplicate names.