15.1. Joining a Domain: Windows 200x/XP Professional
Microsoft Windows NT/200x/XP Professional platforms can participate in Domain Security. This section steps through the process for making a Windows 200x/XP Professional machine a member of a Domain Security environment. It should be noted that this process is identical when joining a domain that is controlled by Windows NT4/200x as well as a Samba PDC.
STEPS TO JOIN A DOMAIN
The screen capture shown in Figure 15.4 has a button labeled More.... This button opens a panel in which you can set (or change) the Primary DNS suffix of the computer. This is a parameter that mainly affects members of Microsoft Active Directory. Active Directory is heavily oriented around the DNS namespace.
Where NetBIOS technology uses WINS as well as UDP broadcast as key mechanisms for name resolution, Active Directory servers register their services with the Microsoft Dynamic DNS server. Windows clients must be able to query the correct DNS server to find the services (like which machines are domain controllers or which machines have the Netlogon service running).
The default setting of the Primary DNS suffix is the Active Directory domain name. When you change the Primary DNS suffix, this does not affect domain membership, but it can break network browsing and the ability to resolve your computer name to a valid IP address.
The Primary DNS suffix parameter principally affects MS Windows clients that are members of an Active Directory domain. Where the client is a member of a Samba domain, it is preferable to leave this field blank.
According to Microsoft documentation, "If this computer belongs to a group with Group Policy enabled on Primary DNS suffice of this computer, the string specified in the Group Policy is used as the primary DNS suffix and you might need to restart your computer to view the correct setting. The local setting is used only if Group Policy is disabled or unspecified."