We've had a few students install Windows XP Pro on their personal computers. I discovered this when unknown computer names began appearing in Server Manager (listed as Windows NT 5.1 Workstation). After asking all of our folks that have access to create computer accounts, and getting no ownership of doing so, I was pretty alarmed.
Since then, I have installed WinXPPro on a computer myself and duplicated the issue.
Without being added to the domain, the computer name is displayed in Server Manager. It concerns me that this could happen. Could you shed some light on it for me?
First, this is not specific to WinXP. Anyone can install a NetBIOS capable OS and use your domain in the name field. Windows, Linux (using Samba) will all do this.
Since they are all in the same NetBIOS browsing domain they will show in your Server Manager list, browse list. However, you will not be able to manage them, and they will not be able to manage your systems.
At the time of installation, the various WindowsNT/XP systems install create a unique identifier, I think it is called a SID (Security IDentifier), which is a quasi-random, big number that is unique for all installations. When the OS is installed into a domain and you enter the domains administrator password, the SID derives part of itself from the domain controller. Alternatively you can admit the machine to domain later using server manager, when then stores the SID in the domain database.
Otherwise, welcome to the joys of NetBIOS networking. Can't control it, can't lock it down. If you want to control these type of happenings then you should look at an Active Directory Services implementation which will control this.
Feel free to ask more questions on this one.
This was first published in November 2001