I hope you like a challenge, because I have a rather complicated issue (...that probably has a simple answer!). My machine is an IBM Netfinity 5600 Server with 2 processors and 512 MB RAM. Not sure about the speed of the processors -- I "inherited" this machine. I think they're 500 Mhz each. It currently has Windows NT 4 Server, SP 6 (Ver. 4) installed. It was the PDC in a test lab, but now I want to join it as a BDC to my existing, VERY OLD AND PATHETIC LAN. The reason I want to join it to the LAN is to eventally make it the PDC in this LAN because the hardware is more powerful and updated. Also, I'll eventually upgrade this server to Windows 2000 Server. My existing LAN, also "inherited", is pretty gross. The PDC is an old Digital DECpc XL466d2 running Windows 3.51 Server version 4 (see why I want to upgrade???). I have 3 BDCs: 1 is NT Server 3.50, 1 is NT server 3.51, and 1 is NT Server 4 SP6. My problem: I can't seem to change the Domain name in Network Neighbourhood to join the LAN. It keeps telling me I'm already connected. From the IBM Netfinity: - I made it a BDC on it's old network before trying to connect it to the existing LAN. - I can connect to shared folders on the LAN that I'm trying to connect to. - I cannot get to the Internet (I inserted the same WIN and DNS entries as on the other existing BDCs). - I can see the entire network in Server Manager. - I've tried disconnecting all open connections from the existing PDC that the IBM has to the network then tried changing the Domain (on the IBM) again, but nothing. From the existing PDC: - I've added the IBM Netfinity to the Domain, but can't connect to it ("Access is Denied"). I sure hope someone can help. I've been working on this (on and off) for 2 days. Thanks alot.

"I cannot get to the Internet (I inserted the same WIN and DNS entries as on the other existing BDCs)." What about the IP, subnet, and default gateway... i'm assuming you changed those as well? You could have another protocol other than IP on this machine that's allowing you to browse the network (Netbeui, IPX/SPX) If my memory serves correct, A NT 4.0 Domain controller can not join another domain..You can only rename it.. and that has it's own side effects. If you rename it it's not the same thing. You need to reinstall the OS as a bdc of the domain you are trying to join. Then Promote it to a PDC... then you can upgrade it to WIN2k.

"It was the PDC in a test lab, but now I want to join it as a BDC to my existing" Doing your homework would have saved you hours of lifespan. AD is correct that natively you can not move a PDC to another domain. Flatly you can not move ANY domain controller to another domain period. Only way is to reinstall as a bdc OR buy Upromote which is a 3rd party utility for this purpose. Couple of years back at sys or wininternals.com there was a procedure for using NEWSID to move a bdc to another domain. So you do have some options.

Wanderer is right...YOU CANNOT MOVE PDC's and BDC's from domain to domain...the sids and the account database's get alll screwed over, so it cannot be done. You would have to format the hard drive, plug it into the network, and reinstall windows nt on it, then, make it a BDC...THEN, take your old pdc offline, and promote your new BDC to yoru new PDC, thus, you have a new PDC...cha ching...then...you can demote your old PDC to an BDC, and your all set

I would like to thank all of you for responding so quickly. We had received a message box telling us that we could not change the domain on the 'this' backup domain controller. You guys have confirmed what we thought.

FYI Moving a BDC is possible using newsid from sysinternal.com