I have a PDC that logically serves as the DMB. Recently it is failing to send updates to the backup browsers. After so many failed attempts those backup browsers stop their services and the domain itself is unavailable. The only remedy I have found as a stopgap measure is rebooting the PDC.

My PDC is multihomed (which according to Microsoft' KB could be an issue for acting as DMB) but has been for the past 6 years. We never had problems like this until the past several months. And the scenario is getting progressively more frequent. My local BDC is also multihomed so I can't see promoting it to a PDC to address the issue.

I have gone into the PDC's registry and set "IsDomainMaster" to False. And I have gone into Windows 2000 hosts and get "IsDomainMaster" to True to move things over to another host. No luck. The PDC still takes over being DMB. And I have gone into the PDC's interfaces and disabled the Workstation service, WINS, etc. on the external NIC so that only the internal NIC is enabled for providing the DMB services. Still no luck.

To reiterate, the pattern is that over time the other backup browsers fail to receive updates and turn their services off. And the PDC doesn't correct itself until I reboot it.

Suggestions? Until I finally migrate to Windows 2003 Server and retire this 6+ year old PDC

Do you have any server in your farm that is not multihomed and can be promoted to a PDC?  That may be your only hope.  I had this issue when we upgraded our network to Windows2000 (we are since at Windows2003).  Our PDC (when our network was NT4) was a multihomed server.  When we upgraded this to Windows2000 and then upgraded the rest of our servers we had browsing issues.  We had to do what you did by disabling the browsing service and changing the "IsDomainMaster" to false (Microsoft Article#191611). I was then able to get another domain controller that was not multihomed to become the master browser.  So the point is to get a server that is not multihomed up and running. This would hopefully resolve your browsing issue.

Good luck.

Thanks for the info. When I say multihomed I don't mean with multiple NIC's on the same local networks. One NIC is for the internal private network and the other NIC is for the external public network. Plus I disabled WINS items from binding to the external NIC. It's strange that this configuration worked fine for 6 years until just recently. I've added a few Win2K member servers the past two years or so, but that's about it in terms of server changes.

Here's a quick question. Since I haven't done it for so long I can't recall. If I want to swap roles between the PDC and a BDC while both are online, through Server Manager I demote the PDC and then promote the BDC, correct? I would like to do this without service interrupting (i.e. - reboots).

My BDC is multihomed, but it has the second NIC physically disconnected from the network (i.e. - no cable attached) and doesn't have any WINS items bound to that adapter. So in a pinch I was thinking about using it as the PDC.

What's strange is from the PDC if I try to ping one of the client workstations by name it appears to try to go out the external public NIC to resolve the hostname. It can't so the pings fail. One change I made about 3 months ago now was I had trouble with the external network due to an ISP issue. One troubleshooting step I did was reverse the IP addresses bound to the two adapters in the PDC. The private IP was originally bound to the first NIC and the public IP was originally bound to the second NIC. I reversed them where the public IP now is on NIC #1 and the private IP is now on NIC #2. But I reversed the WINS bindings so the items are still only bound to the private IP NIC.

Maybe I can swap these IP's back as something to try? I've tried tweaking the registry settings for the browser service, restarting the browser services when they eventually fail, retarting WINS and Netlogon on the PDC, etc.

This is definitely a pain...

You would promote the BDC to a PDC (this would automatically demote the current PDC.

On the BDC question, just as long as there is nothing plugged into the 2nd NIC you should be fine.  I'm not sure on your other questions.  One thing that may have caused the browsing issue is the Windows2000 Member servers (because the OS is higher).  What you may need to do on the Windows2000 Member servers is do the registry thing (IsDomainMaster=False) and disable the "Computer Browser" service.  

I might look into the promotion scenario if my last attempt at fixing this doesn't work. I found a post on Experts Exchange (http://www.experts-exchange.com/Networking/WinNT_Networking/Q_21467524.html) that had a final solution that supposedly involved disabling the XP clients' AutoEnrollment feature. Since all 30-odd of my XP clients aren't part of any AD tree this AutoEnrollment could cause issues with the Computer Browser service not being able to provide timely enough responses due to a storm of AutoEnrollment attempts hitting at the same time each day.

Logically this makes sense, as the browsing dies around the same times each day (10 AM and 4 PM). And according to what I read the AutoEnrollment attempts to automatically resolve at regular intervals. We'll see how it goes today...

I switched off AutoEnrollment on the XP boxes but the problem still happened again. At this point I have looked and looked but still can't find anything to explain what's going on. Next stop will be promoting the BDC to PDC. Hopefully this doesn't result in some odd disaster

Just as long as your BDC is robust enough you shouldn't cause your network any issues.  

Here is a link to a thread I posted over in the Windows 2000 forum on this site --> http://www.tek-tips.com/viewthread.cfm?qid=1259840&page=1. It seems as if my issue has been resolved or at least things have improved. In case anyone else runs into this improbable situation I figured to spread the word. I know I have been frustrated trying to research a problem only to find a thread posted in some newsgroup or support forum where the final outcome was never posted...

Congrats on your find.  Sorry I couldn't be more help