I have an annoying problem with SBS 2008. Everything was fine till I authorized external DHCP running on Linksys router. Now I have that kind of situation where I think everything must be fine but it isn't. Now DNS records of computers in domain aren't updated. The corresponding option is enabled in DHCP server's configuration, however it has no effect. I don't see anything in logs, too. I've tried everything - even removing that DHCP server from network. Now some computers get IP from DHCP, and some don't. It's very strange thing. Also, I've checked if it was a hardware problem and it must be something different. I think it's releated to that empty logs. Ah, and before authorizing that DHCP on Linksys, that on SBS 2008 was crashing with message about other unauthorized DHCP servers in the network, but strange thing - everything was fine. Any ideas?

  • Strangely, DNS updating fixed itself. Only problem now is DHCP not assigning IP's to every computer, like it should. – user39810 Dec 13 '10 at 12:23

If you enable DHCP on the Linksys then you will get no DNS updates on the SBS because it will no longer be involved in the process. You shouldn't have more than 1 DHCP server on your network otherwise they will conflict.

  • Yeah, I don't have currently any other DHCP server than on SBS 2008. The problems started when I removed it. Currently updates works like they should, however adresses aren't leased to all clients. – user39810 Dec 13 '10 at 15:21
  • is your scope authorised? do you have enough addresses in it's range? are the machines on the same local network? – JamesRyan Dec 13 '10 at 15:48

Please see my question, I think I had the same initial issues as you where on 2008 DNS Changes to DHCP assigned hosts were not seen/updated. The commented KB fixed this issue.


In terms of DHCP not assigning new leases. Check to make sure your scope is infact Authorised, the DHCP server service is started. Windows WILL let another DHCP server win everytime and stop it's own service.

It is worth checking your event logs to see if the DHCP server is reporting any warning or errors, you might also find that your scope is full.

I hope this helps, let me know if you have any further issues.


Problem is now resolved, it was very simple. I discovered that someone connected a cable from one switch to another switch, this was the problem why adresses weren't leased.

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