Since few weeks, some websites are suddently unavailable. We are getting a 404 - The web page requested cannot be displayed.

Basically, the only way to fix this is when I restart the DNS client/server on the server. The server is up to date but I did not update the browser since I don't use it on the SBS.

Is anyone have heard of that so far? I'm am clueless again and still working to find a resolution asap.

Best regards and thanks for your precious help!



  • Dell PowerEdge 2950
  • 16GO Ram
  • Dual Quad Intel Xeon 2.83Ghz
  • Microsoft Windows Server 2008 Standard, FE 6,0,6001 SP1 x64
  • JS: Thank you for you answer. This is the one I was lookign for! – user8740 Jul 24 '09 at 15:05
  • Were you originally using Root Hints or Forwarders on the DNS Server? – JS. Jul 24 '09 at 16:25

This is a known bug on Windows Server 2008 DNS Server, including SBS 2008.

You need to use Forwarders on your DNS server instead of Root Hints, or use this workaround.

Windows Server 2008 DNS Servers may fail to resolve queries for some top-level domains

Cause: When the DNS server saves the NS records to the cache, the TTL for the A (Glue) record gets changed to be 1 day. The TTL for the NS Record stays at 2 days. When the A records expire, the DNS server starts returning a "Server Failure" response to the client that issues the dns query.

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  • The description of the bug that you posted does not match the symptoms reported (specially the 404). – bortzmeyer Jul 24 '09 at 15:14
  • The core of the issue is the DNS server and not the web browser, The artice I linked to isnt going to describe errors reported by client software that uses DNS. In this case Internet Explorer (probably). – JS. Jul 24 '09 at 15:41
  • The issue is here again. I did what is listed in the KB Article but no luck. The user is using Safari and there is the error message: Safari cannot find the server. Safari cannot display the following webpage: ping.fm/RiEzN. Safari cannot find server "ping.fm". Once again, when I restarted the DNS Server service, the website is available. – user8740 Jul 24 '09 at 16:02
  • You may need to clear the DNS Client cache on the machine using Safari. If its a Windows machine its ipconfig /flushdns. Also make sue you typed the Registry DWORD name exactly the same as in the article. – JS. Jul 24 '09 at 16:08
  • The Registry Dword has been typed correctly. I'll give heads up with the DNS cache flushing when the issue will be back. For the moment, nothing to declare ;) Thanks a bunch guys! – user8740 Jul 24 '09 at 17:53

A 404 error is usually a not found error. If you are getting an actual 404 error. That response is being given to you from the server you are trying to connect to. So it is possible that DNS is indeed working correctly. If you are getting a non 404 error but the page cannot be found. DNS could be the issue.

Like the post above. Try to ping the FQDN of the site to see what IP is returned. That is the first step. Ping resolves the FQDN via your local DNS server. Ping also tells you if the server is responding. If the name and the IP resolve correctly and the ping responses come back, you should look to make sure the website http server is not hung up or has crashed. With firefox when I go to a non existent web domain I get the error "address not found" (Which is a similar result to incorrect DNS resolution!)

If you are getting a bonafide 404 error, then I would make sure someone has not misconfigured the external HTTP server or determine if the website contents you are looking for still remain on the webserver. I have seen content accidentally deleted in this fashion and a 404 response is what you would expect in this kind of scenario.

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When you're getting one of those 404 errors, drop to a command line and nslookup or ping the domain name to see what IP is being returned. Seeing where that is pointing when it's not working may shed some light on it.

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