DNS and Server 08

J.B

J.B

J.B

Soldato
Joined
16 Aug 2006
Posts
5,924
Hey guys, hoping someone will be able to help, or at least give a clue!

I have a DNS server running as part of our domain. Has a couple of entries to point to our mail server etc.

Every so often (maybe once a week) some sites will stop working. Not all sites, for example right now I can get on OcUK and others but cant access bbc or google on any machine.

I do an nslookup and ping on the domains that arent working and they are not even being ressolved to an IP.

The only way to fix it is by clearing the cache on the DNS server from MMC.
Any thoughts?
 
We have had this, its a known issue that ms are aware of - i can't remember if there's a fix or not, not at work this week, or i would ask what fixed it or not,
 
AndyC said:
We have had this, its a known issue that ms are aware of - i can't remember if there's a fix or not, not at work this week, or i would ask what fixed it or not,
Click to expand...

Interesting, I did google around but didnt find much of interest.
 
Its just set to standard configuration with the addition of a couple of record entries.

We're not using any conditional forwarders if thats what you mean.
 
What I think iaind is getting at is how are you doing your external lookups (i.e. to google.com) are you using a standard forwarder that forwards DNS to unknown names for external resolution (which is pretty standard) or are you using root hints, etc.



M.
 
Which external DNS servers are you forwarding to, the ones provided by your ISP? I had a lot of issues using my ISP's (Virgin Media) DNS servers, so I switched to the ones provided by OpenDNS and haven't had any problems since. The issues I experienced were very similar to yours - google and other mainstream sites being extremely slow to resolve or completely failing to resolve.
 
OK I'm going to sound really noobish but I cant remember were to find where the DNS forwarding for an unknown domain.

But I'm guessing they are.

I would have thought it was a problem with our local DNS server as when I clear the cahce on our server it works again.
 
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Just had a thought, do you run mac's? it rings a bell, a certain version of the mac os and the way it looked up dns caused a fault on the 2008 dns service after x amount of time, i could be wrong thou,
 
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I'd suggest changing the primary forwarder as well it definitely sounds like an issue resolving DNS by your ISP. Perhaps forwarding it to one by your ISP and the second to open DNS or such like.



M.
 
Not sure how your accessing the net, but if you have a proxy server then my preferred method for doing this would be to install DNS on the proxy server, configure root hints and give it the ability to go out through your firewall for dns requests then configure the proxy servers nics to use the local dns server. Add your domain zone to it too so that the proxy will still be able to find DC's/other services

This way your not at the mercy of ISP caches or external dns servers going down, at the same because you are doing it on a proxy you are avoiding giving other systems the ability to resolve internet addresses which can be preferred if you want to control what they are able to connect to.
 
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