DNS Not resolving to correct site

ComexIT used Ask the Experts™
We had a issue last week where client machines were pointing to a old version of a website on the old external web server, we cleared the cache off the internal DNS servers and also did a IPconfig /flush dns and this did resolve but it has appreared again today ..... any ideas ? Both DNS on internal are W2008 r2 and external are ISP / Google
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Seth SimmonsSr. Systems Administrator

stop using external dns for name resolution
seems like public dns has wrong A record if external resolution is pointing to the old server
fixing the A record should resolve it though still no reason to be using external dns servers
Hi ComexIT,

From your post, it sounds like you have all your internal machines using the Win2008 server for DNS lookup, and the server is then forwarding queries firstly to your ISP, and if that fails, to Google.

I am guessing that when you say that ' it has appreared again today' you mean on the client machines (which is where the issues originally manifested).

You stated that you 'cleared the cache off the internal DNS servers and also did a IPconfig /flush dns' and that worked at least initially.

Did you also do that on the client machines that are resolving incorrectly?  If not, it could be cached lookups on the local machine.  I always prefer to reboot after clearing the local caches too, although not strictly necessary.

If you have already done that, also check that the local machine does not have the hostname / IP hardwired into its HOSTS file, and also check for that on the DNS server.

Once you have checked all of the above, I suggest you do a manual lookup using NSLookup on the client machine (which should return a result from the DNS Server) and then the DNS Server (which should return a result from your ISP).

If you trace back to the issue being at your ISP, then try (temporarily) changing the external DNS from your ISP to something else (Google is fine), and then redo the manual test.

If Google is also resolving the hostname incorrectly, then it implies your DNS host has incorrect records.

You can check that by forcing your manual lookup to use their DNS server (once you are in NSLookup, type 'server') replacing with your DNS hosts nameserver, then redo the manual lookup.  If you still get incorrect resolution, you'll need to update your DNS host's records, or get them to do it for you.



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