flushing dns on domain controller

Any suggestions on how to force my DC (which is also my primary internal DNS server) to grab the latest public DNS entries for my websites?  

I recently changed a public IP address for one of our websites.  6 hours later, externally, a ping returns the correct, new address.  However, internally, a ping still returns the old address.  Our firewall (on the perimeter of our network, obviously) returns the correct, new address when pinging the site, so it seems very likely that the issue is with my DC... no?

I've checked my forward lookup zones for any manual entries that might conflict, and there aren't any.  I've run ipconfig /flushdns on the DC (and backup DC), as well as the client workstations.  Any ideas?  Thanks!
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cuiincAuthor Commented:
update: my backup DC returns the correct IP address on a ping.  my primary DC does not, nor do my clients.  any idea on why this would be?
Lee W, MVPTechnology and Business Process AdvisorCommented:
Flush DNS.

IPCONFIG /FLUSHDNS form an administrator level command prompt.

And make sure you haven't set HOSTS file entries or custom DNS records in your DNS server (though it really sounds like a cache issue).

And a reboot should fix it too.
In the DNS Management console, right-click on the server and select "Clear Cache".

As Lee mentioned, rebooting will clear this too.

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