i have a problem with one laptop running Windows 7 Pro.
The DHCP server (2008 R2) is configured with a scope of 20 addresses and every address is mapped to a specific laptop via reservations.
Within the scope options, 006 DNS is configured for our two internal DNS servers. (We arent on a Domain- only a workgroup).
The 006 DNS scope option used to point to two different external DNS servers.
One laptop out of the 20 keeps reverting back to the ip addresses of the external DNS servers which are no longer online.
If i do a ipconfig /flushdns on the client, and ipconfig /renew the results shown in ipconfig /all show the correct two internal DNS servers, after about 3-4 minutes, if i do another ipconfig /all, the PC's DNS servers have changed back to the old incorrect ones.
The laptop has had a new OS installed and the problem persists,
I have also set the 006 DNS options directly against the reserved ip address.
I have searched the registry of the server for the old dns ip address and its not present.
I have flushed the dns cache on the DHCP server.