If you are running a local DNS server like named/bind and don't want to use the ISPsupplied DNS servers that are announced via a DHCP request (using dhclient) then the solution is simple.
The reason should be obvious, but normally running your own DNS server will provide a more reliable, and fast DNS response and you won't have to worry about filtering as much (unless your upstream filters or proxies outgoing DNS requests).
Edit /etc/dhcp/dhclient.conf........
First we need to create dhclient.conf if it doesn't exist or edit it:
vi /etc/dhclient/dhclient.conf
#add this line at the top add the IPs as commas they will be the highest priority nameservers and whatever your ISP gives you will be used after these one (good for DNS backup)
prepend domain-name-servers 127.0.0.1,10.10.25.8;
After you restart your network or run dhclient again you should see the contents of........