You don't need #OpenDNS , you have your own dns server on #Ubuntu !ubuntu

Install isc bind server

sudo apt-get install bind9

test if the dns query works

$ dig reea.net @127.0.0.1

make it default resolver for your system

sudo pico /etc/resolv.conf

or open it with any editor

sudo kate /etc/resolv.conf
add this entry
nameserver 127.0.0.1

delete all other nameservers or comment them if you want

and that is all (tested on ubuntu karmic and intrepid)