sudo cp /etc/resolv.conf /etc/resolv.conf.auto
sudo gedit /etc/dhcp3/dhclient.conf
Look for the below line, which will be commented, and match this setting. add your dns addresses
# append the following line to the document
prepend domain-name-servers XXX.XXX.XXX.XXX,XXX.XXX.XXX.XXX;
Once your entry matches this you will want to save the file and restart networking using a command such as the one below.
sudo ifdown eth0 && sudo ifup eth0