As root type this;
Code:
gedit /etc/resolv.conf
and hit enter,then add this line;
nameserver (ip addres of your DNS server) where ip address is the address of your DNS server.If you have DHCP then you can put gateway address there.Save the file and reboot.
Or when you're in the etc/resolv.conf directory on the command line do;
Code:
nameserver (ip address) add