If you are using ubuntu 14.04, you may find you can not setting dns on your /etc/resolv.conf
This is because ubuntu using resolvconf to manage the dns setting, every times system boot, resolvconf will regenerate resolv.conf file.
But there always have way to do this.
vim /etc/resolvconf/resolv.conf.d/head
put your nameserver list in
nameserver 8.8.8.8nameserver 8.8.4.4
then run
resolvconf -u
this command tell resolvconf to regenerate the resolve file
enjoy it.
