Modify the file/etc/resolvconf/resolv.conf.d/base(This file is empty by default), add the following content:

nameserver 8.8.8.8
nameserver 8.8.4.4

:wq save and exit

Execute update:

resolvconf -u

Via/etc/resolv.confView DNS settings:

You can see there are more:

nameserver 8.8.8.8
nameserver  8.8.4.4