Comment 30 for bug 1670959

@ Michael Roth (mdroth)

On zesty and later /etc/resolv.conf must not list "nameserver 127.0.0.1" this seems to be broken configuration state.
I am concerned how you got into such a state. Is your network managed by ifupdown with /etc/network/interfaces or NetworkManager? do you have resolvconf installed? What is the output of $ NetworkManager --print-config | grep dns ?

@tomposmiko
$ systemctl disable systemd-resolved
$ systemctl stop systemd-resolved
$ systemctl mask systemd-resolved
$ apt remove --purge libnss-resolve

Should do it. Then you should still have resolvconf & ifupdown installed, or resolvconf+dnsmasq+NetworkManager installed. Or without resolvconf manage /etc/resolv.conf by hand.
Note such system configurations may not be fully supported, but should be operational for simplistic networking setups.