MATE 17.10 name resolution - how is it done?

I have two instances of 17.10. One of them has a problem with name resolution. For example:

user@ub1710bug:~$ ping -c1 ubuntu.com
ping: ubuntu.com: Temporary failure in name resolution

The IP address for ubuntu.com is 91.189.94.40

user@ub1710bug:~$ ping -c1 91.189.94.40
PING 91.189.94.40 (91.189.94.40) 56(84) bytes of data.
64 bytes from 91.189.94.40: icmp_seq=1 ttl=52 time=161 ms

On the broken machine /etc/resolv.conf does not exist. How is this generated?

Output of systemctl status systemd-resolved is identical for both machines.
And curiously, both machines have this response :

systemd-resolve status
status: resolve call failed: All attempts to contact name servers or networks failed