Comment 8 for bug 1673860

Confirmed this fix in yakkety. Behavior with systemd 231-9ubuntu3:

# journalctl -o short-precise -u systemd-resolved -u network-online.target --no-pager
-- Logs begin at Thu 2017-04-20 23:50:20 UTC, end at Fri 2017-04-21 03:22:45 UTC
Apr 20 23:51:06.897218 ubuntu systemd[1]: Starting Network Name Resolution...
Apr 20 23:51:06.899220 ubuntu systemd[1]: Reached target Network is Online.
Apr 20 23:51:12.471807 ubuntu systemd-resolved[1116]: Positive Trust Anchors:
[...]
Apr 20 23:51:19.152992 ubuntu systemd[1]: Started Network Name Resolution.

Behavior with systemd 231-9ubuntu4 (with an extra ExecStartPre=/bin/sleep 10 in systemd-resolved.service for good measure):

# journalctl -o short-precise -u systemd-resolved -u network-online.target --no-pager
-- Logs begin at Fri 2017-04-21 03:27:20 UTC, end at Fri 2017-04-21 03:27:47 UTC. --
Apr 21 03:27:26.077418 ubuntu systemd[1]: Starting Network Name Resolution...
Apr 21 03:27:36.134810 ubuntu systemd-resolved[1119]: Positive Trust Anchors:
[...]
Apr 21 03:27:36.174373 ubuntu systemd[1]: Started Network Name Resolution.
Apr 21 03:27:38.955658 ubuntu systemd[1]: Reached target Network is Online.