This morning I installed a lot of updates on my machine
at work which is setup with "network", NOT NetworkManager.
I rebooted, and had no network. DHCP not giving me an IP,
ypbind not talking, etc.
After much flailing around, I found the socket
systemd-networkd.socket
enabled (I have no idea if it has always been enabled),
so I disabled it, rebooted again, and all networking
was once again functioning perfectly.
Just thought someone else might run into this and could
use my solution.