Seriously? Somehow the routing table had an extra route - 66 - added. This prevented all traffic from/to hosts whose IP addresses began with 66., but I have no idea what added the route or why it was added. It apparently happened the other day.
What's more, I couldn't delete the route no matter what I tried, so I ended up having to reboot the server to get rid of it.
This is the first time that I've had to use the DRAC card to avoid having to drive to Bedford to fix a problem, so it was very nice to have that functionality.
