Some of our very hard working colleagues and clients noticed that our web server was unavailable between about 10:30pm on February 20 until just about 12:15am on February 21. The root cause of the problem was that the network switch serving our database server failed, and that causes significant problems for the web server.
After fielding the page and driving into the office, the on-call member of my team discovered that the web server was indeed up and running, but not answering any connections from the network. She then diagnosed the problem, discovering that the network interface on the server was OK, but the network switch was not. Some quick work finding a long cable and a free network port elsewhere in the machine room solved the problem.
Our apologies for the inconvenience this caused.