How Do You Interview A Network Engineer?

vrmlguy asks: "Back in July, we learned how to interview programers, and in August we learned how to interview sysadmins. Obviously, we still need to hire some network engineers, but what questions should we ask? The previous articles had a couple of generic gems which I intend to put to good use, but the only position-specific question that I can come up with is "Please explain the differences between RIP and OSPF." Any other ideas for a guy whose idea of using a sniffer is to fire up tcpdump?"