Weird... I thought they had that whupped! They adjusted the sequence of DNS-related addresses in the nameserver and it's been working ok here when I've been on, but obviously still buggered. I repeat for the general audience, use the Tortuga link if the MLU one doesn't work:
http://tortuga.dnsrouter.com/~mlu/forums/
This is the router address sans DNS. If it doesn't work then they're rebooting the server, either that or it's under attack. I'm going to request a change of server to see if that works - I'll try to give you notice, but if you encounter extended outage, that may be the reason why.
One way or another we'll sort this out!!