Apple released a whopper of an update for Snow Leopard today. There’s lots of in-depth coverage in various places.
All I know is that this update is supposed to fix this pain in the ass DNS bug. The short story is that Apple pushed DNS resolution facilities completely into the mDNSResponder daemon. Problem was that if a DNS server would occasionally time out, mDNSResponder would adjust the order in which it would solicit DNS servers. This can cause problems where you use a local DNS server to resolve machines on your LAN, then an ISP or public DNS server backs up your local server. Eventually errors like this would pop-up:
ssh: Could not resolve hostname nightcrawler: nodename nor servname provided, or not known
The bug wasn’t a heinous show stopper, renewing your DHCP lease seemed to fix it, but it was still a major irritant.
There’s allegedly a fix to support this DNS situation according to Apple’s update notes. Hopefully if anyone else is still suffering from this pest, this post can point them in the right direction.