I recently upgraded to snow leopard and noticed some DNS weirdness. I couldn’t ssh to hosts defined in my local DNS, it wouldn’t resolve, but I could resolve them with the host command.

Turns out Snow Leopard made quite a few changes to the resolver, it no longer uses /etc/resolv.conf but mDNSResponder, at least for apple supplied applications.

Unlike every other OS I’ve come across, including Leopard, Snow Leopard doesn’t use the order of DNS servers as first listed, first used. It swaps which DNS it’s going to use around, seemingly at random times. Some sort of load balancing miss feature?

I had two DNS servers configured, the first one, my local DNS server, the second, my ADSLs DNS server as a backup. The simple fix is to only have one DNS server configured.

There’s more information here Snow Leopard Resolver.

I’m not unhappy with OS X, but lately I’ve been pining to return to a linux based laptop. I think this will be my first and last Mac.