I did a clean reinstall of OS X 10.6.8 and was immediately stymied by being unable to connect to the Internet.

After my head-scratching degenerated to angst, though, I had a brainstorm, went looking, and found that importing my network settings had left me with the DNSCrypt DNS server numbers in place, and they were, of course, useless before DNSC was reinstalled.

I hope nobody gets stuck having to reinstall, but if you do, keep this in mind, and either make a note of the Open DNS server numbers or reinstall DNSC forthwith.

Several times I've had to go in and just outright delete interfaces (and either let them auto recreate or make them again explicitly) to fix misbehaving adapters.

This is an especially common issue with airport, much moreso than ethernet.