Here's how to squash this bug yourself, if you can't afford to wait on Apple.



From ArsTechnica:

For 12 years, the mDNSResponder service managed a surprisingly large part of our Mac's networking, and it managed this task well. But as of OS X 10.10, the mDNSResponder has been replaced with discoveryd, which does the same thing. Mostly. Here are some strange networking problems we've observed since installing 10.10:

Random failures to resolve DNS names. This is rare, but every once in a while, Safari stops loading any and all websites. Turns out that the OS X DNS resolver has stopped working. (Command line tools such as nslookup, host, or dig still work because those use their own DNS lookup code.)

  Why DNS in OS X 10.10 is broken, and what you can do to fix it