Screen Sharing trying to connect to Apple Kerberos server?

I'm using a MacBook Pro running 10.10.1. When I connect to other Macs via Screen Sharing, it now takes a very long time to connect (a lot longer than when I was on 10.9).

The culprit seems to be this:

1/7/15 11:00:08.606 AM NetAuthSysAgent[10688]: NAHSelectionAcquireCredential The operation couldn’t be completed. (com.apple.NetworkAuthenticationHelper error -1765328228 - acquire_kerberos failed username@WELLKNOWN:COM.APPLE.LKDC: -1765328228 - unable to reach any KDC in realm WELLKNOWN:COM.APPLE.LKDC, tried 1 KDC)

So it's trying to look me up on Apple's Kerberos server, and timing out. Any way to stop Yosemite from doing this? Or is there another solution?