TL;DR: sudo discoveryutil mdnsactivedirectory yes
After upgrading to Mac OS X 10.10 Yosemite, I found myself unable to access any hosts with a domain name ending in .local
I could resolve the hostname with DNS tools like dig and nslookup, but other tools, namely ssh and ping, refused to do so.
As it turns out, Yosemite (and apparently also iOS 8) changed the way of resolving host names ending in .local to conform to the relatively new RFC 6762.
After much digging I found a fix in the Apple support forums:
sudo discoveryutil mdnsactivedirectory yes
Note that this fix only lasts until the next reboot.