Problem joining 10.10.3 (Yosemite) to Active Directory.

Ran into this myself. 10.10.1+ made some changes to the way the .local name is handled. Essentially bonjour is attempting to handle the resolution of .local instead of DNS. The solution is to tell the discoveryutil to return to the old way of handling it:

sudo discoveryutil mdnsactivedirectory yes

This however will only work until the next restart, you will have to create a LaunchDaemon to force it to apply on ever reboot.

Something like:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.company.discoverydfix.local</string>
    <key>ProgramArguments</key>
    <array>
        <string>/usr/sbin/discoveryutil</string>
        <string>activedirectory</string>
        <string>yes</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>ServiceDescription</key>
    <string>.local fix</string>
</dict>
</plist>

This actually may have been resolved in 10.10.4 (changed back to the way it worked before). I haven't checked since I already have this setup on all machines now and it's working since application.

Thank you, I will give this a try!