Looks like com.apple.discoveryd.plist has replaced com.apple.mDNSResponder.plist
I issues the following commands and my iMessages bonjour started to work again. This is under Public Beta 3.0
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.discoveryd.plist sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.discoveryd.plist
Looks like com.apple.discoveryd.plist has replaced com.apple.mDNSResponder.plist
I issues the following commands and my iMessages bonjour started to work again. This is under Public Beta 3.0
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.discoveryd.plist
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.discoveryd.plist