mDNSResponder missing I am on Yosemite since today and am trying to connect to network printers, but System Preferences doesn't show any. The printers use Bonjour and I read that the associated process is mDNSresponder. Checking Activity Monitor I see it is not running. Googling how to manually restart it reveals tips such as these.

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist


However, the .plist file does not exist, neither does /usr/sbin/mDNSResponder.

The thing is that the printer problem existed even before I upgraded from 10.7.5 to 10.10, so I cannot judge whether this is a Yosemite issue or not, or wether the mDNSResponder stuff is even the source. I also don't know if I had the files before (although at some point I must have).

How do I enable Bonjour on Yosemite?
mDNSResponder was replaced by DiscoveryUtil in Yosemite. So Bonjour is still enabled. According to this Apple-kb article you might have to download updated printer drivers from Apple or the original manufacturer or re-add your printer with a different set up.
If you still have problems discovering your printer an Apple-discussion-thread might help:  unblock discoveryd in the firewall preferences and an immediate reboot...