Mac OS X v10.6: Disabling mDNSResponder will disable DNS
Summary
Mac OS X v10.6 uses the mDNSResponder process for unicast DNS (Domain Name System) functions, as well as Bonjour functions. Disabling the mDNSResponder process will also disable unicast DNS resolution, and without unicast DNS resolution, Mac OS X v10.6 cannot resolve hostnames such as www.apple.com.
In some network environments, administrators may prefer that Mac OS X v10.6 not transmit Bonjour service advertisements. You can use this advanced article if you are a network administrator who needs to disable Bonjour advertising service without disabling Bonjour queries and DNS.
Products Affected
Bonjour, Mac OS X 10.6, Bonjour
Important: Follow these steps carefully. A malformed or problematic mDNSResponder.plist file may prevent your Mac from starting up. As a precaution, perform a full backup of your system with Time Machine.
- Make a back up copy of the mDNSResponder.plist file as a precaution.
- Open the mDNSResponder.plist file in Terminal using your preferred text editor. Here is a sample command:
sudo nano "/System/Library/LaunchDaemons/com.apple.mDNSResponder.plist"
- Add "<string>-NoMulticastAdvertisements</string>" to the array in the "ProgramArguments" section.
In other words:
<key>ProgramArguments</key> becomes...
<array>
<string>/usr/sbin/mDNSResponder</string>
<string>-launchd</string>
</array>
<key>ProgramArguments</key>
<array>
<string>/usr/sbin/mDNSResponder</string>
<string>-launchd</string>
<string>-NoMulticastAdvertisements</string>
</array>
- Save the file.
Important: If you edited the file using emacs, you must remove the emacs backup file (the file with a tilde at the end of the name, "/System/Library/LaunchDaemons/com.apple.mDNSResponder.plist~") or your Mac will not start up.
- Restart your Mac.
Additional Information
Prior to Mac OS X v10.6, the only way for a network administrator to disable Bonjour advertising of services was to completely disable the mDNSResponder process, which also disabled Bonjour discovery of services (such as discovering network printers).
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