mDNSResponder Constantly Doing "Something"

I noticed my mDNSResponder connecting constantly to opendns (didn't always happen but when it did it was constant). Found the links below. It basically requires a bit of under-the-hood tweaking.

1. Make a back up copy of the mDNSResponder.plist file as a precaution.
2. 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" 
   

3. Add "<string>-NoMulticastAdvertisements</string>" to the array in the "ProgramArguments" section.
   
   In other words:
   

     <key>ProgramArguments</key>
           <array>
               <string>/usr/sbin/mDNSResponder</string>
               <string>-launchd</string>
           </array>    
   

   becomes...
   

           <key>ProgramArguments</key>
           <array>
               <string>/usr/sbin/mDNSResponder</string>
               <string>-launchd</string>
          <string>-NoMulticastAdvertisements</string>
     </array>
   

4. 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.
   
5. Restart your Mac.

****

UPDATE 12 June 2010: The problem, as it turns out, was listing my OpenDNS servers in both my Airport Extreme (for the entire home network) and my Mac Pro. As soon as I deleted the OpenDNS servers from Network Preferences on my Mac Pro, everything returned to normal...no more constant outgoing connections. The above method worked too, but it was at the cost of losing Bonjour connectivity on my home network (not acceptable).

[From Snow Leopard disabling mDNSResponder/Bonjour drops internet - Mac Forums]

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.

[From Mac OS X v10.6: Disabling mDNSResponder will disable DNS]

OSX's Firewall: ipfw

Don't waste your money on other firewall products. Apple comes with two great ones built right in. One can be found in System Preferences->Security->Firewall. The other is hidden and a bit more powerful. Just grab one (or both) of these free utilities to ease your ipfw configuration (which can be a little tedious via the command line), and you'll be safer in your online activities. These firewall offerings basically control what data is allowed into your computer, so if you ever have trouble doing something online, check your firewall settings first.

You might want to add Little Snitch too (for outgoing connections), and if you connect with a router, keep in mind that you're already behind a hardware firewall. You need a software firewall for when you're at Starbucks or some such place, using a wireless hotspot.

Macworld | Mac Gems | NoobProof 1.1 and WaterRoof 2.0:

Mac OS X’s built-in firewall—an implementation of the Unix ipfw program—works well, but Apple offers very few options for configuration. Hanynet’s NoobProof 1.1 and WaterRoof 2.0 are utilities that provide just such customization.

Safari 3.1.1. - "Error while printing"

Here's a weird one. Under one account on my Powerbook, I suddenly can no longer print from Safari (3.1.1.) via Bonjour (i.e., a shared printer on another Mac). Other applications work fine, and other accounts can print from Safari.

Console consistently looked like this:

2008-05-11 10:22:09.602 Safari[1609] PMSessionValidatePrintSettings failed (error code = -50)
2008-05-11 10:22:09.672 Safari[1609] PMSessionEndDocumentNoDialog failed (error code = -30871)
2008-05-11 10:22:11.243 Safari[1609] Failed to end PMPrintContext

Here are the solutions I tried that were ineffective:

• Repaired permissions
• Deleted caches for all applications
• Updated printer drivers (just in case, though no other apps were affected)
• Deleted user safari prefs
• Deleted user print prefs
• Ran Printer Setup Repair
• Resetting Printing System via Printer Setup Utility on both host and client machines

The culprit?

Little Snitch...it had been accidentally set to block Safari connections.