These steps are based on the OSX Yosemite support article at: http://support.apple.com/kb/PH18499
1. Go to System Preferences
4. Select the DNS tab and add 184.108.40.206 and 220.127.116.11 to the list of DNS servers. Click OK
If there are any greyed out IP numbers they can be ignored.
5. Cache Flushing
At the point, we highly suggest that you flush your DNS resolver cache and web browser caches to ensure that your new DNS configuration settings take immediate effect.