How to configure your DNS settings on Mac

Short: System Preference > Network > Airport (WiFi) or Ethernet (LAN) > Advanced.. > DNS > under DNS Servers click the + button > Add 208.67.222.222 and 208.67.220.220 (or any other IPs from the list below) > OK
When you're on your desktop, click the Mac Apple, then click on "System Preferences". The System Preferences window will appear. Click on "Network" here.
Now you'll see the Network center. Select your ethernet adapter here on the left, then click on "Advanced..."
Click on the "DNS"-tab. Now you can add DNS servers by clicking on the "+" in the bottom left.
Add the desired DNS servers: OpenDNS: 208.67.222.222 + 208.67.220.220 ComodoDNS: 156.154.70.22 + 156.154.71.22 GoogleDNS: 8.8.4.4 + 8.8.8.8 UltraDNS: 156.154.70.1 + 156.154.71.1 NortonDNS: 198.153.192.1 + 198.153.194.1 Once finished, click on "OK" at the bottom right of this window.
Back in the network center, you'll see that the newly added DNS servers now appear right next to "DNS Server:" - so it's done now. Click on "Apply" at the bottom right to save your changes. You've successfully changed your DNS settings.