Quad9 is a free security solution that uses DNS to protect your systems against the most common cyber threats.
You can setup Quad9 on Mac OS in four easy steps.
Go to System Preferences and select Network Settings.
Click Advanced and select DNS.
Click the ‘+’ sign and add 220.127.116.11 to the top of the list. Optional: You can add 18.104.22.168 as the second entry in the list.
Click Ok and then Apply.