#!/bin/bash
DNS_SERVER="1.1.1.1"
networksetup -getdnsservers Wi-Fi | grep -q "$DNS_SERVER"
if [ $? != 0 ]; then
   networksetup -setdnsservers Wi-Fi "$DNS_SERVER"
   echo "Added 3rd party DNS $DNS_SERVER"
else
   networksetup -setdnsservers Wi-Fi Empty
   echo "Removed 3rd party DNS"
fi