DNS servers should not be used as "internet connectivity tests" by pinging them. They are not maintained as ICMP test servers, and that is not their purpose. While many do not block ICMP packets, there are typically rate limiting systems in place, and other reasons why they would not respond to ping requests.
Pinging DNS servers is a shitty inconclusive test for internet connectivity, or SLA measurements etc etc.
Pinging DNS servers is a shitty inconclusive test for internet connectivity, or SLA measurements etc etc.