Some DNS tests, DNS alternates

Was curious about some DNS entropy and other DNS related things and came across some tools to test DNS.

This one will test with random long sub-domain names. Apparently some routers will crash.

https://www.grc.com/dns/crashtest.htm

This one is customizalbe test and will run for a while.

https://www.grc.com/dns/customtest.htm

This is some general info about publically available DNS servers.

https://www.grc.com/dns/alternatives.htm

Some offer parental controls, some hijack nxdomain responses, etc.
Some just give honest answers.