To test for speed, GRC offers the free DNS Benchmark utility (the pro version offers more features). Run the f ...

You can do various things if the DNS server isn’t responding. You can configure the DNS manually, and use a different DNS address, maybe switch to Google Public DNS and see if that helps.

In addition to the DNS server for a domain you control, you’ll also need ssh access to your server set up to use a certificate and not a password. You probably need root access, too, although I ...