<name>.relay.dnsp.co
The only test that performs a real lookup.
What it does
Put a real name in front of relay.dnsp.co and we strip the suffix, ask an ordinary resolver ourselves, and hand back what it said. It is the honest answer to compare all the synthetic ones against.
Example
$ dig @dnsp.co google.com.relay.dnsp.co +short
142.250.72.206
Reading the answer
the same address your resolver gives
Your view of that name matches ours.
a different address
Your resolver disagrees with the public view, whether through filtering or geography.
no answer
The name does not resolve for us either.
Notes
- Geographic load balancing makes small differences normal for large sites.
- Use it as the baseline when a specific name looks wrong.