help.dnsp.co

Ask the server what it can do.

What it does

Every option this site documents is also listed by the server itself. Ask help.dnsp.co for its TXT record and you get the current list, one name per option, generated by the running server rather than written down here.

That makes it the authoritative answer to what is available. This site can fall behind; the server cannot. If you find something in this list that is not documented here, the server is ahead of the documentation, and the option still works.

It is also a quiet interference check. The list is long and specific, so an answer that comes back short, empty or altered says something is rewriting responses between you and us.

Reading the answer

your own public IP

You are talking to us directly and nothing re-originated the query.

a different public IP

A resolver or proxy is asking on your behalf, which is normal when you did not use @dnsp.co.

an address in your own network

Something inside your network is terminating DNS and forwarding it itself.

a new address each try

You are behind a resolver fleet. Repeat a few times before concluding anything.

Notes

The answer is a set of names rather than prose, so it is easy to script against.
Asked over UDP the list may be truncated. Add +tcp to be sure you have all of it.