x.count.dnsp.co

As many answers as you ask for, up to 255.

What it does

Put a number in front of count.dnsp.co and you get that many addresses back. Raising the count until answers stop arriving finds the practical size ceiling of the path between you and us.

Example

$ dig +tcp @dnsp.co 40.count.dnsp.co +short

0.0.0.1

0.0.0.2

;; 38 more

Reading the answer

exactly the number you asked for

Nothing truncated the response at that size.

fewer records

Something along the way cut the answer short.

a truncated flag

The answer did not fit and a retry over TCP is expected.

Notes

Only available over TCP. UDP size limits make the result meaningless.
255 is the hard maximum, though DNS message limits usually bite first.