loopback.dnsp.co
A freshness check you can run with ping.
What it does
loopback.dnsp.co returns an alias that carries the time the answer was generated and points at your own machine, ::1 or 127.0.0.1. Because ping prints the alias it resolved, you can judge DNS freshness on a machine with no DNS tools installed at all.
Example
$ ping loopback.dnsp.co
Pinging Wed_16_Sep_2026_02_28_20_423417.loop.dnsp.co [::1] with 32 bytes of data:
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
;; the alias carries the time the answer was generated
Reading the answer
an alias matching the current time
Fresh resolution.
a stale alias
The answer came from a cache, and the timestamp is when it was stored.
an address that is not your loopback
The alias was rewritten, which is worth following up with the basic test.
Notes
- The alias looks like Wed_16_Sep_2026_02_28_20_423417.loop.dnsp.co: the date and time we generated it, down to fractions of a second.
- Safe to ping: it always resolves to your own machine, ::1 or 127.0.0.1.
- The timestamp is printed by ping itself, so you need no DNS tools at all.
- Handy on Windows, where nslookup output is awkward to read.