NEGATIVE_CACHE_LIKELY

warning

This name does not exist yet and the absence may be cached for a while. Wait before re-checking.

Working today, and one change away from not working.

How we know

negcache-low.test
SOA MINIMUM 3600 with a 300s SOA TTL. RFC 2308 says the negative TTL is the smaller of the two; taking MINIMUM alone is the classic bug.
negcache-high.test
An address and no TXT, so a TXT query is NODATA rather than NXDOMAIN and the answer carries the SOA that says how long that will be remembered. An hour is the interval that generates support tickets: long enough to be disbelieved after a correct edit, short enough that nobody suspects caching. negcache-low.test at 60 seconds is the counterpart that must produce nothing.