Fred,
Most of the details are in RFC 2308 (Negative Caching of DNS Queries).
On Sat, Apr 6, 2024 at 9:16 AM Fred Morris wrote:
> So the answer is in two parts.
>
> 1) An SOA record is required in the AUTHORITY section. The TTL on the
> negative answer is established by the TTL on this record.
>
So the answer is in two parts.
1) An SOA record is required in the AUTHORITY section. The TTL on the
negative answer is established by the TTL on this record.
2) "TTL on this record" means the literal TTL applied to the SOA record,
not e.g. the minimum TTL specified within the SOA record.
-
When people think of "negative response caching" I suspect they're
thinking of NXDOMAIN, but there is another negative response: ANSWER:0.
To some extent this is indistiguishable from a referral, and I'm not
sure that caching of (upward) referrals is a sensible concept on its own.
Testing with BIN
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