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 BIND 9.12 and 9.18 suggests that ANSWER:0 is not cached at all, and that each recursive request received results in a query from the caching resolver to the authoritatives (the authoritative is not running BIND). I'd appreciate a pointer to an RFC which specifically discusses this. I'd also appreciate (from someone who's read the code) a statement of what the intended semantics are, before I go read the code myself. Presuming that the ANSWER:0 response is authoritative, is there any expectation regarding content in the ADDITIONAL or AUTHORITATIVE sections which affects this behavior? NS? SOA? Thanks in advance... -- Fred Morris -- Visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information. bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
