Hi folks, Paul Vixie, Ralph Dolmans, and I have submitted this I-D for consideration:
https://tools.ietf.org/html/draft-huque-dnsop-ns-revalidation-01 I mentioned it on the dns-operati...@dns-oarc.net mailing list last week, where the topic came up in another thread, and there has already been some lively discussion about it there. So we recommend reading the thread there: https://lists.dns-oarc.net/pipermail/dns-operations/2020-April/020041.html There is a range of different behaviors in resolver implementations in this respect today, and it would be good if we could agree on more commonality. The main recommendations in the draft are to: (1) deterministically prefer the authoritative child NS set over the non-authoritative, unsigned, delegating NS set in the parent, (2) revalidate the parent delegation at the expiration of the parent NS set TTL, to promptly detect when the parent has re-delegated the zone elsewhere (or removed the delegation). These are not new ideas of course. They have been proposed in Vixie et. al.'s resimprove draft from 2010, and Wouter Wijngaard's resolver mitigations draft from 2009. The Unbound resolver already mostly implements this with the 'harden-referral-path' configuration option. Comments/discussion welcome. Shumon, Paul, and Ralph.
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