[dns-operations] Questions on DNS Flag day 2020 proposal

Mark Delany b9w at charlie.emu.st
Tue Jun 18 02:11:15 UTC 2019

> STD13 doesn't say glue as optional and not being able to fit glue
> into a referral response should result in TC=1 being set.

Do you mean for auths only or intermediaries as well?

I'm thinking of caches and proxies which accept a TC=0 answer from their
upstream but find they have to truncate this answer to suit their downstream

Do intermediaries reliably know which RRSets are "required" (to use rfc2181
parlance) or should they take a safe/simplistic approach and arbitrarily set
TC=1 on all downstream truncation? That would certainly cover your use-case.

A brief examination suggests that intermediaries are all over the shop in this
regard but obviously mostly "work" so long as the Answer section is non-empty or
TC is set. In spite of this (or perhaps because of this) guidance for all
components would be helpful.


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