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

Jimmy Hess mysidia at gmail.com
Mon Jul 8 15:04:31 UTC 2019

On Mon, Jul 8, 2019 at 8:41 AM Tony Finch <dot at dotat.at> wrote:
> > I thought SHOULD was for cases where there might be reasons outside the
> > spec for not doing the thing, whereas I am talking about how to

The ramifications for a standard are wherever it says SHOULD:  other entities
implementing this besides you may disregard anything that says SHOULD,
and their implementation is still fully compliant -- a consequence of
the application of the
robustness principle from STD 3  (RFC1123)  is  any implementor must be
prepared to assume other sites implementing might disregard any SHOULD
statement,  since they are not required

See [RFC1123] 1.2.2
> A corollary of this is "watch out for misbehaving hosts"; host software should
> be prepared, not just to survive other misbehaving hosts, but also to cooperate
> to limit the amount of disruption such hosts can cause

And  Meaning of the SHOULD terms is shown by RFC 2119.

"3. SHOULD This word, or the adjective "RECOMMENDED", mean that there
may exist valid reasons in particular circumstances to ignore a
particular item, but the full implications must be understood and
carefully weighed before choosing a different course.""


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