Re: [DNSOP] draft-ietf-dnsop-extended-error status

On Mon, Sep 30, 2019 at 7:54 AM Tony Finch <dot@dotat.at> wrote:
>
> Wes Hardaker <wjhns1@hardakers.net> wrote:
> >
> > 2) One outstanding topic of discussion that I think we need to decide to
> > handle or table till a future document: how do we handle forwarding,
> > chained resolvers, and caching.
>
> Difficult. In general there will be multiple upstream servers, even in
> the simplest case of a stub talking to a recursive server talking directly
> to authoritative servers. So there can be an arbitrary combination of
> upstream errors, and they might not relate directly to the QNAME, (e.g.
> problems with a parent zone, problems chasing down nameserver addresses).
>

RFC 6891 - Extension Mechanisms for DNS (EDNS(0)) speaketh thusly:

"EDNS is a hop-by-hop extension to DNS. This means the use of EDNS is
negotiated between each pair of hosts in a DNS resolution process,
for instance, the stub resolver communicating with the recursive
resolver or the recursive resolver communicating with an
authoritative server."

and also sayeth:
"OPT RRs MUST NOT be cached, forwarded, or stored in or loaded from
master files."

I *think* that this covers the issue for many cases; EDE is not
intended to be a silver bullet, more something which provides useful
information for troubleshooting / debugging.
We would not (and cannot :-)) preclude other work from further
defining this, but I think that it's beyond the scope of this document
/ we will better be able to understand things once we've had some
deployment experience.

Thank you,
W

> Perhaps if the upstream problems are consistent with each other, the
> resolver can return a single extended error code to its client; otherwise
> fall back to a "multiple errors" catch-all?
>
> Tony.
> --
> f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
> Malin: East backing northeast 5 to 7. Moderate or rough. Showers. Good.
>
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-- 
I don't think the execution is relevant when it was obviously a bad
idea in the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair
of pants.
   ---maf