[dns-operations] edns-client-subnet capable authorities?

[David C Lawrence]

Mark Andrews writes:
> In making a decision about whether to probe or white list you may want
> to look at https://ednscomp.isc.org/compliance/summary.html which has
> graphs of the failure modes for unknown EDNS options.

Good point, Mark.  I will point out that our own recursive team didn't
want to have to deal with whitelists either (which is perfectly
rational) and just thought they'd use it everywhere.

Personally I didn't think this was great philosophically, but
independent of my feelings on the matter it turned out to be terrible
in real world operational terms.

At least a couple of the Alexa Top 1000 domains would just black-hole
queries that had ECS.  No reply, timeout.  Of course a resolver would
have a hard time automatically interpreting the cause of the timeout
and would have to do extra work to id the problem as likely because of
the presence of the option.