[DNSOP] Benjamin Kaduk's Discuss on draft-ietf-dnsop-kskroll-sentinel-15: (with DISCUSS and COMMENT)

Benjamin Kaduk <kaduk@mit.edu> Wed, 26 September 2018 15:16 UTC

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From: Benjamin Kaduk <kaduk@mit.edu>
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Date: Wed, 26 Sep 2018 08:16:24 -0700
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Subject: [DNSOP] Benjamin Kaduk's Discuss on draft-ietf-dnsop-kskroll-sentinel-15: (with DISCUSS and COMMENT)
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Benjamin Kaduk has entered the following ballot position for
draft-ietf-dnsop-kskroll-sentinel-15: Discuss

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Thanks for preparing this document and mechanism; it is good to have more
data about the expected impact of the root KSK roll.  That said, I have two
Discuss-worthy points, albeit both fairly minor.

The first one may just be something that I missed, but does this document
actually say anywhere that there needs to be a real zone with real
configured A and/or AAAA records for the query names used for these tests?
The Appendix sort-of-mentions it, but I feel like there needs to be a
mention in the main body text.

The other point basically is a procedural one, in that we are in effect
claiming a couple of leaf name prefixes in all domains to exhibit "weird
and surprising behavior" (that is, for parties unaware of this
specification).  We generally try to avoid this sort of namespace
squatting, preferring (e.g.) /.well-known for HTTP requests, various
underscore-prefixed tricks for the DNS, etc.  I see in the changelog that
initial attempts did use an underscore prefix but ran into implementation
difficulty, and acknowledge that using a "magic" name is much easier to get
deployed than (e.g.) a new RR type.  But I do not want the IESG to
implicitly approve a namespace claim like this; it's better to be explicit
about it if this is the best way to go.


Other than my Discuss points, I just have a number of essentially editorial


                                This document specifies a mechanism that
   will allow an end user and third parties to determine the trusted key
   state for the root key of the resolvers that handle that user's DNS
   queries.  [...]

This wording feels confusing to me; I think what it's trying to say is "the
root key(s) that are in use by the resolver" but am having a hard time
grouping these words to achieve that meaning.  (Is "trust" really necessary
to mention, here?)

Section 1

               RRSIG RRs contain a Key Tag field whose value is equal to
   the Key Tag of the DNSKEY RR that was used to generate the
   corresponding signature.

nit: Is the RR used to generate the signature, or just the key?

   o  Users may wish to ascertain whether their DNS resolution
      environment resolvers is ready for an upcoming root KSK rollover.

nit: I think there's a singular/plural mismatch or similar here, maybe
"environment's resolver"?

   o  Researchers want to perform Internet-wide studies about the
      proportion of users who will be negatively impacted an upcoming
      root KSK rollover.

nit: "by an upcoming"

   If a browser or operating system is configured with multiple
   resolvers, and those resolvers have different properties (for
   example, one performs DNSSEC validation and one does not), the
   sentinel test described in this document can still be used, but it

nit: this usage of "but" feels a bit misplaced to me, as the thing being
warned about is more that the test may produce indeterminate or
inconsistent results.  Or perhaps that the assumptions it makes may not
necessarily hold in the specific environments being described (i.e., "these

   makes a number of assumptions about DNS resolution behaviour that may
   not necessarily hold in all environments.  If these assumptions do
   not hold (such as, for example, requiring the stub resolver to query
   the next recursive resolver in the locally configured set upon
   receipt of a SERVFAIL response code) then this test may produce
   indeterminate or inconsistent results.  In some cases where these
   assumptions do not hold, repeating the same test query set may
   generate different results.

Section 1.1

Please use the RFC 8174 boilerplate.

Section 3

I'll note without further comment that we had a long thread on ietf@
relevant to the term "slave resolver".

Section 3.1

   If the resolver is non-validating, and it has a single forwarder,
   then the resolver will presumably mirror the capabilities of the
   forwarder target resolver.

Perhaps this is just me misreading the previous paragraph's introduction to
what is clearly a more widely known term of art, but in "has a single
forwarder" is the thing of which there is only one the "one or more other
resolvers" that the "forwarder" is relaying queries to?  It's just weird
for the word "forwarder" mean a different protocol participant when used as
a noun vs. adjective.  Or perhaps this is meant to be possessive; the
"forwarder's target resolver"?

As noted in the directorate review, "use the CD bit" needs disambiguation.

Section 4

nit: missing trailing 'r' in the section title

Section 4.3

Maybe call out that these are the same general categories of query as in
Section 3 but the key tag used is different for some queries?

It's also a bit weird to use new notation for this section as opposed to
consistent notation between the different types of test.