An EDNS(0) option to negotiate Leases on DNS Updates
draft-ietf-dnssd-update-lease-08

[Ballot comment]
I concur with Warren's comment (and by extension, Paul's confusion).  I would go further and question use of SHOULD here, at least because I have no idea what the threat to interoperability is if I don't do what it says.  My gut feeling is that this shouldn't use SHOULD (or any of those key words) at all.

That there are three of us asking questions about this tempts me to make it a DISCUSS, but this falls just short of something for which I want to hold up publication.

[Ballot comment]
Thank you for writing this document. I'd also like to explicitly thank David Lawrence for the comprehensive DNSDIR review (https://datatracker.ietf.org/doc/review-ietf-dnssd-update-lease-07-dnsdir-lc-tale-2023-06-14/ ), and for the followup during a natural disaster!

Like Paul Wouters I find the "the Update Lease interval should be at least 30 minutes, unless you really want it to be shorter" text to be suboptimal, but I do understand what you are trying to say.
How about something like: "By default, the minimum Update Lease option SHOULD be no shorter than 1800 seconds (30 minutes). If the requestor anticipates that the records being updated will change sooner than 30 minutes it MAY choose a shorter interval. Requestors that expect the updated records to be relatively static SHOULD request appropriately longer leases."
This says basically the same thing, but the "By default" clause seems to make it less jarring. As this is a "No Objection" ballot, feel free to ignore this suggestion...

[Ballot comment]
[note: Resolved my own discuss now that I see that deleting can be done using a delete command using dns-sd-srp]

  The Update Lease option SHOULD specify a time interval that is no
        shorter than 1800 seconds (30 minutes). Requestors MAY specify a
        shorter lease if they anticipate that the records being updated
        will change sooner than 30 minutes.

I feel this section tries to impose a restriction that it immediately breaks.
As implementer there is nothing I can do with this section except ignore this
text.




        If the Update Lease of a resource record elapses without being
        refreshed, the server MUST NOT return the expired record in
        answers to queries. The server MAY delete the record from its
        database.

The meaning here is open to interpretation. If the record is in the "database",
one could assume it is also being served. And if the record must not be returned
why is there a MAY to keep it in a "database". I think the second sentence is better
just removed and left to implementations to handle.


NIT: [I-D.ietf-dnssd-srp]  is not pointing to the latest version

[Ballot discuss]
I wonder why there is no method for a "leaving client" to cleanup and delete
its record. Eg a laptop's "lid down" event could be used to delete the records
it has a LEASE on. It could do this without any wire changes by requesting a
LEASE value of 0. It could even use a KEY_LEASE value of non-zero to still keep
a claim to the name but signal that it is currently not available. Is there a
reason this was left out of the draft? As the stated goal of the draft is a
more up to date DNS zone, this seems like a logical part of the solution to me.

[Ballot comment]
        The Update Lease option SHOULD specify a time interval that is no
        shorter than 1800 seconds (30 minutes). Requestors MAY specify a
        shorter lease if they anticipate that the records being updated
        will change sooner than 30 minutes.

I feel this section tries to impose a restriction that it immediately breaks.
As implementer there is nothing I can do with this section except ignore this
text.

There is also no way of deleting by setting an update with 0 seconds (as one
"SHOULD" not use < 3600).



        If the Update Lease of a resource record elapses without being
        refreshed, the server MUST NOT return the expired record in
        answers to queries. The server MAY delete the record from its
        database.

The meaning here is open to interpretation. If the record is in the "database",
one could assume it is also being served. And if the record must not be returned
why is there a MAY to keep it in a "database". I think the second sentence is better
just removed and left to implementations to handle.


NIT: [I-D.ietf-dnssd-srp]  is not pointing to the latest version

[Ballot comment]
# Internet AD comments for draft-ietf-dnssd-update-lease-08
CC @ekline

* comment syntax:
  - https://github.com/mnot/ietf-comments/blob/main/format.md

* "Handling Ballot Positions":
  - https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/

## Nits

### S5.2

* "a Registration a Refresh"
  -> "a Registration or a Refresh"

### S5.2.1

* "send a Refresh messages" -> "message" singular?

[Ballot comment]
# GEN AD review of draft-ietf-dnssd-update-lease-08

CC @larseggert

Thanks to Dale Worley for the General Area Review Team (Gen-ART) review
(https://mailarchive.ietf.org/arch/msg/gen-art/l7AbRwDsGmEdGeUDBgtitRVvAdw).

## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues. Review generated by the [`ietf-reviewtool`][IRT].

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments
[IRT]: https://github.com/larseggert/ietf-reviewtool

Request for Last Call review by DNSDIR Completed: Ready with Issues. Reviewer: David Lawrence. Sent review to list. Submission of review completed at an earlier date.

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Functions Operator has completed its review of draft-ietf-dnssd-update-lease-07. If any part of this review is inaccurate, please let us know.

The IANA Functions Operator understands that, upon approval of this document, there is a single action which we must complete.

In the DNS EDNS0 Option Codes (OPT) registry on the Domain Name System (DNS) Parameters registry page located at:

https://www.iana.org/assignments/dns-parameters/

the existing early registration for option code 2 is as follows:

OLD:
Value: 2
Name: UL
Status: On-hold
Reference: http://files.dns-sd.org/draft-sekar-dns-ul.txt

It will be made permanent and changed to:

NEW:
Value: 2
Name: Update Lease
Status: Standard
Reference: [ RFC-to-be ]

As this document requests registrations in an Expert Review or Specification Required (see RFC 8126) registry, we will initiate the required Expert Review via a separate request. This review must be completed before the document's IANA state can be changed to "IANA OK."

The IANA Functions Operator understands that this is the only action required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the list of actions that will be performed.

For definitions of IANA review states, please see:

https://datatracker.ietf.org/help/state/draft/iana-review

Thank you,

David Dong
IANA Services Specialist

The following Last Call announcement was sent out (ends 2023-06-13):

From: The IESG
To: IETF-Announce
CC: chris.box.ietf@gmail.com, dnssd-chairs@ietf.org, dnssd@ietf.org, draft-ietf-dnssd-update-lease@ietf.org, evyncke@cisco.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (An EDNS(0) option to negotiate Leases on DNS Updates) to Proposed Standard


The IESG has received a request from the Extensions for Scalable DNS Service
Discovery WG (dnssd) to consider the following document: - 'An EDNS(0) option
to negotiate Leases on DNS Updates'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2023-06-13. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Another IETF draft, draft-ietf-dnssd-srp-20, is related to this document. Reviewers are advised to read and review the two documents at the same time.

Abstract


  This document describes an EDNS(0) option that can be used by DNS
  Update requestors and DNS servers to include a lease lifetime in a
  DNS Update or response, allowing a server to garbage collect stale
  resource records that have been added by DNS Updates




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-dnssd-update-lease/


The following IPR Declarations may be related to this I-D:

  https://datatracker.ietf.org/ipr/1236/

# Document Shepherd Write-Up for Group Documents

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

Broad agreement. DNSSD has historically been a pretty small WG with a very small
number of vocal participants, but this draft is required for Matter (part of CSA)
and that brought in vocal participants and implementers. The draft in its current
shape represents the broad agreement of these folks.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

None in the WG. Apple have used this since 2005 but didn't seek standardisation
at the time. They brought it to the WG at IETF111 as it's a component of SRP.
There was brief debate about whether it should sit in DNSSD. It was discussed
with DNSOP chairs and agreed to call for adoption into DNSSD. The adoption call
went to both groups, but there was no pushback.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize the areas of conflict in separate email messages to the
  responsible Area Director. (It should be in a separate email because this
  questionnaire is publicly available.)

No.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

We're aware of at least two implementations already in production or going into
production soon, with more to come after publication. It is a mandatory part of
the Matter spec, so implementations are likely to expand greatly over the next
few years.

## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

We have obtained reviews from multiple individuals involved with Matter. They
support publication of the draft. No directorate reviews performed but we have
agreed with our AD that he will request INT and IoT directorate review at IETF
Last Call stage.

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

It does not contain any of the above.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

Not applicable.

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

It does not contain any of the above.

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

* Needed
Yes, there is demand for this coming from Matter and the IoT space.

* Clearly written
In general, yes. It's a short and simple document.

* Complete
Yes.

* Correctly designed
Yes, ascertained by agreement from the WG and the mechanism making sense to me.

* Ready for AD
Yes.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

I identified the following areas in draft -03, which are now resolved from -05.

* SEC area states '"This document introduces no new security considerations [on top of the base protocol spec]" is rarely true.'. The document's sentence 'The addition of a record lifetime to facilitate automated garbage collection does not itself add any significant new security concerns.' required expanding.

* TSV area states 'If a protocol contains timers, the reviewer should consider whether there is a default value given, or a formula/algorithm for managing the timer. Is there potential for multiple nodes, connections, or other protocol instances have their timers synchronize and cause undesirable effects? E.g. should the timer be randomly dithered.' Draft -03 contained potential for message synchronization after power failure, so the requirements for timer behaviour in -05 have been significantly tightened up.


11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Proposed Standard. This makes sense for a protocol definition with multiple
implementations. Datatracker is up to date.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

The disclosed IPR is at https://datatracker.ietf.org/ipr/1236/. I raised this
before I was a chair, in July 2021:
https://mailarchive.ietf.org/arch/msg/dnssd/xiCVf2dhr84Nrv7PptoHvYiLTzY/
There hasn't been any pushback from the WG about this IPR.

Both authors have explicitly confirmed no additional IPR:
https://mailarchive.ietf.org/arch/msg/dnssd/95pR6si77GlgQJE7oplEjRDDZ-s/
https://mailarchive.ietf.org/arch/msg/dnssd/wxv0fy925st5FlKHaJM_z_nh91I/

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

Confirmation received from the authors, Roger Pantos, Gabriel, Jonathan, Abtin, Kangping, Nathan, Steve, Esko, Peter, Marc and Tim. I was unable to find current contact details for Kiren Sekar & Chris Sharp.


14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

ID Nits
-------
No nits found, other than referring to srp-18 rather than srp-19.

Content Guidelines
------------------
Draft -03 contained the issues described below. None of these remain in -06, so they are included only for interest.

* The Security Considerations didn't meet the standard of "meaningful".

* IANA Considerations weren't entirely clear.

* Two abbreviations lacked expansions on first use. They are not considered well-known in the RFC Editor's abbreviations list:
EDNS(0) Extension Mechanisms for DNS (EDNS(0))
DNS-SD      DNS-based Service Discovery (DNS-SD)

* The following uses of SHOULD failed to state valid reasons for varying from the recommendation, and the implications of doing so.
4.1 DNS Update requestors SHOULD send an Update Lease option with any DNS Update that is not intended to be present indefinitely.
4.1 The Update Lease option SHOULD specify a time interval that is no shorter than 30 minutes (1800 seconds).
5.1 The Refresh message SHOULD NOT include any update prerequisites that would, if the state produced by the previous update or Refresh is still in effect, fail.
5.1 The update SHOULD NOT be constructed to fail in the case that the state produced by the previous update or Refresh has for some reason been garbage collected.
5.2 Requestors SHOULD Refresh resource records after 75% of the original lease has elapsed.
5.2 If the requestor uses UDP and does not receive a response from the server, the requestor SHOULD retry after 2 seconds.
5.2 The requestor SHOULD continue to retry, doubling the length of time between each retry, or retry using TCP.
5.2.1 If the requestor uses UDP, the requestor MUST NOT coalesce Refresh messages if doing so would cause truncation of the message; in this case, either multiple messages or TCP SHOULD be used.


15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

No.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

None.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.

20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

The considerations section was made clearer. No other issues arise.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

None.

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

# Document Shepherd Write-Up for Group Documents

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

Broad agreement. DNSSD has historically been a pretty small WG with a very small
number of vocal participants, but this draft is required for Matter (part of CSA)
and that brought in vocal participants and implementers. The draft in its current
shape represents the broad agreement of these folks.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

None in the WG. Apple have used this since 2005 but didn't seek standardisation
at the time. They brought it to the WG at IETF111 as it's a component of SRP.
There was brief debate about whether it should sit in DNSSD. It was discussed
with DNSOP chairs and agreed to call for adoption into DNSSD. The adoption call
went to both groups, but there was no pushback.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize the areas of conflict in separate email messages to the
  responsible Area Director. (It should be in a separate email because this
  questionnaire is publicly available.)

No.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

We're aware of at least two implementations already in production or going into
production soon, with more to come after publication. It is a mandatory part of
the Matter spec, so implementations are likely to expand greatly over the next
few years.

## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

We have obtained reviews from multiple individuals involved with Matter. They
support publication of the draft. No directorate reviews performed but we have
agreed with our AD that he will request INT and IoT directorate review at IETF
Last Call stage.

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

It does not contain any of the above.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

Not applicable.

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

It does not contain any of the above.

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

* Needed
Yes, there is demand for this coming from Matter and the IoT space.

* Clearly written
In general, yes. It's a short and simple document.

* Complete
Yes.

* Correctly designed
Yes, ascertained by agreement from the WG and the mechanism making sense to me.

* Ready for AD
Yes.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

I identified the following areas in draft -03, which are now resolved from -05.

* SEC area states '"This document introduces no new security considerations [on top of the base protocol spec]" is rarely true.'. The document's sentence 'The addition of a record lifetime to facilitate automated garbage collection does not itself add any significant new security concerns.' required expanding.

* TSV area states 'If a protocol contains timers, the reviewer should consider whether there is a default value given, or a formula/algorithm for managing the timer. Is there potential for multiple nodes, connections, or other protocol instances have their timers synchronize and cause undesirable effects? E.g. should the timer be randomly dithered.' Draft -03 contained potential for message synchronization after power failure, so the requirements for timer behaviour in -05 have been significantly tightened up.


11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Proposed Standard. This makes sense for a protocol definition with multiple
implementations. Datatracker is up to date.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

The disclosed IPR is at https://datatracker.ietf.org/ipr/1236/. I raised this
before I was a chair, in July 2021:
https://mailarchive.ietf.org/arch/msg/dnssd/xiCVf2dhr84Nrv7PptoHvYiLTzY/
There hasn't been any pushback from the WG about this IPR.

Both authors have explicitly confirmed no additional IPR:
https://mailarchive.ietf.org/arch/msg/dnssd/95pR6si77GlgQJE7oplEjRDDZ-s/
https://mailarchive.ietf.org/arch/msg/dnssd/wxv0fy925st5FlKHaJM_z_nh91I/

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

Confirmation received from the authors, Roger Pantos, Gabriel, Jonathan, Abtin, Kangping, Nathan, Steve, Esko, Peter, Marc and Tim. I was unable to find current contact details for Kiren Sekar & Chris Sharp.


14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

ID Nits
-------
No nits found, other than referring to srp-18 rather than srp-19.

Content Guidelines
------------------
Draft -03 contained the issues described below. None of these remain in -06, so they are included only for interest.

* The Security Considerations didn't meet the standard of "meaningful".

* IANA Considerations weren't entirely clear.

* Two abbreviations lacked expansions on first use. They are not considered well-known in the RFC Editor's abbreviations list:
EDNS(0) Extension Mechanisms for DNS (EDNS(0))
DNS-SD      DNS-based Service Discovery (DNS-SD)

* The following uses of SHOULD failed to state valid reasons for varying from the recommendation, and the implications of doing so.
4.1 DNS Update requestors SHOULD send an Update Lease option with any DNS Update that is not intended to be present indefinitely.
4.1 The Update Lease option SHOULD specify a time interval that is no shorter than 30 minutes (1800 seconds).
5.1 The Refresh message SHOULD NOT include any update prerequisites that would, if the state produced by the previous update or Refresh is still in effect, fail.
5.1 The update SHOULD NOT be constructed to fail in the case that the state produced by the previous update or Refresh has for some reason been garbage collected.
5.2 Requestors SHOULD Refresh resource records after 75% of the original lease has elapsed.
5.2 If the requestor uses UDP and does not receive a response from the server, the requestor SHOULD retry after 2 seconds.
5.2 The requestor SHOULD continue to retry, doubling the length of time between each retry, or retry using TCP.
5.2.1 If the requestor uses UDP, the requestor MUST NOT coalesce Refresh messages if doing so would cause truncation of the message; in this case, either multiple messages or TCP SHOULD be used.


15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

No.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

None.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.

20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

The considerations section was made clearer. No other issues arise.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

None.

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

# Document Shepherd Write-Up for Group Documents

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

Broad agreement. DNSSD has historically been a pretty small WG with a very small
number of vocal participants, but this draft is required for Matter (part of CSA)
and that brought in vocal participants and implementers. The draft in its current
shape represents the broad agreement of these folks.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

None in the WG. Apple have used this since 2005 but didn't seek standardisation
at the time. They brought it to the WG at IETF111 as it's a component of SRP.
There was brief debate about whether it should sit in DNSSD. It was discussed
with DNSOP chairs and agreed to call for adoption into DNSSD. The adoption call
went to both groups, but there was no pushback.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize the areas of conflict in separate email messages to the
  responsible Area Director. (It should be in a separate email because this
  questionnaire is publicly available.)

No.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

We're aware of at least two implementations already in production or going into
production soon, with more to come after publication. It is a mandatory part of
the Matter spec, so implementations are likely to expand greatly over the next
few years.

## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

We have obtained reviews from multiple individuals involved with Matter. They
support publication of the draft. No directorate reviews performed but we have
agreed with our AD that he will request INT and IoT directorate review at IETF
Last Call stage.

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

It does not contain any of the above.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

Not applicable.

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

It does not contain any of the above.

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

* Needed
Yes, there is demand for this coming from Matter and the IoT space.

* Clearly written
In general, yes. It's a short and simple document.

* Complete
Yes.

* Correctly designed
Yes, ascertained by agreement from the WG and the mechanism making sense to me.

* Ready for AD
Yes, as soon as it has completed the second WGLC which is about to be initiated.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

I identified the following areas in draft -03, which are now resolved in -05.

* SEC area states '"This document introduces no new security considerations [on top of the base protocol spec]" is rarely true.'. The document's sentence 'The addition of a record lifetime to facilitate automated garbage collection does not itself add any significant new security concerns.' required expanding.

* TSV area states 'If a protocol contains timers, the reviewer should consider whether there is a default value given, or a formula/algorithm for managing the timer. Is there potential for multiple nodes, connections, or other protocol instances have their timers synchronize and cause undesirable effects? E.g. should the timer be randomly dithered.' Draft -03 contained potential for message synchronization after power failure, so the requirements for timer behaviour in -05 have been significantly tightened up.


11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Proposed Standard. This makes sense for a protocol definition with multiple
implementations. Datatracker is up to date.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

The disclosed IPR is at https://datatracker.ietf.org/ipr/1236/. I raised this
before I was a chair, in July 2021:
https://mailarchive.ietf.org/arch/msg/dnssd/xiCVf2dhr84Nrv7PptoHvYiLTzY/
There hasn't been any pushback from the WG about this IPR.

Both authors have explicitly confirmed no additional IPR:
https://mailarchive.ietf.org/arch/msg/dnssd/95pR6si77GlgQJE7oplEjRDDZ-s/
https://mailarchive.ietf.org/arch/msg/dnssd/wxv0fy925st5FlKHaJM_z_nh91I/

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

Confirmation received from the authors, Roger Pantos, Gabriel, Jonathan, Abtin, Kangping, Nathan, Steve, Esko, Peter, Marc and Tim. I was unable to find current contact details for Kiren Sekar & Chris Sharp.


14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

ID Nits
-------
"No nits found."

Content Guidelines
------------------
Draft -03 contained the issues described below. None of these remain in -05, so they are included only for interest.

* The Security Considerations didn't meet the standard of "meaningful".

* IANA Considerations weren't entirely clear.

* Two abbreviations lacked expansions on first use. They are not considered well-known in the RFC Editor's abbreviations list:
EDNS(0) Extension Mechanisms for DNS (EDNS(0))
DNS-SD      DNS-based Service Discovery (DNS-SD)

* The following uses of SHOULD failed to state valid reasons for varying from the recommendation, and the implications of doing so.
4.1 DNS Update requestors SHOULD send an Update Lease option with any DNS Update that is not intended to be present indefinitely.
4.1 The Update Lease option SHOULD specify a time interval that is no shorter than 30 minutes (1800 seconds).
5.1 The Refresh message SHOULD NOT include any update prerequisites that would, if the state produced by the previous update or Refresh is still in effect, fail.
5.1 The update SHOULD NOT be constructed to fail in the case that the state produced by the previous update or Refresh has for some reason been garbage collected.
5.2 Requestors SHOULD Refresh resource records after 75% of the original lease has elapsed.
5.2 If the requestor uses UDP and does not receive a response from the server, the requestor SHOULD retry after 2 seconds.
5.2 The requestor SHOULD continue to retry, doubling the length of time between each retry, or retry using TCP.
5.2.1 If the requestor uses UDP, the requestor MUST NOT coalesce Refresh messages if doing so would cause truncation of the message; in this case, either multiple messages or TCP SHOULD be used.


15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

No.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

None.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.

20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

The considerations section was made clearer. No other issues arise.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

None.

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

# Document Shepherd Write-Up for Group Documents

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

Broad agreement. DNSSD has historically been a pretty small WG with a very small
number of vocal participants, but this draft is required for Matter (part of CSA)
and that brought in vocal participants and implementers. The draft in its current
shape represents the broad agreement of these folks.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

None in the WG. Apple have used this since 2005 but didn't seek standardisation
at the time. They brought it to the WG at IETF111 as it's a component of SRP.
There was brief debate about whether it should sit in DNSSD. It was discussed
with DNSOP chairs and agreed to call for adoption into DNSSD. The adoption call
went to both groups, but there was no pushback.

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize the areas of conflict in separate email messages to the
  responsible Area Director. (It should be in a separate email because this
  questionnaire is publicly available.)

No.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

We're aware of at least two implementations already in production or going into
production soon, with more to come after publication. It is a mandatory part of
the Matter spec, so implementations are likely to expand greatly over the next
few years.

## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

We have obtained reviews from multiple individuals involved with Matter. They
support publication of the draft. No directorate reviews performed but we have
agreed with our AD that he will request INT and IoT directorate review at IETF
Last Call stage.

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

It does not contain any of the above.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

Not applicable.

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

It does not contain any of the above.

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

* Needed
Yes, there is demand for this coming from Matter and the IoT space.

* Clearly written
In general, yes. It's a short and simple document.

* Complete
Yes.

* Correctly designed
Yes, ascertained by agreement from the WG and the mechanism making sense to me.

* Ready for AD
Yes, as soon as it has completed the second WGLC which is about to be initiated.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

I identified the following areas in draft -03, which are now resolved in -05.

* SEC area states '"This document introduces no new security considerations [on top of the base protocol spec]" is rarely true.'. The document's sentence 'The addition of a record lifetime to facilitate automated garbage collection does not itself add any significant new security concerns.' required expanding.

* TSV area states 'If a protocol contains timers, the reviewer should consider whether there is a default value given, or a formula/algorithm for managing the timer. Is there potential for multiple nodes, connections, or other protocol instances have their timers synchronize and cause undesirable effects? E.g. should the timer be randomly dithered.' Draft -03 contained potential for message synchronization after power failure, so the requirements for timer behaviour in -05 have been significantly tightened up.


11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

Proposed Standard. This makes sense for a protocol definition with multiple
implementations. Datatracker is up to date.

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

The disclosed IPR is at https://datatracker.ietf.org/ipr/1236/. I raised this
before I was a chair, in July 2021:
https://mailarchive.ietf.org/arch/msg/dnssd/xiCVf2dhr84Nrv7PptoHvYiLTzY/
There hasn't been any pushback from the WG about this IPR.

Both authors have explicitly confirmed no additional IPR:
https://mailarchive.ietf.org/arch/msg/dnssd/95pR6si77GlgQJE7oplEjRDDZ-s/
https://mailarchive.ietf.org/arch/msg/dnssd/wxv0fy925st5FlKHaJM_z_nh91I/

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

Confirmation received from the authors, Roger Pantos, Gabriel, Jonathan, Abtin, Kangping, Nathan, Steve, Esko, Peter, Marc. Tim Wicinski is pending. I was unable to find current contact details for Kiren Sekar & Chris Sharp.


14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

ID Nits
-------
"No nits found."

Content Guidelines
------------------
Draft -03 contained the issues described below. None of these remain in -05, so they are included only for interest.

* The Security Considerations didn't meet the standard of "meaningful".

* IANA Considerations weren't entirely clear.

* Two abbreviations lacked expansions on first use. They are not considered well-known in the RFC Editor's abbreviations list:
EDNS(0) Extension Mechanisms for DNS (EDNS(0))
DNS-SD      DNS-based Service Discovery (DNS-SD)

* The following uses of SHOULD failed to state valid reasons for varying from the recommendation, and the implications of doing so.
4.1 DNS Update requestors SHOULD send an Update Lease option with any DNS Update that is not intended to be present indefinitely.
4.1 The Update Lease option SHOULD specify a time interval that is no shorter than 30 minutes (1800 seconds).
5.1 The Refresh message SHOULD NOT include any update prerequisites that would, if the state produced by the previous update or Refresh is still in effect, fail.
5.1 The update SHOULD NOT be constructed to fail in the case that the state produced by the previous update or Refresh has for some reason been garbage collected.
5.2 Requestors SHOULD Refresh resource records after 75% of the original lease has elapsed.
5.2 If the requestor uses UDP and does not receive a response from the server, the requestor SHOULD retry after 2 seconds.
5.2 The requestor SHOULD continue to retry, doubling the length of time between each retry, or retry using TCP.
5.2.1 If the requestor uses UDP, the requestor MUST NOT coalesce Refresh messages if doing so would cause truncation of the message; in this case, either multiple messages or TCP SHOULD be used.


15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

No.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

None.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

No.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

No.

20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

The considerations section was made clearer. No other issues arise.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

None.

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/