



Internet Engineering Task Force                                 S. Huque
Internet-Draft                                                Salesforce
Updates: 6895 (if approved)                                   M. Andrews
Intended status: Standards Track             Internet Systems Consortium
Expires: 11 May 2026                                     7 November 2025


                  Private Use Q and Meta-types for DNS
                 draft-huque-dnsop-private-metatypes-01

Abstract

   The DNS protocol supports three subcategories of Resource Record
   Types (RRTYPE): data types, QTYPES, and Meta-TYPES.  There is a
   dedicated subrange of the RRTYPE space for Q and Meta-TYPES
   (128-155).  The DNS protocol also defines a subrange of the RRTYPE
   space dedicated to private use (65280-65534), however this subrange
   has no corresponding subdivision into data versus Q and Meta-TYPES.
   This document proposes such a subdivision.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Source for this draft and an issue tracker can be found at
   https://github.com/shuque/ietf-private-metatypes.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on 11 May 2026.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Private Q and Meta-Types Range  . . . . . . . . . . . . . . .   3
   3.  Handling Unknown Q and Meta-Types . . . . . . . . . . . . . .   3
   4.  Updates to RFCs . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Open Questions  . . . . . . . . . . . . . . . . . . . . . . .   3
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   As described in DNS IANA Considerations [RFC6895], the DNS protocol
   supports three subcategories of Resource Record Types (RRTYPE): data
   types, QTYPES, and Meta-TYPES.  There is a dedicated subrange of the
   RRTYPE space for Q and Meta-TYPES (128-155).  The DNS protocol also
   defines a subrange of the RRTYPE space dedicated to private use
   (65280-65534), however this subrange has no corresponding subdivision
   into data versus Q and Meta-TYPES.  This document proposes such a
   subdivision.

   Informational: There are currently four Meta-TYPEs assigned: OPT
   [RFC6891], TSIG, TKEY, and NXNAME.  There are currently five QTYPEs
   assigned: * (ALL/ANY), MAILA, MAILB, AXFR, and IXFR.  Notably the OPT
   meta-type is not assigned from the Q and Meta-Type space (presumably
   because it predated the current RR type space classification).

   Many resolvers implementations treat queries for Q and Meta-types
   specially.  If the query is for an unknown Q or Meta-type or for a
   Meta-type with undefined (or forbidden) query behavior, the resolver
   will treat it like an invalid query.  It will not attempt to perform
   iterative resolution for it, and return an error back to the querier,
   typically format error (FORMERR).  This kind of behavior is not
   possible with private types, since the private RR type space has no
   differentiation of data types versus Q and Meta-TYPES.  This makes it



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   difficult to experiment with new Q or Meta-TYPES utilizing private RR
   types.  Notably, this posed challenges when the NXNAME Meta-type
   [RFC9824] was deployed in the field using a private RR type code,
   prior to standardization.

2.  Private Q and Meta-Types Range

   The definition of new Q and Meta-types is expected to be quite
   infrequent, so only a small subrange should be sufficient, e.g. 16
   code points.  We present two options, and should choose one.

   Option 1: Subset of "Reserved for Private Use" Range:

           65280-65295     Private Use Q amd Meta-types             (16)
           65296-65534     Private Use Data-types                  (239)

   Option 2: Subset of "Reserved for Future Use" Range, immediately
   before and adjacent to the current Private Use Range:

           65264-65279     Private Use Q and Meta-types             (16)
           65280-65534     Private Use Data-types                  (255)

3.  Handling Unknown Q and Meta-Types

   DNS servers MUST return an error when receiving a query for an
   unknown Q or Meta-Type.  This applies generally to both private and
   non-private Q and Meta-Types.  The recommended response code is
   Format Error (FORMERR), preferably accompanied with an Extended DNS
   Error code of 'Invalid Query Type' (Info-Code 30).  In particular,
   resolvers should not attempt to perform iterative resolution for such
   queries.

4.  Updates to RFCs

   Update the RR type ranges described in RFC 6895 with the information
   from Section 2.

5.  Open Questions

   Is this proposal best described in a separate RFC, or should it
   instead be part of an update to the DNS IANA Considerations RFC
   [RFC6895]?

6.  Security Considerations

   None.





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7.  IANA Considerations

   See Section 2.

8.  References

8.1.  Normative References

   [RFC6895]  Eastlake 3rd, D., "Domain Name System (DNS) IANA
              Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895,
              April 2013, <https://www.rfc-editor.org/info/rfc6895>.

8.2.  Informative References

   [RFC9824]  Huque, S., Elmerot, C., and O. Gudmundsson, "Compact
              Denial of Existence in DNSSEC", RFC 9824,
              DOI 10.17487/RFC9824, September 2025,
              <https://www.rfc-editor.org/info/rfc9824>.

Authors' Addresses

   Shumon Huque
   Salesforce
   Email: shuque@gmail.com


   Mark Andrews
   Internet Systems Consortium
   Email: marka@isc.org






















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