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Network Working Group                                         P. Hoffman
Internet-Draft                                                     ICANN
Intended status: Standards Track                         October 1, 2018
Expires: April 4, 2019


              IANA Registry for Special Labels in the DNS
                  draft-hoffman-dns-special-labels-00

Abstract

   This document defines an new IANA registry for special labels in the
   DNS.  The registry is useful because the labels cause special
   handling in DNS entities such as stub resolvers, recursive resolvers,
   and applications that use DNS, and developers of software for those
   entities should be aware of the many types of special labels in use.

   [[ A GitHub repo for this document is at
   https://github.com/paulehoffman/dns-special-labels ]]

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 4, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definition of the New IANA Registry . . . . . . . . . . . . .   3
   3.  Existing Special Labels . . . . . . . . . . . . . . . . . . .   3
     3.1.  The Root Label  . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Underscore Labels . . . . . . . . . . . . . . . . . . . .   3
     3.3.  IDNA  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.4.  Sentinel  . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.5.  MTA-STS . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Some DNS-related RFCs define labels that are treated specially by
   stub resolvers, by recursive resolvers, and by applications.  It
   would be useful for DNS software developers to know what the entire
   set of such special labels are so they can determine if their
   software needs to handle those labels different than other labels.
   This document defines an IANA registry for special labels and lists
   the initial entries for that registry.

   The special labels defined in the various RFCs were developed after
   extensive IETF evaluation of alternative patterns and approaches in
   light of the desired behavior of the associated protocols.  The group
   designing each protocol looked at the many different ways that the
   protocol might be best deployed.

1.1.  Terminology

   In this document, "left-most label" means the label that appears at
   the left of a domain name when it is wire format or presentation
   format, as defined in [I-D.ietf-dnsop-terminology-bis].  In an
   application that uses IDNA [RFC5891] with one or more right-to-left
   labels, the order of the labels might appear different in the
   application.




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2.  Definition of the New IANA Registry

   The creation of the registry is defined in Section 4.

   @@ Proposed rule for getting in the registry: @@

   A label or label-type can be added to the registry only by IESG
   approval.  This approval will likely come when an Internet Draft is
   progressed toward publication by the RFC Editor, but can come at any
   time.  The reason to require IESG approval as compared to something
   less onerous such as "expert review" is that developers who rely on
   the registry will expect it to contain labels and label types that
   are relatively stable.

   The columns of the registry are as follows:

   @@ Define the columns here @@

3.  Existing Special Labels

   The following describes the labels that are the initial contents of
   the registry described in Section 4.

3.1.  The Root Label

   According to [RFC1035], a zero-length label always indicates the root
   label in a domain name.

3.2.  Underscore Labels

   In many protocols, one or more of the left-most labels might be a
   label that starts with an underscore (_) character.  Those labels are
   considered special within the context of those protocols.

   The use of underscore labels is described in
   [I-D.ietf-dnsop-attrleaf] and [I-D.ietf-dnsop-attrleaf-fix].

3.3.  IDNA

   [RFC5891] defines "A-labels" as labels that begin with the characters
   "xn-".  These labels can appear at any position in a domain name.

3.4.  Sentinel

   [I-D.ietf-dnsop-kskroll-sentinel] (if approved as an RFC) defines
   root-key-sentinel-is-ta-<key-tag> and root-key-sentinel-not-ta-<key-
   tag> as special labels when they are the left-most label.  In these




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   labels, "<key-tag>" is an unsigned decimal integer that is zero-
   padded to five digits.

3.5.  MTA-STS

   [RFC8461] defines "mta-sts" as as special label when it is the left-
   most label.

4.  IANA Considerations

   @@@ Formally define the new registry here @@@

5.  Security Considerations

   This document doesn't introduce any new security considerations.

6.  References

6.1.  Normative References

   [I-D.ietf-dnsop-attrleaf]
              Crocker, D., "DNS Scoped Data Through "Underscore" Naming
              of Attribute Leaves", draft-ietf-dnsop-attrleaf-13 (work
              in progress), August 2018.

   [I-D.ietf-dnsop-attrleaf-fix]
              Crocker, D., "DNS Attrleaf Changes: Fixing Specifications
              with Underscored Node Name Use", draft-ietf-dnsop-
              attrleaf-fix-04 (work in progress), August 2018.

   [I-D.ietf-dnsop-kskroll-sentinel]
              Huston, G., Damas, J., and W. Kumari, "A Root Key Trust
              Anchor Sentinel for DNSSEC", draft-ietf-dnsop-kskroll-
              sentinel-15 (work in progress), July 2018.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <https://www.rfc-editor.org/info/rfc1035>.

   [RFC5891]  Klensin, J., "Internationalized Domain Names in
              Applications (IDNA): Protocol", RFC 5891,
              DOI 10.17487/RFC5891, August 2010,
              <https://www.rfc-editor.org/info/rfc5891>.

   [RFC8461]  Margolis, D., Risher, M., Ramakrishnan, B., Brotman, A.,
              and J. Jones, "SMTP MTA Strict Transport Security (MTA-
              STS)", RFC 8461, DOI 10.17487/RFC8461, September 2018,
              <https://www.rfc-editor.org/info/rfc8461>.



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6.2.  Informative References

   [I-D.ietf-dnsop-terminology-bis]
              Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
              Terminology", draft-ietf-dnsop-terminology-bis-14 (work in
              progress), September 2018.

Appendix A.  Acknowledgements

   @@@ List folks who think of other new labels to add or come up with
   additional wording for the document @@@

Author's Address

   Paul Hoffman
   ICANN

   Email: paul.hoffman@icann.org

































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