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Network Working Group                                        S. Cheshire
Internet-Draft                                               D. Schinazi
Updates: 7050 (if approved)                                   Apple Inc.
Intended status: Standards Track                        January 28, 2016
Expires: July 31, 2016


                Special Use Domain Name 'ipv4only.arpa'
                draft-cheshire-sudn-ipv4only-dot-arpa-00

Abstract

   The document "Discovery of the IPv6 Prefix Used for IPv6 Address
   Synthesis" [RFC7050] specifies the Special Use Domain Name
   'ipv4only.arpa', with certain precise special properties, but
   neglected to include a Domain Name Reservation Considerations section
   [RFC6761] formalizing those special properties.  This document
   updates RFC 7050 and formally specifies the Special Use Domain Name
   rules for ipv4only.arpa.

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 http://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 July 31, 2016.

Copyright Notice

   Copyright (c) 2016 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
   (http://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.


1.  Introduction

   The document "Discovery of the IPv6 Prefix Used for IPv6 Address
   Synthesis" [RFC7050] specifies the Special Use Domain Name
   'ipv4only.arpa', with certain precise special properties, but
   neglected to include a Domain Name Reservation Considerations section
   [RFC6761] formally stating those special properties.

   As a result of the name 'ipv4only.arpa' not being formally declared
   to have special properties, there was no mandate for software to
   treat this name specially.  Queries for this name are handled
   normally, and result in queries to the 'arpa' name servers.  At
   times, for reasons that are as yet unclear, the 'arpa' name servers
   have been observed to be slow or unresponsive.  The failures of these
   'ipv4only.arpa' queries result in failures of software that depends
   on them for NAT64 address synthesis.  Also, having millions of
   devices around the world depend on these answers generates pointless
   additional load on the 'arpa' name servers, which is completely
   unnecessary when this name is defined, by Internet Standard, to have
   only two address records, 192.0.0.170 and 192.0.0.171, and no other
   records.

   To remedy this situation, this document updates RFC 7050 and
   specifies the formal Special Use Domain Name rules for ipv4only.arpa.


2.  Conventions and Terminology Used in this Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119].


3.  Security Considerations

   Hard-coding the answers for ipv4only.arpa queries avoids the risk of
   malicious devices intercepting those queries and returning incorrect
   answers.







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4.  IANA Considerations

   [Once published, this should say] IANA has recorded the name
   'ipv4only.arpa' in the Special-Use Domain Names registry [SUDN].

4.1.  Domain Name Reservation Considerations

   The name 'ipv4only.arpa' is special [RFC6761] in the following ways:

   1.  Users should never have reason to encounter the ipv4only.arpa
       domain nanme.  If they do, queries for ipv4only.arpa should
       result in the answers specified in RFC 7050.  Users have no need
       to know that ipv4only.arpa is special.

   2.  Application software may explicitly use the name ipv4only.arpa
       for NAT64 address synthesis, and expect to get the answers
       specified in RFC 7050.  If application software encounters the
       name ipv4only.arpa as user input, the application software should
       resolve that name as usual and need not treat it in any special
       way.

   3.  Name resolution APIs and libraries SHOULD NOT recognize
       ipv4only.arpa as special and SHOULD NOT treat it differently.
       Name resolution APIs SHOULD send queries for this name to their
       configured recursive/caching DNS server(s).

   4.  Recursive/caching DNS servers SHOULD recognize ipv4only.arpa as
       special and SHOULD NOT, by default, attempt to look up NS records
       for it, or otherwise query authoritative DNS servers in an
       attempt to resolve this name.  Instead, recursive/caching DNS
       servers SHOULD, by default, act as authoritative and generate
       immediate responses for all such queries.  Traditional recursive/
       caching DNS servers that act as authoritative for this name MUST
       generate only the 192.0.0.170 and 192.0.0.171 responses for these
       queries, and no others.  DNS64 recursive/caching DNS servers MUST
       generate the 192.0.0.170 and 192.0.0.171 address record responses
       for these queries, and MUST generate the appropriate synthesized
       IPv6 address record responses for all AAAA queries.  This is to
       avoid unnecessary load on the 'arpa' name servers.

   5.  Traditional authoritative DNS servers SHOULD recognize
       ipv4only.arpa as special and SHOULD, by default, generate
       immediate negative responses for all such queries, unless
       explicitly configured otherwise by the administrator (which only
       applies to the administrators of the 'arpa' namespace).

   6.  DNS server operators MUST understand that ipv4only.arpa is a
       special name, with answers specified by Internet Standard.



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   7.  DNS Registries/Registrars MUST understand that ipv4only.arpa is a
       special name, with answers specified by Internet Standard.


5.  References

5.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
              RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC6761]  Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
              RFC 6761, DOI 10.17487/RFC6761, February 2013,
              <http://www.rfc-editor.org/info/rfc6761>.

   [RFC7050]  Savolainen, T., Korhonen, J., and D. Wing, "Discovery of
              the IPv6 Prefix Used for IPv6 Address Synthesis",
              RFC 7050, DOI 10.17487/RFC7050, November 2013,
              <http://www.rfc-editor.org/info/rfc7050>.

5.2.  Informative References

   [SUDN]     "Special-Use Domain Names Registry", <http://www.iana.org/
              assignments/special-use-domain-names/>.


Authors' Addresses

   Stuart Cheshire
   Apple Inc.
   1 Infinite Loop
   Cupertino, California  95014
   USA

   Phone: +1 408 974 3207
   Email: cheshire@apple.com













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   David Schinazi
   Apple Inc.
   1 Infinite Loop
   Cupertino, California  95014
   USA

   Phone: +1 669 227 9921
   Email: dschinazi@apple.com











































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