Special Use Domain Name 'ipv4only.arpa'
RFC 8880

Document Type RFC - Proposed Standard (August 2020; No errata)
Updates RFC 7050
Authors Stuart Cheshire  , David Schinazi 
Last updated 2020-08-31
Stream IETF
Formats plain text html xml pdf htmlized bibtex
Reviews
Stream WG state (None)
Document shepherd Warren Kumari
Shepherd write-up Show (last changed 2020-01-19)
IESG IESG state RFC 8880 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Warren Kumari
Send notices to (None)
IANA IANA review state Version Changed - Review Needed
IANA action state RFC-Ed-Ack


Internet Engineering Task Force (IETF)                       S. Cheshire
Request for Comments: 8880                                    Apple Inc.
Updates: 7050                                                D. Schinazi
Category: Standards Track                                     Google LLC
ISSN: 2070-1721                                              August 2020

                Special Use Domain Name 'ipv4only.arpa'

Abstract

   NAT64 (Network Address and Protocol Translation from IPv6 Clients to
   IPv4 Servers) allows client devices using IPv6 to communicate with
   servers that have only IPv4 connectivity.

   The specification for how a client discovers its local network's
   NAT64 prefix (RFC 7050) defines the special name 'ipv4only.arpa' for
   this purpose.  However, in its Domain Name Reservation Considerations
   section (Section 8.1), that specification (RFC 7050) indicates that
   the name actually has no particularly special properties that would
   require special handling.

   Consequently, despite the well-articulated special purpose of the
   name, 'ipv4only.arpa' was not recorded in the Special-Use Domain
   Names registry as a name with special properties.

   This document updates RFC 7050.  It describes the special treatment
   required and formally declares the special properties of the name.
   It also adds similar declarations for the corresponding reverse
   mapping names.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8880.

Copyright Notice

   Copyright (c) 2020 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
   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
     1.1.  Conventions and Terminology
   2.  Reasons to Declare 'ipv4only.arpa' as Special
   3.  Consequences of 'ipv4only.arpa' Not Being Declared Special
     3.1.  Consequences for Name Resolution APIs and Libraries
     3.2.  Consequences for DNS64 Implementations
   4.  Remedies
   5.  Security Considerations
   6.  IANA Considerations
   7.  Domain Name Reservation Considerations
     7.1.  Special Use Domain Name 'ipv4only.arpa'
     7.2.  Names '170.0.0.192.in-addr.arpa' and
           '171.0.0.192.in-addr.arpa'
       7.2.1.  ip6.arpa Reverse Mapping PTR Records
   8.  References
     8.1.  Normative References
     8.2.  Informative References
   Appendix A.  Example BIND 9 Configuration
   Acknowledgements
   Authors' Addresses

1.  Introduction

   NAT64 (Network Address and Protocol Translation from IPv6 Clients to
   IPv4 Servers) [RFC6146] allows client devices using IPv6 to
   communicate with servers that have only IPv4 connectivity.

   DNS64 (DNS Extensions for Network Address Translation from IPv6
   Clients to IPv4 Servers) [RFC6147] facilitates use of NAT64 by
   clients by generating synthesized IPv6 addresses for IPv4 servers
   that have no IPv6 address of their own, or by communicating the local
   network's NAT64 prefix to clients so that they can perform the IPv6
   address synthesis themselves.

   The specification for how a client discovers its local network's
   NAT64 prefix [RFC7050] defines the special name 'ipv4only.arpa' for
   this purpose, but in its Domain Name Reservation Considerations
   section (Section 8.1), that specification [RFC7050] indicates that
   the name actually has no particularly special properties that would
   require special handling and does not request IANA to record the name
   in the Special-Use Domain Names registry [SUDN].

   Consequently, despite the well-articulated special purpose of the
   name, 'ipv4only.arpa' was not recorded in the Special-Use Domain
   Names registry [SUDN] as a name with special properties.

   This omission was discussed in the document "Special-Use Domain Names
   Problem Statement" [RFC8244].

   As a result of this omission, in cases where software needs to give
   this name special treatment in order for it to work correctly, there
Show full document text