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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,
.

[RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
RFC 6761, DOI 10.17487/RFC6761, February 2013,
.

[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,
.

5.2. Informative References

[SUDN] "Special-Use Domain Names Registry", 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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