Network Working Group                                           J. Abley
Internet-Draft                                                     ICANN
Updates: 3172 (if approved)                               O. Gudmundsson
Intended status: BCP                                       Shinkuro Inc.
Expires: July 22, 2010                                  January 18, 2010

       The Eternal Non-Existence of SINK.ARPA (and other stories)


   This document specifies a fully-qualified domain name in the Domain
   Name System (DNS) that can be relied upon never to exist.  The
   availability of a name in the DNS which is guaranteed not to exist
   has useful operational applications.

   This document also provides a procedural framework for other names
   that have special characteristics to be reserved, and for those
   special characteristics to be codified as modifications to the normal
   ARPA administration process.

Status of this Memo

   This Internet-Draft is submitted to IETF 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 July 22, 2010.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
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   described in the BSD License.

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1.  Introduction

   The Domain Name System (DNS) is described in [RFC1034] and [RFC1035].
   This document has three purposes:

   1.  to create a new IANA registry called "ARPA Reserved Names" (see
       Section 4);

   2.  to define the special considerations of a single name SINK.ARPA,
       a name which is defined never to exist (see Section 2);

   3.  to allow the procedures by which the ARPA zone is maintained, as
       documented in [RFC3172], to be modified for names present in the
       ARPA Reserved Names registry according to the special
       characteristics of those names (see Section 5).

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   The special considerations for the name SINK.ARPA are that the name
   SINK.ARPA shall be guaranteed never to have any resource records
   associated with it.  That is, the domain does not exist and queries
   for it will result in name errors (NXDOMAIN).  The reliable non-
   existence of a globally-consistent and formally-defined name has some
   operational utility (see Section 3 for examples).

   Various top-level domains are reserved by [RFC2606], including
   "INVALID".  The use of "INVALID" as a codified, non-existent domain
   was considered.  However:

   o  INVALID is poorly characterised from a DNS perspective in
      [RFC2606]; that is, the specification that INVALID does not exist
      as a Top Level Domain (TLD) is imprecise given the various uses of
      the term TLD in policy forums;

   o  the contents of the root zone are derived by interaction with many
      inter-related policy-making bodies, whereas the administrative and
      technical processes relating to the ARPA zone are much more
      clearly defined in an IETF context;

   o  the use of ARPA for purposes of operational infrastructure (and,
      by inference, the explicit non-use of a particular name in ARPA)
      is consistent with the purpose of that zone, as described in

   This document specifies that any request which would cause the name
   SINK.ARPA to exist in the DNS should be denied.

   Note that this document specifically does not recommend that the DNS
   name "SINK.ARPA" be treated differently from any other DNS name,
   operationally or in software.

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3.  Examples

   It is expected that the guaranteed non-existence of SINK.ARPA has
   many general operational applications.  What follows are two topical
   examples at the time of writing.  Note that these are speculative
   applications of the non-existence of SINK.ARPA, and would require
   more rigorous operational specification before they could be

   1.  Mail Transfer Agents (MTAs) which deliver mail using the SMTP
       protocol ([RFC5321]) look up MX records in order to identify the
       host to which SMTP connection attempts should be made.  For
       devices which do not support SMTP, it may be desirable to prevent
       MTAs from attempting any SMTP connection.  Installing an MX
       record whose RDATA includes SINK.ARPA in the EXCHANGE field
       ([RFC1034]) should cause compliant MTAs to make no connection:
       SINK.ARPA does not exist, and A and AAAA records should not be
       used when an MX record is present.

   2.  DNS UPDATE clients which send dynamic updates to DNS master
       servers ([RFC2136]) identify the primary master server for a zone
       using the MNAME field of the zone's SOA record ([RFC1034]).  The
       MNAME field is mandatory, but many zones intentionally do not
       accept dynamic updates.  DNS UPDATE messages for such zones may
       constitute unwanted traffic, and can be suppressed by specifying
       the MNAME to be SINK.ARPA.

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4.  IANA Considerations

   This document directs the IANA to create a registry as follows:

   | Parameter               | Value                                  |
   | Registry Name           | ARPA Reserved Names                    |
   |                         |                                        |
   | Reference               | This document (RFCXXXX) Section 5      |
   |                         |                                        |
   | Registration Procedures | IETF Standards Action and IAB approval |

   The initial registry contents should be as follows:

   | Name      | Purpose              | RRTypes | Reference            |
   | SINK.ARPA | Definitively         | NONE    | This document        |
   |           | non-existent name    |         | (RFCXXXX) Section 2  |

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5.  Administration of the ARPA Domain

   The management guidelines and operational requirements of the ARPA
   domain is described in [RFC3172].  Requests to modify the ARPA zone
   are specified in standards-track documents which, when approved by
   the IESG and the IAB are sent to the IANA for implementation.  This
   document updates the procedures described in that document as

5.1.  Criteria for "arpa" Sub-domains

   Names which are included in the IANA registry "ARPA Reserved Names"
   are reserved and require special consideration.  The nature of that
   special consideration is specified by reference within the ARPA
   Reserved Names registry.

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6.  IAB Considerations

   IAB review and approval of this document is required, given the IAB's
   technical and administrative function in the approval of changes to
   the ARPA zone.

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7.  Security Considerations

   This document institutionalises a single name in the DNS to which
   unwanted traffic can be directed.  This name, SINK.ARPA, is specified
   in this document not to exist in the DNS.  If address records for
   SINK.ARPA were to be introduced by exploiting insecurities in the
   DNS, however, then those addresses would receive that unwanted
   traffic.  This might provide a leak of private information to a third
   party, or have other unwelcome consequences.

   The non-existence of SINK.ARPA will be cryptographically verifiable
   when the ARPA zone is signed.

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8.  References

8.1.  Normative References

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, November 1987.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.

   [RFC2606]  Eastlake, D. and A. Panitz, "Reserved Top Level DNS
              Names", BCP 32, RFC 2606, June 1999.

   [RFC3172]  Huston, G., "Management Guidelines & Operational
              Requirements for the Address and Routing Parameter Area
              Domain ("arpa")", BCP 52, RFC 3172, September 2001.

8.2.  Informative References

   [RFC2136]  Vixie, P., Thomson, S., Rekhter, Y., and J. Bound,
              "Dynamic Updates in the Domain Name System (DNS UPDATE)",
              RFC 2136, April 1997.

   [RFC5321]  Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
              October 2008.

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Appendix A.  Editorial Notes

   This section (and sub-sections) to be removed prior to publication.

A.1.  On the name SINK.ARPA

   The name SINK.ARPA has been chosen as an editorial convenience:
   having a name is more convenient than not having a name when
   discussing the general proposal.  No doubt other names would do the
   job just as well.

A.2.  Change History

   00 Initial draft.

   01 Updated following feedback from Alfred Hoenes.

   02 Updated following feedback from Ralph Droms.

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Authors' Addresses

   Joe Abley
   4676 Admiralty Way, Suite 330
   Marina del Rey, CA  90292

   Phone: +1 310 301 3885

   Olafur Gudmundsson
   Shinkuro Inc.
   4922 Fairmont Avenue, Suite 250
   Bethesda, MD  20814


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