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Versions: (RFC 2606) 00

Network Working Group                                          L. Chapin
Internet-Draft                                Interisle Consulting Group
Intended status: Standards Track                             M. McFadden
Expires: December 2, 2011                                            ICC
                                                            May 31, 2011


                    Reserved Top Level Domain Names
                     draft-chapin-rfc2606bis-00.txt

Abstract

   The Internet Domain Name System (DNS) defines a tree of names
   starting with root, ".", immediately below which are top level domain
   (TLD) names such as ".com" and ".us".  RFC2606 reserved a small
   number of TLD names for use in documentation examples, private
   testing, experiments, and other circumstances in which it is
   desirable to avoid conflict with current or future actual TLD names
   in the DNS.  The evolution of Internet engineering and operation
   practices since RFC2606 was published in 1999, and the expected
   addition of new TLD names to the DNS, recommend this update to the
   list of reserved TLD names, and the creation of a "reserved TLD name
   registry" to which additional names may be added as new requirements
   arise.

   It is important to note that TLD names may be reserved, in other
   contexts, for policy, political, or other reasons that are distinct
   from the IETF's concern with Internet engineering and operations.
   This document reserves TLD names only for operational and engineering
   reasons.

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 December 2, 2011.




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Copyright Notice

   Copyright (c) 2011 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
   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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Legacy Reserved Top Level Domain Names . . . . . . . . . . . .  4
   3.  Additional Reserved Top Level Domain Names and Reserved
       TLD Name Registry  . . . . . . . . . . . . . . . . . . . . . .  5
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . .  7
   5.  IAB Considerations . . . . . . . . . . . . . . . . . . . . . .  8
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
   8.  Appendix - Initial Registry of Reserved Top Level Domain
       Names  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   9.  Normative References . . . . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13





















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1.  Introduction

   The Internet Domain Name System is documented in RFC1034 [1], RFC1035
   [2], RFC1591 [3] and numerous additional Requests for Comment.  It
   defines a tree of names starting with root, ".", immediately below
   which are top level domain names such as ".com" and ".us".  Below top
   level domain names there are normally additional levels of names.

   RFC2606 [5] reserved a small number of TLD names which, without fear
   of conflicts with current or future actual top level domain names in
   the global DNS, can be used for private testing of existing DNS
   related code, examples in documentation, DNS related experimentation,
   invalid DNS names, or other similar uses.  RFC2606 [5] also noted
   that the Internet Assigned Numbers Authority (IANA) reserves the
   label "example" at the second level below the TLDs .com, .net, and
   .org.

   Since RFC2606 [5] was published in 1999, Internet engineering and
   operation practices have evolved in ways that recommend this update
   to the list of reserved TLD names, and the creation of a "reserved
   TLD name registry" to which additional labels may be added as new
   requirements arise.  This update is also prompted by the expected
   advent of new TLDs which might, in the absence of the reservations
   for which this document provides, introduce TLD labels that could
   create engineering and operational problems for root server operators
   and other DNS infrastructure providers.

   It is important to note that TLD names may be reserved, in other
   contexts, for policy, political, or other reasons that are distinct
   from the IETF's concern with Internet engineering and operations.
   This document reserves TLD names only for operational and engineering
   reasons.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [4].















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2.  Legacy Reserved Top Level Domain Names

   The four top level domain name labels reserved by RFC2606 [5] for
   testing and documentation examples remain reserved:

   o  test

   o  example

   o  invalid

   o  localhost

   ".test" is recommended for use in testing of current or new DNS
   related code.

   ".example" is recommended for use in documentation or as examples.

   ".invalid" is intended for use in online construction of domain names
   that are sure to be invalid and which it is obvious at a glance are
   invalid.

   The ".localhost" TLD has traditionally been statically defined in
   host DNS implementations as having an A record pointing to the loop
   back IP address and is reserved for such use.  Any other use would
   conflict with widely deployed code which assumes this use.

   This document makes no changes to the IANA reservation of the label
   "example" at the second level.






















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3.  Additional Reserved Top Level Domain Names and Reserved TLD Name
    Registry

   In its report of a quantitative study of queries to the DNS root
   servers entitled "Invalid Top Level Domain Queries at the Root Level
   of the Domain Name System" [7] [or, SAC 045] ICANN's Security and
   Stability Advisory Committee "calls attention to the potential
   problems that may arise should a new TLD applicant use a string that
   has been seen with measurable (and meaningful) frequency in a query
   for resolution by the root system and the root system has previously
   generated a response."

   Of particular concern is the case in which a string "has been queried
   and a root name server has responded to the query with a non-existent
   domain (NXDOMAIN) result, i.e., the string has not been delegated but
   has been queried."  SAC 045 reports the results of a CAIDA
   measurement study [8] which found that "NXDOMAIN responses account
   for more than 25 percent of the total responses from root name
   servers observed in the study, and the top ten such strings account
   for 10 percent of the total query load."

   SAC 045 [7] describes in detail the engineering and operational
   problems that would ensue from the delegation, as new valid TLD
   names, of previously invalid labels that have frequently appeared in
   queries to the root: "If the [new TLD label] were to be approved and
   the TLD included in the root zone, queries to the root level of the
   DNS for a string that hitherto returned NXDOMAIN would begin to
   return positive responses containing name servers of the new TLD."

   Recommendation (2) of SAC 045 [7] calls for the community to develop
   principles for "prohibiting the delegation of additional strings to
   those already identified in RFC2606 [5]."  As the first step in that
   process, based on the data reported by SAC 045 [7], this document
   adds to the list of names that may not be used for top-level domains
   the following labels:

      .local

      .localdomain

      .domain

      .lan

      .home

      .host




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      .corp

   To facilitate the further steps that may be taken to pursue
   Recommendation (2) of SAC 045 [7], IANA is requested to publish a new
   registry of TLD names reserved by the IETF.  This Reserved TLD Name
   Registry should simply list the reserved TLD names with a reference
   in each case to the authority for reserving the name.  New names may
   be added to the registry through "IETF Specification Required" as
   provided by RFC4234 [6].  The initial contents of the registry are
   the names listed in Appendix A of this document.









































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4.  Security Considerations

   One of the reasons cited in Section 1 for reserving specific labels
   that cannot be used for valid top level domain names in the global
   DNS is to make it possible for those labels to be used safely in
   other contexts, without risk of conflict with "real" domain names.
   Reserving these labels therefore effectively encourages their use in
   locally-defined domain names that may resolve differently in
   different local contexts.  An application that looks up "foo.local"
   on private network A, for example, may get a different result if it
   looks up "foo.local" on private network B.

   A name that resolves differently depending on where the lookup
   request is made presents obvious security issues for any application
   that does not expect this behavior.  These issues arise from the use
   of any locally-defined labels in domain names, whether or not they
   are reserved.


































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5.  IAB Considerations

   There are no architectural implications related to reserving
   individual strings at the top level of the DNS.















































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6.  IANA Considerations

   According to RFC2606 [5], IANA agreed to the top level domain
   reservations in that document.  However, IANA was not instructed to
   publish a list of reserved names.

   IANA is requested to publish a new registry of TLD strings reserved
   by the IETF.  The Reserved TLD Name registry will consist of a list
   of reserved TLD names and a reference for each entry to the document
   that put the strings into reserved status.

   New strings are to be added to the registry through "IETF
   Specification Required" as provided by RFC4234 [6].  The initial
   content of the full registry is located in the Appendix to this
   document.




































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7.  Acknowledgements

   Several studies have shown that a large fraction of the lookup
   queries seen by the DNS root servers request information about
   invalid TLDs.  THe authors thank CAIDA, and in particular kc claffy,
   for their work in this area.  The authors are also indebted to the
   contributors to SAC 045 which provided the impetus for this first
   step at identifying a particular set of strings to be reserved.
   David Conrad provided helpful input about potential security concerns
   surrounding the reservation of strings at the root.









































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8.  Appendix - Initial Registry of Reserved Top Level Domain Names

   This is the initial registration for the registry of Reserved Top
   Level Names in the DNS.  The IANA is asked to use this material as
   guidance for the creation of the initial registry.  Future
   registrations in this registry will be done through "IETF
   Specification Required" as provided by RFC4234 [6].

                     +--------------+----------------+
                     |     Label    |    Reference   |
                     +--------------+----------------+
                     |     .corp    |     RFCxxx     |
                     |              |                |
                     |    .domain   |     RFCxxx     |
                     |              |                |
                     |   .example   | RFC2606,RFCxxx |
                     |              |                |
                     |     .home    |     RFCxxx     |
                     |              |                |
                     |     .host    |     RFCxxx     |
                     |              |                |
                     |   .invalid   | RFC2606,RFCxxx |
                     |              |                |
                     |     .lan     |     RFCxxx     |
                     |              |                |
                     |    .local    |     RFCxxx     |
                     |              |                |
                     | .localdomain |     RFCxxx     |
                     |              |                |
                     |   localhost  | RFC2606,RFCxxx |
                     |              |                |
                     |     test     | RFC2606,RFCxxx |
                     +--------------+----------------+

     NOTE TO RFC EDITOR: The correct number of this document should be
    substituted in the table above upon publication.  At that time this
                      editing note should be deleted.

                                  Table 1












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9.  Normative References

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

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

   [3]  Postel, J., "Domain Name System Structure and Delegation",
        RFC 1591, March 1994.

   [4]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

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

   [6]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
        Specifications: ABNF", RFC 4234, October 2005.

   [7]  <http://www.icann.org/en/committees/security/sac045.pdf>

   [8]  <http://www.caida.org/publications/presentations/2009/rssac_dns/
        rssac_dns.pdf>



























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Authors' Addresses

   Lyman Chapin
   Interisle Consulting Group

   Phone: +1 617 686 2527
   Email: lyman@interisle.net
   URI:   http://www.interisle.net


   Mark McFadden
   InterConnect Communications Ltd
   Merlin House
   Station Road
   Chepstow  NP16 5PB
   UK

   Phone: +1 608 628 2674
   Email: markmcfadden@icc-uk.com
   URI:   http://www.icc-uk.com































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