RFC 2606

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Network Working Group D. Eastlake Request for Comments: 2606 A. Panitz BCP: 32 June 1999 Category: Best Current Practice


                     Reserved Top Level DNS Names

Status of this Memo

  This document specifies an Internet Best Current Practices for the
  Internet Community, and requests discussion and suggestions for
  improvements.  Distribution of this memo is unlimited.

Copyright Notice

  Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

  To reduce the likelihood of conflict and confusion, a few top level
  domain names are reserved for use in private testing, as examples in
  documentation, and the like.  In addition, a few second level domain
  names reserved for use as examples are documented.

Table of Contents

  1. Introduction............................................1
  2. TLDs for Testing, & Documentation Examples..............2
  3. Reserved Example Second Level Domain Names..............2
  4. IANA Considerations.....................................3
  5. Security Considerations.................................3
  References.................................................3
  Authors' Addresses.........................................4
  Full Copyright Statement...................................5

Introduction

  The global Internet Domain Name System is documented in [RFC 1034,
  1035, 1591] 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.

TLDs for Testing, & Documentation Examples

  There is a need for top level domain (TLD) names that can be used for
  creating names which, without fear of conflicts with current or
  future actual TLD 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.
  For example, without guidance, a site might set up some local
  additional unused top level domains for testing of its local DNS code
  and configuration. Later, these TLDs might come into actual use on
  the global Internet.  As a result, local attempts to reference the
  real data in these zones could be thwarted by the local test
  versions.  Or test or example code might be written that accesses a
  TLD that is in use with the thought that the test code would only be
  run in a restricted testbed net or the example never actually run.
  Later, the test code could escape from the testbed or the example be
  actually coded and run on the Internet. Depending on the nature of
  the test or example, it might be best for it to be referencing a TLD
  permanently reserved for such purposes.
  To safely satisfy these needs, four domain names are reserved as
  listed and described below.
                  .test
               .example
               .invalid
             .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.

Reserved Example Second Level Domain Names

  The Internet Assigned Numbers Authority (IANA) also currently has the
  following second level domain names reserved which can be used as
  examples.
       example.com
       example.net
       example.org

IANA Considerations

  IANA has agreed to the four top level domain name reservations
  specified in this document and will reserve them for the uses
  indicated.

Security Considerations

  Confusion and conflict can be caused by the use of a current or
  future top level domain name in experimentation or testing, as an
  example in documentation, to indicate invalid names, or as a synonym
  for the loop back address.  Test and experimental software can escape
  and end up being run against the global operational DNS.  Even
  examples used "only" in documentation can end up being coded and
  released or cause conflicts due to later real use and the possible
  acquisition of intellectual property rights in such "example" names.
  The reservation of several top level domain names for these purposes
  will minimize such confusion and conflict.

References

  [RFC 1034] Mockapetris, P., "Domain names - concepts and facilities",
             STD 13, RFC 1034, November 1987.
  [RFC 1035] Mockapetris, P., "Domain names - implementation and
             specification", STD 13, RFC 1035, November 1987.
  [RFC 1591] Postel, J., "Domain Name System Structure and Delegation",
             RFC 1591, March 1994.

Authors' Addresses

  Donald E. Eastlake 3rd
  IBM
  65 Shindegan Hill Road, RR #1
  Carmel, NY 10512
  Phone: +1 914-276-1668(h)
         +1 914-784-7913(w)
  FAX:   +1 914-784-3833(3)
  EMail: dee3@us.ibm.com


  Aliza R. Panitz
  500 Stamford Dr. No. 310
  Newark, DE 19711 USA
  Phone: +1 302-738-1554
  EMail: buglady@fuschia.net

Full Copyright Statement

  Copyright (C) The Internet Society (1999).  All Rights Reserved.
  This document and translations of it may be copied and furnished to
  others, and derivative works that comment on or otherwise explain it
  or assist in its implementation may be prepared, copied, published
  and distributed, in whole or in part, without restriction of any
  kind, provided that the above copyright notice and this paragraph are
  included on all such copies and derivative works.  However, this
  document itself may not be modified in any way, such as by removing
  the copyright notice or references to the Internet Society or other
  Internet organizations, except as needed for the purpose of
  developing Internet standards in which case the procedures for
  copyrights defined in the Internet Standards process must be
  followed, or as required to translate it into languages other than
  English.
  The limited permissions granted above are perpetual and will not be
  revoked by the Internet Society or its successors or assigns.
  This document and the information contained herein is provided on an
  "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
  TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
  BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
  HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
  MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

  Funding for the RFC Editor function is currently provided by the
  Internet Society.

Eastlake & Panitz Best Current Practice [Page 5]