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Network Working GroupF. Ellermann
Internet-Draftxyzzy
Obsoletes: 2606 (if approved)D. Eastlake
Intended status: BCPEastlake Enterprises
Expires: January 4, 2009July 03, 2008


Reserved Top Level DNS Names
draft-ellermann-idnabis-test-tlds-08

Status of this Memo

By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79.

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This Internet-Draft will expire on January 4, 2009.

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. This memo replaces RFC 2606.

Editorial note

This note and the document history (Document History) should be removed before publication. The draft can be discussed on the IETF Discussion <ietf.ietf.org> mailing list.



Table of Contents

1.  Introduction
2.  TLDs for Testing, & Documentation Examples
    2.1.  ".example"
    2.2.  ".invalid"
    2.3.  ".localhost"
    2.4.  ".test"
3.  Reserved Example Second Level Domain Names
4.  Internationalization Considerations
5.  IANA Considerations
6.  Security Considerations
7.  Acknowledgments
8.  References
    8.1.  Normative References
    8.2.  Informative References
Appendix A.  Educational Info
Appendix B.  Document History
§  Authors' Addresses
§  Intellectual Property and Copyright Statements




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1.  Introduction

The global Internet Domain Name System is documented in [RFC1034] (Mockapetris, P., “Domain names - concepts and facilities,” November 1987.), [RFC1035] (Mockapetris, P., “Domain names - implementation and specification,” November 1987.), [RFC1123] (Braden, R., “Requirements for Internet Hosts - Application and Support,” October 1989.), [RFC1591] (Postel, J., “Domain Name System Structure and Delegation,” March 1994.), and numerous additional Requests for Comments. 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.

IPv4 addresses used for tests and in examples are specified in [I‑D.iana‑rfc3330bis] (Cotton, M. and L. Vegoda, “Special Use IPv4 Addresses,” August 2009.), IPv6 addresses used in examples are described in [RFC3849] (Huston, G., Lord, A., and P. Smith, “IPv6 Address Prefix Reserved for Documentation,” July 2004.); see also [RFC4085] (Plonka, D., “Embedding Globally-Routable Internet Addresses Considered Harmful,” June 2005.).

Fully Qualified Domain Names used in many Internet Protocols allow only LDH (letter, digit, hyphen) domain labels as described in [RFC1123] (Braden, R., “Requirements for Internet Hosts - Application and Support,” October 1989.) and [RFC4343] (Eastlake, D., “Domain Name System (DNS) Case Insensitivity Clarification,” January 2006.). The letters are ASCII letters; LDH-labels are also known as A-labels in the context of IDN (Internationalization of Domain Names) and [IDNAbis] (IETF, “Internationalized Domain Names in Applications (Revised),” April 2008.).

The key words "MAY", "RECOMMENDED", and "SHOULD" in this memo are to be interpreted as described in [RFC2119] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).



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2.  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. See also Section 4 (Internationalization Considerations).



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2.1.  ".example"

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



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2.2.  ".invalid"

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

Applications MAY treat ".invalid" as what the name says. For this technical reason reserving internationalized ".invalid" TLDs would be unwise.



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2.3.  ".localhost"

The ".localhost" TLD has traditionally been statically defined in host DNS implementations as having an address 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.

See [RFC1122] (Braden, R., “Requirements for Internet Hosts - Communication Layers,” October 1989.) for IPv4 and [RFC4291] (Hinden, R. and S. Deering, “IP Version 6 Addressing Architecture,” February 2006.) for IPv6 loop back addresses.



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2.4.  ".test"

".test" and the new test TLDs in Section 4 (Internationalization Considerations) are RECOMMENDED for use in testing of current or new DNS related code. Applications SHOULD treat these test TLDs like any other TLD; a special handling could defeat the purpose of a test.



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3.  Reserved Example Second Level Domain Names

The Internet Assigned Numbers Authority (IANA) also reserves the three second level domain names ".example.com", ".example.net", and ".example.org", which can be used in examples as explained in Section 2.1 (".example").

When TLDs offer further second level domains for examples, the TLD administrators are encouraged to publish the relevant policies in their TLD as an informational RFC.

The second level domain names "nic", "whois", and "www" are often reserved or used for administrative purposes of the TLD, e.g., "whois.example" for the fully qualified domain name of a host with a whois server. As with second level domains for examples this can be an issue in the case of a TLD redelegation.

Please note that there are no globally reserved LDH DNS labels below the top level, see [RFC4367] (Rosenberg, J. and IAB, “What's in a Name: False Assumptions about DNS Names,” February 2006.).



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4.  Internationalization Considerations

In 2007 IANA created eleven IDN test TLDs. The A-labels, corresponding languages, and IDN U-labels are listed below; see [RFC3490] (Faltstrom, P., Hoffman, P., and A. Costello, “Internationalizing Domain Names in Applications (IDNA),” March 2003.) or its [IDNAbis] (IETF, “Internationalized Domain Names in Applications (Revised),” April 2008.) successor for details about IDN. Applications SHOULD treat these IDN test TLDs as explained in Section 2.4 (".test").

      TLD A-label         Language            U-label (hex. code points)
    ".xn--0zwm56d"        Chinese (simplified)                 6d4b 8bd5
    ".xn--11b5bs3a9aj6g"  Hindi              92a 930 940 915 94d 937 93e
    ".xn--80akhbyknj4f"   Russian    438 441 43f 44b 442 430 43d 438 435
    ".xn--9t4b11yi5a"     Korean                          d14c c2a4 d2b8
    ".xn--deba0ad"        Yiddish                        5d8 5e2 5e1 5d8
    ".xn--g6w251d"        Chinese (traditional)                6e2c 8a66
    ".xn--hgbk6aj7f53bba" Persian            622 632 645 627 6cc 634 6cc
    ".xn--hlcj6aya9esc7a" Tamil              baa bb0 bbf b9f bcd b9a bc8
    ".xn--jxalpdlp"       Greek                  3b4 3bf 3ba 3b9 3bc 3ae
    ".xn--kgbechtv"       Arabic                 625 62e 62a 628 627 631
    ".xn--zckzah"         Japanese                        30c6 30b9 30c8


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5.  IANA Considerations

IANA reserves the TLDs ".example", ".invalid", ".localhost", ".test", and eleven IDN test TLDs as noted above. IANA reserves the second level domains ".example.com", ".example.net", and ".example.org".

IANA creates a registry of reserved TLDs; this can be done alongside existing IANA TLD registries at the discretion of IANA. The registry should contain references to the relevant specifications, for the fifteen reserved TLDs specified here references to this memo will do.

Additional reserved TLDs require IETF review as defined in [RFC5226] (Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” May 2008.) section 4.1 in conjunction with [RFC2860] (Carpenter, B., Baker, F., and M. Roberts, “Memorandum of Understanding Concerning the Technical Work of the Internet Assigned Numbers Authority,” June 2000.) section 4.3.

The technical purpose of a reserved TLD has to be stated in its specification.

Proposals to reserve TLD labels not permitted for ordinary TLDs, as specified in [RFC1123] (Braden, R., “Requirements for Internet Hosts - Application and Support,” October 1989.) among others, e.g., labels not starting with a letter, or not following known LDH-rules, are not expected to survive IETF review without compelling reasons.



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6.  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 minimizes such confusion and conflict.

[RFC4367] (Rosenberg, J. and IAB, “What's in a Name: False Assumptions about DNS Names,” February 2006.) discusses various false assumptions based on domain labels, however this doesn't affect the reserved TLDs in this memo.

Readers need to be aware that the IANA registry of reserved TLDs in Section 5 (IANA Considerations) won't list all reserved TLDs for specific applications and protocols. The registry can only list reserved TLDs if somebody bothered to propose it, typically in an Internet-Draft, and the proposal was accepted in an IETF review.



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7.  Acknowledgments

This memo contains major parts of [RFC2606] (Eastlake, D. and A. Panitz, “Reserved Top Level DNS Names,” June 1999.) written by Donald E. Eastlake and Aliza R. Panitz.

Thanks to Alfred Hönes, Brian Carpenter, Dave Cridland, David Conrad, Debbie Garside, Doug Otis, Joe Abley, John Klensin, John Levine, Lyman Chapin, Marcel Parodi, Mark Andrews, Marshall Eubanks, Ole Jacobsen, Paul Hoffman, Philip Guenther, Philip Hallam-Baker, SM, Steve Crocker, Sumit Pandya, Thomas Narten, Tina Dam, Tony Finch, and Tony Hansen for their feedback, contributions, or encouragement.



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8.  References



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8.1. Normative References

[RFC2119] Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” BCP 14, RFC 2119, March 1997 (TXT, HTML, XML).
[RFC2860] Carpenter, B., Baker, F., and M. Roberts, “Memorandum of Understanding Concerning the Technical Work of the Internet Assigned Numbers Authority,” RFC 2860, June 2000 (TXT).
[RFC5226] Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” BCP 26, RFC 5226, May 2008 (TXT).


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8.2. Informative References

[RFC1034] Mockapetris, P., “Domain names - concepts and facilities,” STD 13, RFC 1034, November 1987 (TXT).
[RFC1035] Mockapetris, P., “Domain names - implementation and specification,” STD 13, RFC 1035, November 1987 (TXT).
[RFC1122] Braden, R., “Requirements for Internet Hosts - Communication Layers,” STD 3, RFC 1122, October 1989 (TXT).
[RFC1123] Braden, R., “Requirements for Internet Hosts - Application and Support,” STD 3, RFC 1123, October 1989 (TXT).
[RFC1591] Postel, J., “Domain Name System Structure and Delegation,” RFC 1591, March 1994 (TXT).
[RFC2606] Eastlake, D. and A. Panitz, “Reserved Top Level DNS Names,” BCP 32, RFC 2606, June 1999 (TXT).
[RFC2965] Kristol, D. and L. Montulli, “HTTP State Management Mechanism,” RFC 2965, October 2000 (TXT, HTML, XML).
[RFC3490] Faltstrom, P., Hoffman, P., and A. Costello, “Internationalizing Domain Names in Applications (IDNA),” RFC 3490, March 2003 (TXT).
[RFC3849] Huston, G., Lord, A., and P. Smith, “IPv6 Address Prefix Reserved for Documentation,” RFC 3849, July 2004 (TXT).
[RFC3927] Cheshire, S., Aboba, B., and E. Guttman, “Dynamic Configuration of IPv4 Link-Local Addresses,” RFC 3927, May 2005 (TXT).
[RFC4085] Plonka, D., “Embedding Globally-Routable Internet Addresses Considered Harmful,” BCP 105, RFC 4085, June 2005 (TXT).
[RFC4291] Hinden, R. and S. Deering, “IP Version 6 Addressing Architecture,” RFC 4291, February 2006 (TXT).
[RFC4343] Eastlake, D., “Domain Name System (DNS) Case Insensitivity Clarification,” RFC 4343, January 2006 (TXT).
[RFC4367] Rosenberg, J. and IAB, “What's in a Name: False Assumptions about DNS Names,” RFC 4367, February 2006 (TXT).
[I-D.iana-rfc3330bis] Cotton, M. and L. Vegoda, “Special Use IPv4 Addresses,” draft-iana-rfc3330bis-11 (work in progress), August 2009 (TXT).
[IDNAbis] IETF, “Internationalized Domain Names in Applications (Revised),” April 2008.


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Appendix A.  Educational Info

This informative appendix tries to answer three frequently asked questions:

  1. As of 2008 IANA is the registrant of ".example.edu"; TLD ".edu" has no contract with ICANN; its administration is based on a five years contract with the US DoC renewed in 2006; see http://net.educause.edu/edudomain/policy.asp. Under amendment 6 of their current policy generic names cannot be registered. This is not exactly the same situation as for say ".example.org", where IANA is the registrant and registrar.
  2. As of 2008 IANA is the registrant of ".example.info"; TLD ".info" was created by ICANN in 2001. The ".info" registry agreement lists reserved DNS labels including "example"; see http://www.icann.org/tlds/agreements/info/ appendix 6 (2006) and K (2001), respectively. This is not exactly the same situation as for say ".example.org", where IANA is the registrant and registrar.
  3. Ignoring [RFC2965] (Kristol, D. and L. Montulli, “HTTP State Management Mechanism,” October 2000.) the TLD ".local" issue was discussed in a bunch of Internet-Drafts related to AS112, zeroconf, and [RFC3927] (Cheshire, S., Aboba, B., and E. Guttman, “Dynamic Configuration of IPv4 Link-Local Addresses,” May 2005.). Presumably TLD ".local" should be registered as reserved for technical reasons, but deserves its own document with the fine print.


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Appendix B.  Document History

Changes in version 08:

Changes in version 07:

Changes in version 06:

Changes in version 05:

Changes in version 04:

Changes in version 03:

Changes in version 02:

Changes in version 01:

Changes in version 00:



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Authors' Addresses

  Frank Ellermann
  xyzzy
  Hamburg, Germany
Email:  hmdmhdfmhdjmzdtjmzdtzktdkztdjz@gmail.com
URI:  http://purl.net/xyzzy/
  
  Donald E. Eastlake 3rd
  Eastlake Enterprises
  155 Beaver Street
  Milford, MA 01757
  USA
Phone:  +1-508-634-2066
Email:  d3e3e3@gmail.com


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Full Copyright Statement

Intellectual Property

Acknowledgment