draft-ietf-dnsext-insensitive-06.txt

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   capitalization.

   Note that the order of insertion into a server database of the DNS
   name tree nodes that appear in a Master File is not defined so that
   the results of inconsistent capitalization in a Master File are
   unpredictable output capitalization.



5. Internationalized Domain Names

   A scheme has been adopted for "internationalized domain names" and
   "internationalized labels" as described in [RFC 3490, 3454, 3491, and
   3492]. It makes most of [UNICODE] available through a separate
   application level transformation from internationalized domain name
   to DNS domain name and from DNS domain name to internationalized
   domain name. Any case insensitivity that internationalized domain
   names and labels have varies depending on the script and is handled
   entirely as part of the transformation described in [RFC 3454] and
   [RFC 3491] which should be seen for further details.  This is not a
   part of the DNS as standardized in STD 13.





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6. Security Considerations

   The equivalence of certain DNS label types with case differences, as
   clarified in this document, can lead to security problems. For
   example, a user could be confused by believing two domain names
   differing only in case were actually different names.

   Furthermore, a domain name may be used in contexts other than the
   DNS.  It could be used as a case sensitive index into some data base
   or file system. Or it could be interpreted as binary data by some
   integrity or authentication code system. These problems can usually
   be handled by using a standardized or "canonical" form of the DNS
   ASCII type labels, that is, always mapping the ASCII letter value
   octets in ASCII labels to some specific pre-chosen case, either upper
   case or lower case. An example of a canonical form for domain names
   (and also a canonical ordering for them) appears in Section 6 of [RFC
   4034]. See also [RFC 3597].

   Finally, a non-DNS name may be stored into DNS with the false
   expectation that case will always be preserved. For example, although
   this would be quite rare, on a system with case sensitive email
   address local parts, an attempt to store two "RP" records that
   differed only in case would probably produce unexpected results that
   might have security implications. That is because the entire email
   address, including the possibly case sensitive local or left hand
   part, is encoded into a DNS name in a readable fashion where the case
   of some letters might be changed on output as described above.

























D. Eastlake 3rd                                                 [Page 8]


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Copyright and Disclaimer

   Copyright (C) The Internet Society (2005).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.


   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM 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.



Normative References

   [ASCII] - ANSI, "USA Standard Code for Information Interchange",
   X3.4, American National Standards Institute: New York, 1968.

   [RFC 1034, 1035] - See [STD 13].

   [RFC 1995] - M. Ohta, "Incremental Zone Transfer in DNS", August
   1996.

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

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

   [RFC 3007] - B. Wellington, "Secure Domain Name System (DNS) Dynamic
   Update", November 2000.

   [RFC 3597] - Andreas Gustafsson, "Handling of Unknown DNS RR Types",
   draft-ietf-dnsext-unknown-rrs-05.txt, March 2003.

   [RFC 4034} - Arends, R., Austein, R., Larson, M., Massey, D., and S.
   Rose, "Resource Records for the DNS Security Extensions", RFC 4034,
   March 2005.

   [STD 13]
       - P. Mockapetris, "Domain names - concepts and facilities", RFC
   1034, November 1987.
       - P. Mockapetris, "Domain names - implementation and
   specification", RFC 1035, November 1987.




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Informative References

   [ISO 8859-1] - International Standards Organization, Standard for
   Character Encodings, Latin-1.

   [ISO 8859-2] - International Standards Organization, Standard for
   Character Encodings, Latin-2.

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

   [RFC 2606] - D. Eastlake, A. Panitz, "Reserved Top Level DNS Names",
   June 1999.

   [RFC 2929] - D. Eastlake, E. Brunner-Williams, B. Manning, "Domain
   Name System (DNS) IANA Considerations", September 2000.

   [RFC 2671] - P. Vixie, "Extension mechanisms for DNS (EDNS0)", August
   1999.

   [RFC 2673] - M. Crawford, "Binary Labels in the Domain Name System",
   August 1999.

   [RFC 3092] - D. Eastlake 3rd, C. Manros, E. Raymond, "Etymology of
   Foo", 1 April 2001.

   [RFC 3363] - Bush, R., Durand, A., Fink, B., Gudmundsson, O., and T.
   Hain, "Representing Internet Protocol version 6 (IPv6) Addresses in
   the Domain Name System (DNS)", RFC 3363, August 2002.

   [RFC 3454] - P. Hoffman, M. Blanchet, "Preparation of
   Internationalized String ("stringprep")", December 2002.

   [RFC 3490] - P. Faltstrom, P. Hoffman, A. Costello,
   "Internationalizing Domain Names in Applications (IDNA)", March 2003.

   [RFC 3491] - P. Hoffman, M. Blanchet, "Nameprep: A Stringprep Profile
   for Internationalized Domain Names (IDN)", March 2003.

   [RFC 3492] - A. Costello, "Punycode: A Bootstring encoding of Unicode
   for Internationalized Domain Names in Applications (IDNA)", March
   2003.

   [UNICODE] - The Unicode Consortium, "The Unicode Standard",
   <http://www.unicode.org/unicode/standard/standard.html>.







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Changes Between Draft Version

   RFC Editor: The following summaries of changes between draft versions
   are to be removed before publication.



-02 to -03 Changes

   The following changes were made between draft version -02 and -03:

   1. Add internationalized domain name section and references.

   2. Change to indicate that later input of a label for an existing DNS
   name tree node may or may not be normalized to the earlier input or
   override it or both may be preserved.

   3. Numerous minor wording changes.



-03 to -04 Changes

   The following changes were made between draft versions -03 and -04:

   1. Change to conform to the new IPR, Copyright, etc., notice
   requirements.

   2. Change in some section headers for clarity.

   3. Drop section on wildcards.

   4. Add emphasis on loss of case preservation due to name compression.

   5. Add references to RFCs 1995 and 3092.



-04 to -05 Changes

   The following changes were made between draft versions -04 and -05:

   1. More clearly state that this draft updates RFCs 1034, 1035 [STD
   13].

   2. Add informative references to ISO 8859-1 and ISO 8859-2.

   3. Fix hyphenation and capitalization nits.




D. Eastlake 3rd                                                [Page 11]


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-05 to -06 Changes

   The following changes were made between draft version -05 and -06.

   1. Add notation to the RFC Editor that the draft version change
   summaries are to be removed before RFC publication.

   2. Additional text explaining why labe case insensitivity is CLASS
   independent.

   3. Changes and additional text clarifying that the fact that
   inconsistent case in data loaded into DNS may result in
   unpredicatable or inconsistent case in DNS storage but has no effect
   on the completeness of RR sets retrieved.

   4. Add reference to [RFC 3363] and update reference to [RFC 2535] to
   be to [RFC 4034].



































D. Eastlake 3rd                                                [Page 12]


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Author's Address

   Donald E. Eastlake 3rd
   Motorola Laboratories
   155 Beaver Street
   Milford, MA 01757 USA

   Telephone:   [phone] (w)

   EMail:       [e-mail]



Expiration and File Name

   This draft expires January 2006.

   Its file name is draft-ietf-dnsext-insensitive-06.txt.


































D. Eastlake 3rd                                                [Page 13]