Principles for Unicode Code Point Inclusion in Labels in the DNS
draft-iab-dns-zone-codepoint-pples-00

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Network Working Group                                        A. Sullivan
Internet-Draft                                                 Dyn, Inc.
Intended status: Informational                                 D. Thaler
Expires: December 14, 2012                                     Microsoft
                                                              J. Klensin

                                                              O. Kolkman
                                                              NLnet Labs
                                                           June 12, 2012

    Principles for Unicode Code Point Inclusion in Labels in the DNS
                 draft-iab-dns-zone-codepoint-pples-00

Abstract

   IDNA makes available to DNS zone administrators a very wide range of
   Unicode code points.  Most operators of zones should probably not
   permit registration of U-labels using the entire range.  This is
   especially true of zones that accept registrations from outside
   parties, including (and most importantly) the root.  It is
   unfortunately not possible to generate algorithms to determine
   whether a code point is intrinsically safe to permit.  This memo
   presents a set of principles that can be used to guide the decision
   of whether a Unicode code point may be wisely included in the
   repertoire of permissible code points in a U-label in a zone.

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
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 14, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Sullivan, et al.        Expires December 14, 2012               [Page 1]
Internet-Draft       DNS Zone Code Point Principles            June 2012

   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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Background . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Less-restrictive Rules Going Down the DNS Tree . . . . . .  5
   3.  Principles applicable to all zones . . . . . . . . . . . . . .  6
     3.1.  Longevity Principle  . . . . . . . . . . . . . . . . . . .  6
     3.2.  Usability Principle  . . . . . . . . . . . . . . . . . . .  6
   4.  Principles applicable to all public zones  . . . . . . . . . .  6
     4.1.  Conservatism Principle . . . . . . . . . . . . . . . . . .  6
     4.2.  Inclusion Principle  . . . . . . . . . . . . . . . . . . .  7
     4.3.  Simplicity Principle . . . . . . . . . . . . . . . . . . .  7
     4.4.  Predictability Principle . . . . . . . . . . . . . . . . .  7
     4.5.  Stability Principle  . . . . . . . . . . . . . . . . . . .  8
   5.  Principle specific to the root zone  . . . . . . . . . . . . .  8
     5.1.  Letter Principle . . . . . . . . . . . . . . . . . . . . .  8
   6.  Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   10. Informative References . . . . . . . . . . . . . . . . . . . .  9
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10

Sullivan, et al.        Expires December 14, 2012               [Page 2]
Internet-Draft       DNS Zone Code Point Principles            June 2012

1.  Introduction

   Operators of a DNS zone need to set policies around what Unicode code
   points are allowed in labels in that zone.  Typically there a number
   of important goals to consider when constructing such policies.
   These include, for instance, possible visual confusability between
   two labels, possible confusion between Fully-Qualified Domain Names
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