Dynamic Delegation Discovery System (DDDS) Part Three: The Domain Name System (DNS) Database
RFC 3403

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Network Working Group                                        M. Mealling
Request for Comments: 3403                                      VeriSign
Obsoletes: 2915, 2168                                       October 2002
Category: Standards Track

              Dynamic Delegation Discovery System (DDDS)
           Part Three: The Domain Name System (DNS) Database

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document describes a Dynamic Delegation Discovery System (DDDS)
   Database using the Domain Name System (DNS) as a distributed database
   of Rules.  The Keys are domain-names and the Rules are encoded using
   the Naming Authority Pointer (NAPTR) Resource Record (RR).

   Since this document obsoletes RFC 2915, it is the official
   specification for the NAPTR DNS Resource Record.  It is also part of
   a series that is completely specified in "Dynamic Delegation
   Discovery System (DDDS) Part One: The Comprehensive DDDS" (RFC 3401).
   It is very important to note that it is impossible to read and
   understand any document in this series without reading the others.

Mealling                    Standards Track                     [Page 1]
RFC 3403                   DDDS DNS Database                October 2002

Table of Contents

   1.    Introduction . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.    Terminology  . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.    DDDS Database Specification  . . . . . . . . . . . . . . . .  3
   4.    NAPTR RR Format  . . . . . . . . . . . . . . . . . . . . . .  5
   4.1   Packet Format  . . . . . . . . . . . . . . . . . . . . . . .  5
   4.2   Additional Information Processing  . . . . . . . . . . . . .  7
   4.2.1 Additional Section processing by DNS servers . . . . . . . .  7
   4.2.2 Additional Section processing by resolver/applications . . .  7
   4.3   Master File Format . . . . . . . . . . . . . . . . . . . . .  7
   5.    Application Specifications . . . . . . . . . . . . . . . . .  8
   6.    Examples . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   6.1   URN Example  . . . . . . . . . . . . . . . . . . . . . . . .  8
   6.2   E164 Example . . . . . . . . . . . . . . . . . . . . . . . . 10
   7.    Advice for DNS Administrators  . . . . . . . . . . . . . . . 10
   8.    Notes  . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   9.    IANA Considerations  . . . . . . . . . . . . . . . . . . . . 11
   10.   Security Considerations  . . . . . . . . . . . . . . . . . . 11
         References . . . . . . . . . . . . . . . . . . . . . . . . . 12
         Author's Address . . . . . . . . . . . . . . . . . . . . . . 13
         Full Copyright Statement . . . . . . . . . . . . . . . . . . 14

1. Introduction

   The Dynamic Delegation Discovery System (DDDS) is used to implement
   lazy binding of strings to data, in order to support dynamically
   configured delegation systems.  The DDDS functions by mapping some
   unique string to data stored within a DDDS Database by iteratively
   applying string transformation rules until a terminal condition is
   reached.

   This document describes the way in which the Domain Name System (DNS)
   is used as a data store for the Rules that allow a DDDS Application
   to function.  It does not specify any particular application or usage
   scenario.  The entire series of documents is specified in "Dynamic
   Delegation Discovery System (DDDS) Part One: The Comprehensive DDDS"
   (RFC 3401) [1].  It is very important to note that it is impossible
   to read and understand any document in that series without reading
   the related documents.

   The Naming Authority Pointer (NAPTR) DNS Resource Record (RR)
   specified here was originally produced by the URN Working Group as a
   way to encode rule-sets in DNS so that the delegated sections of a
   Uniform Resource Identifiers (URI) could be decomposed in such a way
   that they could be changed and re-delegated over time.  The result
   was a Resource Record that included a regular expression that would
   be used by a client program to rewrite a string into a domain name.

Mealling                    Standards Track                     [Page 2]
RFC 3403                   DDDS DNS Database                October 2002

   Regular expressions were chosen for their compactness to expressivity
   ratio allowing for a great deal of information to be encoded in a
   rather small DNS packet.

   Over time this process was generalized for other Applications and
   Rule Databases.  This document defines a Rules Database absent any