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rfc:rfc3405

Network Working Group M. Mealling Request for Comments: 3405 VeriSign BCP: 65 October 2002 Category: Best Current Practice

   Dynamic Delegation Discovery System (DDDS) Part Five: URI.ARPA
                       Assignment Procedures

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 (2002).  All Rights Reserved.

Abstract

 This document is fifth in 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.

Table of Contents

 1.    Introduction . . . . . . . . . . . . . . . . . . . . . . . .  2
 2.    URI Resolution vs URN Resolution . . . . . . . . . . . . . .  2
 3.    Registration Policies  . . . . . . . . . . . . . . . . . . .  3
 3.1   URI.ARPA Registration  . . . . . . . . . . . . . . . . . . .  3
 3.1.1 Only Schemes in the IETF Tree Allowed  . . . . . . . . . . .  3
 3.1.2 Scheme Registration Takes Precedence . . . . . . . . . . . .  3
 3.1.3 NAPTR Registration May Accompany Scheme Registration . . . .  3
 3.1.4 Registration or Changes after Scheme Registration  . . . . .  3
 3.2   URN.ARPA Registration  . . . . . . . . . . . . . . . . . . .  4
 3.2.1 NID Registration Takes Precedence  . . . . . . . . . . . . .  4
 3.2.2 NAPTR Registration May Accompany NID Registration  . . . . .  4
 3.2.3 Registration or Changes after Scheme Registration  . . . . .  4
 4.    Requirements on hints  . . . . . . . . . . . . . . . . . . .  4
 5.    Submission Procedure . . . . . . . . . . . . . . . . . . . .  5
 6.    Registration Template  . . . . . . . . . . . . . . . . . . .  6
 6.1   Key  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
 6.2   Authority  . . . . . . . . . . . . . . . . . . . . . . . . .  6
 6.3   Records  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
 7.    Example Template . . . . . . . . . . . . . . . . . . . . . .  6

Mealling Best Current Practice [Page 1] RFC 3405 DDDS URI.ARPA Assignment Procedures October 2002

 8.    The URN Registration in the URI.ARPA zone  . . . . . . . . .  7
 9.    IANA Considerations  . . . . . . . . . . . . . . . . . . . .  7
 10.   Security Considerations  . . . . . . . . . . . . . . . . . .  7
 11.   Acknowledgements . . . . . . . . . . . . . . . . . . . . . .  7
 12.   References . . . . . . . . . . . . . . . . . . . . . . . . .  8
 13.   Author's Address . . . . . . . . . . . . . . . . . . . . . .  9
 14.   Full Copyright Statement . . . . . . . . . . . . . . . . . . 10

1. Introduction

 This document defines the policies and procedures for inserting
 Naming Authority Pointer (NAPTR) records into the 'URI.ARPA' and
 'URN.ARPA' zones for the purpose of resolving Uniform Resource
 Identifiers (URIs) according to "Dynamic Delegation Discovery System
 (DDDS) Part Four:  The URI Resolution Application" (RFC 3402) [2],
 which is an Application that uses the Domain Name System (DNS) based
 DDDS Database.  All of these concepts are defined in RFC 3401 [1].
 It is very important to note that it is impossible to correctly
 understand this document without reading RFC 3401 and the documents
 it specifies.
 RFC 3403 defines a how DNS is used as a DDDS database that contains
 URI delegation rules (sometimes called resolution hints).  That
 document specifies that the first step in that algorithm is to append
 'URI.ARPA' to the URI scheme and retrieve the NAPTR record for that
 domain-name.  I.e., the first step in resolving "http://foo.com/"
 would be to look up a NAPTR record for the domain "http.URI.ARPA".
 URN resolution also follows a similar procedure but uses the
 'URN.ARPA' zone as its root.  This document describes the procedures
 for inserting a new rule into the 'URI.ARPA' and 'URN.ARPA' zones.

2. URI Resolution vs URN Resolution

 RFC 3402 [2] defines how both URI [7] resolution and URN [6]
 resolution work when DNS is used as the delegation rule (or hint)
 database.  Specifically it says that the initial instructions
 ('hints') for DNS-based resolution of URIs are stored as resource
 records in the 'URI.ARPA' DNS zone.
 Since a URN is a URI scheme, a hint for resolution of the URI prefix
 'urn:' will also be stored in the 'URI.ARPA' zone.  This rule states
 that the namespace id [6] is extracted, 'URN.ARPA' is appended to the
 end of the namespace id, and the result is used as the key for
 retrieval of a subsequent NAPTR record [4].

Mealling Best Current Practice [Page 2] RFC 3405 DDDS URI.ARPA Assignment Procedures October 2002

3. Registration Policies

 The creation of a given URI scheme or URN namespace id (NID) follows
 the appropriate registration documents for those spaces.  URI schemes
 follow "Registration Procedures for URL Scheme Names" (RFC 2717)
 [10].  URN namespace ids follow "URN Namespace Definition Mechanisms"
 (RFC 2611) (or updates thereto) [9].

3.1 URI.ARPA Registration

3.1.1 Only Schemes in the IETF Tree Allowed

 In order to be inserted into the URI.ARPA zone, the subsequent URI
 scheme MUST be registered under the IETF URI tree.  The requirements
 for this tree are specified in [10].

3.1.2 Scheme Registration Takes Precedence

 The registration of a NAPTR record for a URI scheme MUST NOT precede
 proper registration of that scheme and publication of a stable
 specification in accordance with [10].  The IESG or its designated
 expert will review the request for
    1.  correctness and technical soundness
    2.  consistency with the published URI specification, and
    3.  to ensure that the NAPTR record for a DNS-based URI does not
        delegate resolution of the URI to a party other than the
        holder of the DNS name.  This last rule is to insure that a
        given URI's resolution hint doesn't hijack (inadvertently or
        otherwise) network traffic for a given domain.

3.1.3 NAPTR Registration May Accompany Scheme Registration

 A request for a URI.ARPA registration MAY accompany a request for a
 URI scheme (in accordance with [10]), in which case both requests
 will be reviewed simultaneously by IESG or its designated experts.

3.1.4 Registration or Changes after Scheme Registration

 A request for a NAPTR record (or an request to change an existing
 NAPTR record) MAY be submitted after the URI prefix has been
 registered.  If the specification for the URI prefix is controlled by
 some other party than IETF, IESG will require approval from the
 owner/maintainer of that specification before the registration will
 be accepted.  This is in addition to any technical review of the
 NAPTR registration done by IESG or its designated experts.

Mealling Best Current Practice [Page 3] RFC 3405 DDDS URI.ARPA Assignment Procedures October 2002

3.2 URN.ARPA Registration

3.2.1 NID Registration Takes Precedence

 The registration of a NAPTR record for a URN NID MUST NOT precede
 proper registration of that NID and publication of a stable
 specification in accordance with [9].  This is to prevent the
 registration of a NAPTR record in URN.ARPA from circumventing the NID
 registration process.

3.2.2 NAPTR Registration May Accompany NID Registration

 A request for a URN.ARPA registration MAY accompany a request for a
 NID (in accordance with [9]), in which case both requests will be
 reviewed at the same time.

3.2.3 Registration or Changes after Scheme Registration

 A request for a NAPTR record (or an request to change an existing
 NAPTR record) MAY be submitted after the NID has been registered.  If
 the specification for the NID is controlled by some other party than
 IETF, IESG will require approval from the owner/maintainer of that
 specification before the registration will be accepted.  This is in
 addition to any technical review of the NAPTR registration done by
 IESG or its designated experts.
 Note that this applies to all NAPTR records for a particular NID,
 even though a NAPTR record might affect only part of the URN space
 assigned to an NID

4. Requirements on hints

 Delegation of a namespace can happen in two ways.  In the case of
 most URIs, the key being delegated to is hard-coded into the
 identifier itself (e.g., a hostname in an HTTP URI).  The syntax of
 where this new key is located is predetermined by the syntax of the
 scheme.  In other cases, the new key can be part of the hint itself.
 This is the functional equivalent of saying, "if this rule matches
 then this is always the key."
 In order to minimize the query load on the URI.ARPA and URN.ARPA
 zones, it is anticipated that the resource records in those zones
 will have extremely long "times to live" (TTLs), perhaps measured in
 years.

Mealling Best Current Practice [Page 4] RFC 3405 DDDS URI.ARPA Assignment Procedures October 2002

 Thus, for any URI prefix or URN namespace for which the resolution
 hints are likely to change, the actual rule should be stored in some
 other (less stable) DNS zone, and within URI.ARPA or URN.ARPA a
 stable NAPTR record should be used to delegate queries to that less
 stable zone.
 For example, the 'foo' URN namespace has flexible rules for how
 delegation takes place.  Instead of putting those rules in the
 URN.ARPA zone, the entry instead punts those rules off to a
 nameserver that has a shorter time to live.  The record in URN.ARPA
 would look like this:
    foo     IN NAPTR 100 10  ""  "" "" urn-resolver.foo.com.
 Thus, when the client starts out in the resolution process, the first
 step will be to query foo.URN.ARPA to find the above record, the
 second step is to begin asking 'urn-resolver.foo.com' for the NAPTR
 records that contain the resolution rules.  The TTL at the root is
 very long.  The TTL at the 'urn-resolver.foo.com' is much shorter.
 Conversely, the 'http' URI scheme adheres to a particular syntax that
 specifies that the host to ask is specified in the URI in question.
 Since this syntax does not change, that rule can be specified in the
 URI.ARPA zone.  The record would look like this:
    http    IN NAPTR 100 100 "" ""  "/http:\\/\\/([^\\/:]+)/\\2/i" .
 Thus, the second step of resolution is to use the domain-name found
 in the URI as the next key in the cycle.  If, for example, that NAPTR
 was terminal and contains some hostname in the replacement field,
 then the client could contact that host in order to ask questions
 about this particular URI.

5. Submission Procedure

 Using the MIME Content-Type registration  mechanism [8] as a model
 for a successful registration mechanism, the 'URI.ARPA' and
 'URN.ARPA' procedures consist of a request template submitted to an
 open mailing list made up of interested parties.  If no objections
 are made within a two week period, a representative of the
 registration authority considers the submission to be accepted and
 enters that submission into the nameserver.
     o  Registrations for the 'URI.ARPA' zone are sent to
         'register@URI.ARPA'.

Mealling Best Current Practice [Page 5] RFC 3405 DDDS URI.ARPA Assignment Procedures October 2002

     o  Registrations for the 'URN.ARPA' zone are sent to
         'register@URN.ARPA'.
     The registration authority is the Internet Assigned Numbers
     Authority (IANA).
 Objections are restricted to those that point out impacts on the zone
 itself or to DNS in general.  Objections to the URI scheme or to the
 URN namespace-id are not allowed, as these should be raised in their
 respective forums.  The logical conclusion of this is that ANY
 sanctioned URI scheme or URN namespace MUST be allowed to be
 registered if it meets the requirements specified in this document as
 regards times to live and general impact to the DNS.

6. Registration Template

 The template to be sent to the appropriate list MUST contain the
 following values:

6.1 Key

 This is the URN NID or URI scheme, which is used as the domain
 portion of the DNS entry.  It must be valid according to the
 procedures specified in the URN namespace-id assignment document and
 any future standards for registering new URI schemes.

6.2 Authority

 This is the individual or organization (entity) which has authority
 for registering the record.  It must be an authority recognized as
 either the IESG or any authority defined in the URN NID [9] or URI
 scheme registration [10] documents.

6.3 Records

 The actual DNS records representing the rule set for the key.  The
 required values are Preference, Order, Flags, Services, Regex, and
 Replacement as defined by RFC 3404 [4].

7. Example Template

 To: register@URN.ARPA
 From: joe@foo.com
 Key: foo
 Authority: Foo Technology, Inc as specified in RFCFOO
 Record: foo     IN NAPTR 100 100 "" "" "" urn.foo.com.

Mealling Best Current Practice [Page 6] RFC 3405 DDDS URI.ARPA Assignment Procedures October 2002

8. The URN Registration in the URI.ARPA zone

 Since this document discusses the URI.ARPA and URN.ARPA zones and the
 URN rule that exists in the URI.ARPA zone, it makes sense for the
 registration template for the URN URI rule to be specified here:
       To: register@URI.ARPA
       From: The IETF URN Working Group
       Key: urn
       Authority: RFC2141
       Record: urn     IN NAPTR 0 0 "" "" "/^urn:([^:]+)/\\2/i" .

9. IANA Considerations

 The IANA has created the zones URN.ARPA and URI.ARPA.  The
 hierarchical name structure, and the only names to be assigned within
 these zones, are the "keys" as described in Section 6.1 of this
 document.  The administrative and operational management of these
 zones are to be undertaken by the IANA.  The DNS records to be
 inserted in these zones are subject to the review process described
 in this document.
 The IANA has also created two discussion lists, register@uri.arpa and
 register@urn.arpa, for the purposes described in this document.  The
 IANA will manage these mailing lists.

10. Security Considerations

 The 'uri.arpa' and 'urn.arpa' zones will be a common point of attack
 both for Denial of Service and for spoofing entries in order to
 redirect delegation paths.  Any entity running nameservers that
 contain these zones should take appropriate action for securing an
 infrastructure level component of the Internet.  When it becomes
 possible for a nameserver to reliably sign the records in its zone it
 should do so.

11. Acknowledgements

 The author would like to thank Ron Daniel who was originally co-
 author of these documents.  Ron's original insite into the intricate
 nature of delegation rules made these procedures and the DDDS itself
 possible.

Mealling Best Current Practice [Page 7] RFC 3405 DDDS URI.ARPA Assignment Procedures October 2002

12. References

 [1]   Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
       One: The Comprehensive DDDS", RFC 3401, October 2002.
 [2]   Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
       Two: The Algorithm", RFC 3402, October 2002.
 [3]   Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
       Three: The Domain Name System (DNS) Database", RFC 3403,
       October 2002.
 [4]   Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
       Four: The Uniform Resource Identifiers (URI) Resolution
       Application", RFC 3404, October 2002.
 [5]   Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
       Five: URI.ARPA Assignment Procedures", RFC 3405, October 2002.
 [6]   Moats, R., "URN Syntax", RFC 2141, November 1998.
 [7]   Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
       Resource Identifiers (URI): Generic Syntax", RFC 2396, August
       1998.
 [8]   Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet
       Mail Extensions (MIME) Part Four: Registration Procedures", BCP
       13, RFC 2048, November 1996.
 [9]   Faltstrom, P., Iannella, R., Daigle, L. and D. van Gulik, "URN
       Namespace Definition Mechanisms", BCP 33, RFC 2611, October
       1998.
 [10]  Petke, R. and I. King, "Registration Procedures for URL Scheme
       Names", BCP 35, RFC 2717, January 1999.

Mealling Best Current Practice [Page 8] RFC 3405 DDDS URI.ARPA Assignment Procedures October 2002

13. Author's Address

 Michael Mealling
 VeriSign
 21345 Ridgetop Circle
 Sterling, VA  20166
 US
 EMail: michael@neonym.net
 URI:  http://www.verisignlabs.com

Mealling Best Current Practice [Page 9] RFC 3405 DDDS URI.ARPA Assignment Procedures October 2002

14. Full Copyright Statement

 Copyright (C) The Internet Society (2002).  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.

Mealling Best Current Practice [Page 10]

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