Network Working Group                                         M. Andrews
Request for Comments: 4431                   Internet Systems Consortium
Category: Informational                                        S. Weiler
                                                           SPARTA, Inc.
                                                          February 2006


      The DNSSEC Lookaside Validation (DLV) DNS Resource Record

Status of This Memo

  This memo provides information for the Internet community.  It does
  not specify an Internet standard of any kind.  Distribution of this
  memo is unlimited.

Copyright Notice

  Copyright (C) The Internet Society (2006).

Abstract

  This document defines a new DNS resource record, called the DNSSEC
  Lookaside Validation (DLV) RR, for publishing DNSSEC trust anchors
  outside of the DNS delegation chain.

1.  Introduction

  DNSSEC [1] [2] [3] authenticates DNS data by building public-key
  signature chains along the DNS delegation chain from a trust anchor,
  ideally a trust anchor for the DNS root.

  This document defines a new resource record for publishing such trust
  anchors outside of the DNS's normal delegation chain.  Use of these
  records by DNSSEC validators is outside the scope of this document,
  but it is expected that these records will help resolvers validate
  DNSSEC-signed data from zones whose ancestors either aren't signed or
  refuse to publish delegation signer (DS) records for their children.

2.  DLV Resource Record

  The DLV resource record has exactly the same wire and presentation
  formats as the DS resource record, defined in RFC 4034, Section 5.
  It uses the same IANA-assigned values in the algorithm and digest
  type fields as the DS record.  (Those IANA registries are known as
  the "DNS Security Algorithm Numbers" and "DS RR Type Algorithm
  Numbers" registries.)





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  The DLV record is a normal DNS record type without any special
  processing requirements.  In particular, the DLV record does not
  inherit any of the special processing or handling requirements of the
  DS record type (described in Section 3.1.4.1 of RFC 4035).  Unlike
  the DS record, the DLV record may not appear on the parent's side of
  a zone cut.  A DLV record may, however, appear at the apex of a zone.

3.  Security Considerations

  For authoritative servers and resolvers that do not attempt to use
  DLV RRs as part of DNSSEC validation, there are no particular
  security concerns -- DLV RRs are just like any other DNS data.

  Software using DLV RRs as part of DNSSEC validation will almost
  certainly want to impose constraints on their use, but those
  constraints are best left to be described by the documents that more
  fully describe the particulars of how the records are used.  At a
  minimum, it would be unwise to use the records without some sort of
  cryptographic authentication.  More likely than not, DNSSEC itself
  will be used to authenticate the DLV RRs.  Depending on how a DLV RR
  is used, failure to properly authenticate it could lead to
  significant additional security problems including failure to detect
  spoofed DNS data.

  RFC 4034, Section 8, describes security considerations specific to
  the DS RR.  Those considerations are equally applicable to DLV RRs.
  Of particular note, the key tag field is used to help select DNSKEY
  RRs efficiently, but it does not uniquely identify a single DNSKEY
  RR.  It is possible for two distinct DNSKEY RRs to have the same
  owner name, the same algorithm type, and the same key tag.  An
  implementation that uses only the key tag to select a DNSKEY RR might
  select the wrong public key in some circumstances.

  For further discussion of the security implications of DNSSEC, see
  RFC 4033, RFC 4034, and RFC 4035.

4.  IANA Considerations

  IANA has assigned DNS type code 32769 to the DLV resource record from
  the Specification Required portion of the DNS Resource Record Type
  registry, as defined in [4].

  The DLV resource record reuses the same algorithm and digest type
  registries already used for the DS resource record, currently known
  as the "DNS Security Algorithm Numbers" and "DS RR Type Algorithm
  Numbers" registries.





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5.  Normative References

  [1]  Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
       "DNS Security Introduction and Requirements", RFC 4033,
       March 2005.

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

  [3]  Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
       "Protocol Modifications for the DNS Security Extensions",
       RFC 4035, March 2005.

  [4]  Eastlake, D., Brunner-Williams, E., and B. Manning, "Domain Name
       System (DNS) IANA Considerations", BCP 42, RFC 2929,
       September 2000.

Authors' Addresses

  Mark Andrews
  Internet Systems Consortium
  950 Charter St.
  Redwood City, CA  94063
  US

  EMail: [email protected]


  Samuel Weiler
  SPARTA, Inc.
  7075 Samuel Morse Drive
  Columbia, Maryland  21046
  US

  EMail: [email protected]















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Full Copyright Statement

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Acknowledgement

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  Administrative Support Activity (IASA).







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