Moving DNSSEC Lookaside Validation (DLV) to Historic Status
RFC 8749

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Internet Engineering Task Force (IETF)                        W. Mekking
Request for Comments: 8749                                    D. Mahoney
Updates: 6698, 6840                                                  ISC
Category: Standards Track                                     March 2020
ISSN: 2070-1721

      Moving DNSSEC Lookaside Validation (DLV) to Historic Status

Abstract

   This document retires DNSSEC Lookaside Validation (DLV) and
   reclassifies RFCs 4431 and 5074 as Historic.  Furthermore, this
   document updates RFC 6698 by excluding the DLV resource record from
   certificates and updates RFC 6840 by excluding the DLV registries
   from the trust anchor selection.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8749.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction
   2.  Requirements Language
   3.  Discussion
   4.  Moving DLV to Historic Status
     4.1.  Documents That Reference the DLV RFCs
       4.1.1.  Documents That Reference RFC 4431
       4.1.2.  Documents That Reference RFC 5074
   5.  IANA Considerations
   6.  Security Considerations
   7.  Normative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   DNSSEC Lookaside Validation (DLV) was introduced to assist with the
   adoption of DNSSEC [RFC4033] [RFC4034] [RFC4035] in a time when the
   root zone and many top-level domains (TLDs) were unsigned.  DLV
   allowed entities with signed zones under an unsigned parent zone or
   entities with registrars that did not accept DS records to publish
   trust anchors outside of the normal DNS delegation chain.  The root
   zone was signed in July 2010, and as of May 2019, 1389 out of 1531
   TLDs have a secure delegation from the root; thus, DLV has served its
   purpose and can now retire.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Discussion

   One could argue that DLV is still useful because there are still some
   unsigned TLDs and entities under those zones that will not benefit
   from signing their zone.  However, keeping the DLV mechanism also has
   disadvantages:

   *  It reduces the pressure to get the parent zone signed.

   *  It reduces the pressure on registrars to accept DS records.

   *  It complicates validation code.

   In addition, not every validator actually implemented DLV (only BIND
   9 and Unbound), so even if an entity can use DLV to set up an
   alternate path to its trust anchor, its effect is limited.
   Furthermore, there was one well-known DLV registry (dlv.isc.org),
   which was deprecated (replaced with a signed empty zone) on September
   30, 2017.  With the absence of a well-known DLV registry service, it
   is unlikely that there is a real benefit for the protocol on the
   Internet nowadays.

   One other possible reason to keep DLV is to distribute trust anchors
   for private enterprises.  There are no known uses of DLV for this.

   All things considered, it is probably not worth the effort of
   maintaining the DLV mechanism.

4.  Moving DLV to Historic Status

   There are two RFCs that specify DLV:

   1.  RFC 4431 [RFC4431] specifies the DLV resource record.

   2.  RFC 5074 [RFC5074] specifies the DLV mechanism for publishing
       trust anchors outside the DNS delegation chain and how validators
       can use them to validate DNSSEC-signed data.

   This document moves both RFC 4431 [RFC4431] and RFC 5074 [RFC5074] to
   Historic status.  This is a clear signal to implementers that the DLV
   resource record and the DLV mechanism SHOULD NOT be implemented or