RFC 8749

Moving DNSSEC Lookaside Validation (DLV) to Historic Status

📅 published March 2020, from ietf

Moving DNSSEC Lookaside Validation (DLV) to Historic Status ✨

Okay bestie, this one is a tea spill about a protocol that's finally retiring 🫖💅 Let's get into it.

Internet Engineering Task Force (IETF) 🎀 Authors: W. Mekking and D. Mahoney (both from ISC) 🦋 Category: Standards Track 💜 Date: March 2020 🌸 Updates: 6698, 6840 ⭐ Obsoletes: nothing (it doesn't replace anything, it just retires DLV) 🙈 ISSN: 2070-1721 ✨

Abstract

Okay so the TL;DR is: this doc retires DNSSEC Lookaside Validation (DLV) 🔥 and reclassifies RFCs 4431 and 5074 as Historic 💀. It also 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 💅. Iconic retirement arc, honestly.

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, received public review, and got approved for publication by the Internet Engineering Steering Group (IESG) 👑. More info on Internet Standards is in Section 2 of RFC 7841 💜.

Info about the current status of this document, any errata, and how to send feedback lives at https://www.rfc-editor.org/info/rfc8749 🌸.

Copyright Notice 💖

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication 📜. Please review these carefully, because they describe your rights and restrictions. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions, and they're provided without warranty as described in the Simplified BSD License 💜.

Table of Contents 🧚

Introduction
Requirements Language
Discussion
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
IANA Considerations
Security Considerations
Normative References Acknowledgements Authors' Addresses

1. Introduction 🌸

Okay, so DLV was introduced to help DNSSEC [RFC4033] [RFC4034] [RFC4035] get adopted back when the root zone and lots of top-level domains (TLDs) were still unsigned 🙈. It let entities with signed zones under an unsigned parent, or entities whose registrars wouldn't accept DS records, publish trust anchors outside the normal DNS delegation chain 🧚.

The root zone got signed in July 2010, and as of May 2019, 1389 out of 1531 TLDs had a secure delegation from the root. So DLV has served its purpose and can finally 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 🦋

Someone could argue DLV is still useful, because some TLDs are still unsigned and entities under them won't benefit from signing their zone 🤔. But keeping the DLV mechanism has downsides too:

It reduces the pressure to get the parent zone signed.
It reduces the pressure on registrars to accept DS records.
It complicates validation code.

Also, not every validator actually implemented DLV (only BIND 9 and Unbound did) 💀, so even if an entity uses DLV to set up an alternate path to its trust anchor, the effect is limited. Plus, there was one well-known DLV registry (dlv.isc.org), which got deprecated (replaced with a signed empty zone) on September 30, 2017 😭. With no well-known DLV registry service around, it's unlikely there's a real benefit for the protocol on the Internet nowadays 🥀.

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

All things considered, it's probably not worth the effort of maintaining the DLV mechanism 💅👑.

4. Moving DLV to Historic Status 🧚‍♀️

There are two RFCs that specify DLV:

RFC 4431 [RFC4431] specifies the DLV resource record.
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 deployed 🚫💖.

4.1. Documents That Reference the DLV RFCs 💜

The RFCs being moved to Historic status are referenced by a couple of other RFCs 🦋. The sections below describe the changes to those documents because the DLV RFCs are being reclassified as Historic ✨.

4.1.1. Documents That Reference RFC 4431 🌸

One RFC references RFC 4431 [RFC4431] 🎀.

4.1.1.1. RFC 5074 🫶

RFC 5074 ("DNSSEC Lookaside Validation (DLV)") [RFC5074] describes the DLV mechanism itself. This document moves RFC 5074 [RFC5074] to Historic status as well 💅.

4.1.2. Documents That Reference RFC 5074 🧚

Three RFCs reference RFC 5074 [RFC5074] 👑.

4.1.2.1. RFC 6698 ⭐

RFC 6698 ("The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSA") [RFC6698] specifies:

DNSSEC forms certificates (the binding of an identity to a key) by combining a DNSKEY, DS, or DLV resource record with an associated RRSIG record. These records then form a signing chain extending from the client's trust anchors to the RR of interest.

This document updates RFC 6698 [RFC6698] to exclude the DLV resource record from certificates 🔥.

4.1.2.2. RFC 6840 🌈

RFC 6840 ("Clarifications and Implementation Notes for DNS Security (DNSSEC)") [RFC6840] states that when trust anchors come from different sources, a validator may choose between them based on the perceived reliability of those sources. But in reality, that doesn't happen in validators: both BIND 9 and Unbound have an option for a DLV trust anchor that can only be used as a fallback 🙃.

This document updates RFC 6840 [RFC6840] to exclude the DLV registries from the trust anchor selection 💖.

4.1.2.3. RFC 8198 💜

RFC 8198 ("Aggressive Use of DNSSEC-Validated Cache") [RFC8198] only references RFC 5074 [RFC5074] because aggressive negative caching was first proposed there 🦋.

5. IANA Considerations 🎀

IANA has updated the annotation of the DLV RR type (code 32769) to Obsolete in the "Domain Name System (DNS) Parameters" registry 📋✨.

6. Security Considerations 💀

Once the DLV mechanism is retired, zones that rely on DLV for their validation will be treated as insecure 😱. The chance that this actually happens is very low, since no well-known DLV registry exists 🫣🫶.

7. Normative References 📚

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119,
           DOI 10.17487/RFC2119, March 1997,
           <https://www.rfc-editor.org/info/rfc2119>.

[RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
           Rose, "DNS Security Introduction and Requirements",
           RFC 4033, DOI 10.17487/RFC4033, March 2005,
           <https://www.rfc-editor.org/info/rfc4033>.

[RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
           Rose, "Resource Records for the DNS Security Extensions",
           RFC 4034, DOI 10.17487/RFC4034, March 2005,
           <https://www.rfc-editor.org/info/rfc4034>.

[RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
           Rose, "Protocol Modifications for the DNS Security
           Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
           <https://www.rfc-editor.org/info/rfc4035>.

[RFC4431]  Andrews, M. and S. Weiler, "The DNSSEC Lookaside
           Validation (DLV) DNS Resource Record", RFC 4431,
           DOI 10.17487/RFC4431, February 2006,
           <https://www.rfc-editor.org/info/rfc4431>.

[RFC5074]  Weiler, S., "DNSSEC Lookaside Validation (DLV)", RFC 5074,
           DOI 10.17487/RFC5074, November 2007,
           <https://www.rfc-editor.org/info/rfc5074>.

[RFC6698]  Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
           of Named Entities (DANE) Transport Layer Security (TLS)
           Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
           2012, <https://www.rfc-editor.org/info/rfc6698>.

[RFC6840]  Weiler, S., Ed. and D. Blacka, Ed., "Clarifications and
           Implementation Notes for DNS Security (DNSSEC)", RFC 6840,
           DOI 10.17487/RFC6840, February 2013,
           <https://www.rfc-editor.org/info/rfc6840>.

[RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
           2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
           May 2017, <https://www.rfc-editor.org/info/rfc8174>.

[RFC8198]  Fujiwara, K., Kato, A., and W. Kumari, "Aggressive Use of
           DNSSEC-Validated Cache", RFC 8198, DOI 10.17487/RFC8198,
           July 2017, <https://www.rfc-editor.org/info/rfc8198>.

Acknowledgements 🫶

The authors thank Ondřej Surý for the initial review 💖🌸.

Authors' Addresses 🦋

W. (Matthijs) Mekking
ISC
Netherlands

Email: matthijs@isc.org


Dan Mahoney
ISC
United States of America

Email: dmahoney@isc.org

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