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

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.¶

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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:¶

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:¶

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.¶

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 scenario actually occurs is very low, since no well-known DLV registry exists.¶

Acknowledgements

The authors thank Ondřej Surý for the initial review.¶

Authors' Addresses