Moving DNSSEC Lookaside Validation (DLV) to Historic StatusISCNetherlandsmatthijs@isc.orgISCUSdmahoney@isc.org
Operations and Management
DNS OperationsDNSDNSSECDLVThis 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.
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(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
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Table of Contents
. Introduction
. Requirements Language
. Discussion
. Moving DLV to Historic Status
. Documents That Reference the DLV RFCs
. Documents That Reference RFC 4431
. Documents That Reference RFC 5074
. IANA Considerations
. Security Considerations
. Normative References
Acknowledgements
Authors' Addresses
IntroductionDNSSEC Lookaside Validation (DLV) was introduced to assist with the
adoption of DNSSEC 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.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
when, and only when, they appear in all capitals, as shown here.
DiscussionOne 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.Moving DLV to Historic StatusThere are two RFCs that specify DLV:
RFC 4431 specifies the
DLV resource record.
RFC 5074 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 and RFC 5074 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.Documents That Reference the DLV RFCsThe RFCs being moved to Historic status are referenced by a couple
of other RFCs.
The sections below describe the changes to those documents
due to the DLV RFCs being reclassified as Historic.
Documents That Reference RFC 4431One RFC makes reference to RFC 4431 .RFC 5074RFC 5074 ("DNSSEC Lookaside Validation (DLV)") describes the DLV mechanism itself. This
document moves RFC 5074
to Historic status as well.Documents That Reference RFC 5074Three RFCs make reference to RFC 5074 .RFC 6698RFC 6698 ("The DNS-Based Authentication of Named Entities (DANE)
Transport Layer Security (TLS) Protocol: TLSA") 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 to exclude the DLV resource record from
certificates.RFC 6840RFC 6840 ("Clarifications and Implementation Notes for DNS Security
(DNSSEC)") 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, this does not happen in validators
(both BIND 9 and Unbound have an option for a DLV trust anchor
that can be used solely as a fallback).This document updates RFC 6840 to exclude the DLV registries
from the trust anchor selection.RFC 8198RFC 8198 ("Aggressive Use of
DNSSEC-Validated Cache") only
references RFC 5074 because
aggressive negative caching was first proposed
there.IANA ConsiderationsIANA has updated the annotation of the DLV RR type (code 32769) to
"Obsolete" in the "Domain Name System (DNS) Parameters" registry.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.Normative ReferencesKey words for use in RFCs to Indicate Requirement LevelsIn many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.DNS Security Introduction and RequirementsThe Domain Name System Security Extensions (DNSSEC) add data origin authentication and data integrity to the Domain Name System. This document introduces these extensions and describes their capabilities and limitations. This document also discusses the services that the DNS security extensions do and do not provide. Last, this document describes the interrelationships between the documents that collectively describe DNSSEC. [STANDARDS-TRACK]Resource Records for the DNS Security ExtensionsThis document is part of a family of documents that describe the DNS Security Extensions (DNSSEC). The DNS Security Extensions are a collection of resource records and protocol modifications that provide source authentication for the DNS. This document defines the public key (DNSKEY), delegation signer (DS), resource record digital signature (RRSIG), and authenticated denial of existence (NSEC) resource records. The purpose and format of each resource record is described in detail, and an example of each resource record is given. This document obsoletes RFC 2535 and incorporates changes from all updates to RFC 2535. [STANDARDS-TRACK]Protocol Modifications for the DNS Security ExtensionsThis document is part of a family of documents that describe the DNS Security Extensions (DNSSEC). The DNS Security Extensions are a collection of new resource records and protocol modifications that add data origin authentication and data integrity to the DNS. This document describes the DNSSEC protocol modifications. This document defines the concept of a signed zone, along with the requirements for serving and resolving by using DNSSEC. These techniques allow a security-aware resolver to authenticate both DNS resource records and authoritative DNS error indications. This document obsoletes RFC 2535 and incorporates changes from all updates to RFC 2535. [STANDARDS-TRACK]The DNSSEC Lookaside Validation (DLV) DNS Resource RecordThis 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. This memo provides information for the Internet community.DNSSEC Lookaside Validation (DLV)DNSSEC Lookaside Validation (DLV) is a mechanism for publishing DNS Security (DNSSEC) trust anchors outside of the DNS delegation chain. It allows validating resolvers to validate DNSSEC-signed data from zones whose ancestors either aren't signed or don't publish Delegation Signer (DS) records for their children. This memo provides information for the Internet community.The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSAEncrypted communication on the Internet often uses Transport Layer Security (TLS), which depends on third parties to certify the keys used. This document improves on that situation by enabling the administrators of domain names to specify the keys used in that domain's TLS servers. This requires matching improvements in TLS client software, but no change in TLS server software. [STANDARDS-TRACK]Clarifications and Implementation Notes for DNS Security (DNSSEC)This document is a collection of technical clarifications to the DNS Security (DNSSEC) document set. It is meant to serve as a resource to implementors as well as a collection of DNSSEC errata that existed at the time of writing.This document updates the core DNSSEC documents (RFC 4033, RFC 4034, and RFC 4035) as well as the NSEC3 specification (RFC 5155). It also defines NSEC3 and SHA-2 (RFC 4509 and RFC 5702) as core parts of the DNSSEC specification.Ambiguity of Uppercase vs Lowercase in RFC 2119 Key WordsRFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.Aggressive Use of DNSSEC-Validated CacheThe DNS relies upon caching to scale; however, the cache lookup generally requires an exact match. This document specifies the use of NSEC/NSEC3 resource records to allow DNSSEC-validating resolvers to generate negative answers within a range and positive answers from wildcards. This increases performance, decreases latency, decreases resource utilization on both authoritative and recursive servers, and increases privacy. Also, it may help increase resilience to certain DoS attacks in some circumstances.This document updates RFC 4035 by allowing validating resolvers to generate negative answers based upon NSEC/NSEC3 records and positive answers in the presence of wildcards.AcknowledgementsThe authors thank for the initial review.Authors' AddressesISCNetherlandsmatthijs@isc.orgISCUSdmahoney@isc.org