5Internet Engineering Task Force (IETF) W. Mekking
6Request for Comments: 8749 D. Mahoney
8Category: Standards Track March 2020
12 Moving DNSSEC Lookaside Validation (DLV) to Historic Status
16 This document retires DNSSEC Lookaside Validation (DLV) and
17 reclassifies RFCs 4431 and 5074 as Historic. Furthermore, this
18 document updates RFC 6698 by excluding the DLV resource record from
19 certificates and updates RFC 6840 by excluding the DLV registries
20 from the trust anchor selection.
24 This is an Internet Standards Track document.
26 This document is a product of the Internet Engineering Task Force
27 (IETF). It represents the consensus of the IETF community. It has
28 received public review and has been approved for publication by the
29 Internet Engineering Steering Group (IESG). Further information on
30 Internet Standards is available in Section 2 of RFC 7841.
32 Information about the current status of this document, any errata,
33 and how to provide feedback on it may be obtained at
34 https://www.rfc-editor.org/info/rfc8749.
38 Copyright (c) 2020 IETF Trust and the persons identified as the
39 document authors. All rights reserved.
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49 described in the Simplified BSD License.
54 2. Requirements Language
56 4. Moving DLV to Historic Status
57 4.1. Documents That Reference the DLV RFCs
58 4.1.1. Documents That Reference RFC 4431
59 4.1.2. Documents That Reference RFC 5074
60 5. IANA Considerations
61 6. Security Considerations
62 7. Normative References
68 DNSSEC Lookaside Validation (DLV) was introduced to assist with the
69 adoption of DNSSEC [RFC4033] [RFC4034] [RFC4035] in a time when the
70 root zone and many top-level domains (TLDs) were unsigned. DLV
71 allowed entities with signed zones under an unsigned parent zone or
72 entities with registrars that did not accept DS records to publish
73 trust anchors outside of the normal DNS delegation chain. The root
74 zone was signed in July 2010, and as of May 2019, 1389 out of 1531
75 TLDs have a secure delegation from the root; thus, DLV has served its
76 purpose and can now retire.
782. Requirements Language
80 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
81 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
82 "OPTIONAL" in this document are to be interpreted as described in
83 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
84 capitals, as shown here.
88 One could argue that DLV is still useful because there are still some
89 unsigned TLDs and entities under those zones that will not benefit
90 from signing their zone. However, keeping the DLV mechanism also has
93 * It reduces the pressure to get the parent zone signed.
95 * It reduces the pressure on registrars to accept DS records.
97 * It complicates validation code.
99 In addition, not every validator actually implemented DLV (only BIND
100 9 and Unbound), so even if an entity can use DLV to set up an
101 alternate path to its trust anchor, its effect is limited.
102 Furthermore, there was one well-known DLV registry (dlv.isc.org),
103 which was deprecated (replaced with a signed empty zone) on September
104 30, 2017. With the absence of a well-known DLV registry service, it
105 is unlikely that there is a real benefit for the protocol on the
108 One other possible reason to keep DLV is to distribute trust anchors
109 for private enterprises. There are no known uses of DLV for this.
111 All things considered, it is probably not worth the effort of
112 maintaining the DLV mechanism.
1144. Moving DLV to Historic Status
116 There are two RFCs that specify DLV:
118 1. RFC 4431 [RFC4431] specifies the DLV resource record.
120 2. RFC 5074 [RFC5074] specifies the DLV mechanism for publishing
121 trust anchors outside the DNS delegation chain and how validators
122 can use them to validate DNSSEC-signed data.
124 This document moves both RFC 4431 [RFC4431] and RFC 5074 [RFC5074] to
125 Historic status. This is a clear signal to implementers that the DLV
126 resource record and the DLV mechanism SHOULD NOT be implemented or
1294.1. Documents That Reference the DLV RFCs
131 The RFCs being moved to Historic status are referenced by a couple of
132 other RFCs. The sections below describe the changes to those
133 documents due to the DLV RFCs being reclassified as Historic.
1354.1.1. Documents That Reference RFC 4431
137 One RFC makes reference to RFC 4431 [RFC4431].
141 RFC 5074 ("DNSSEC Lookaside Validation (DLV)") [RFC5074] describes
142 the DLV mechanism itself. This document moves RFC 5074 [RFC5074] to
143 Historic status as well.
1454.1.2. Documents That Reference RFC 5074
147 Three RFCs make reference to RFC 5074 [RFC5074].
151 RFC 6698 ("The DNS-Based Authentication of Named Entities (DANE)
152 Transport Layer Security (TLS) Protocol: TLSA") [RFC6698] specifies:
154 | DNSSEC forms certificates (the binding of an identity to a key) by
155 | combining a DNSKEY, DS, or DLV resource record with an associated
156 | RRSIG record. These records then form a signing chain extending
157 | from the client's trust anchors to the RR of interest.
159 This document updates RFC 6698 [RFC6698] to exclude the DLV resource
160 record from certificates.
164 RFC 6840 ("Clarifications and Implementation Notes for DNS Security
165 (DNSSEC)") [RFC6840] states that when trust anchors come from
166 different sources, a validator may choose between them based on the
167 perceived reliability of those sources. But in reality, this does
168 not happen in validators (both BIND 9 and Unbound have an option for
169 a DLV trust anchor that can be used solely as a fallback).
171 This document updates RFC 6840 [RFC6840] to exclude the DLV
172 registries from the trust anchor selection.
176 RFC 8198 ("Aggressive Use of DNSSEC-Validated Cache") [RFC8198] only
177 references RFC 5074 [RFC5074] because aggressive negative caching was
178 first proposed there.
1805. IANA Considerations
182 IANA has updated the annotation of the DLV RR type (code 32769) to
183 "Obsolete" in the "Domain Name System (DNS) Parameters" registry.
1856. Security Considerations
187 Once the DLV mechanism is retired, zones that rely on DLV for their
188 validation will be treated as insecure. The chance that this
189 scenario actually occurs is very low, since no well-known DLV
1927. Normative References
194 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
195 Requirement Levels", BCP 14, RFC 2119,
196 DOI 10.17487/RFC2119, March 1997,
197 <https://www.rfc-editor.org/info/rfc2119>.
199 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
200 Rose, "DNS Security Introduction and Requirements",
201 RFC 4033, DOI 10.17487/RFC4033, March 2005,
202 <https://www.rfc-editor.org/info/rfc4033>.
204 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
205 Rose, "Resource Records for the DNS Security Extensions",
206 RFC 4034, DOI 10.17487/RFC4034, March 2005,
207 <https://www.rfc-editor.org/info/rfc4034>.
209 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
210 Rose, "Protocol Modifications for the DNS Security
211 Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
212 <https://www.rfc-editor.org/info/rfc4035>.
214 [RFC4431] Andrews, M. and S. Weiler, "The DNSSEC Lookaside
215 Validation (DLV) DNS Resource Record", RFC 4431,
216 DOI 10.17487/RFC4431, February 2006,
217 <https://www.rfc-editor.org/info/rfc4431>.
219 [RFC5074] Weiler, S., "DNSSEC Lookaside Validation (DLV)", RFC 5074,
220 DOI 10.17487/RFC5074, November 2007,
221 <https://www.rfc-editor.org/info/rfc5074>.
223 [RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
224 of Named Entities (DANE) Transport Layer Security (TLS)
225 Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
226 2012, <https://www.rfc-editor.org/info/rfc6698>.
228 [RFC6840] Weiler, S., Ed. and D. Blacka, Ed., "Clarifications and
229 Implementation Notes for DNS Security (DNSSEC)", RFC 6840,
230 DOI 10.17487/RFC6840, February 2013,
231 <https://www.rfc-editor.org/info/rfc6840>.
233 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
234 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
235 May 2017, <https://www.rfc-editor.org/info/rfc8174>.
237 [RFC8198] Fujiwara, K., Kato, A., and W. Kumari, "Aggressive Use of
238 DNSSEC-Validated Cache", RFC 8198, DOI 10.17487/RFC8198,
239 July 2017, <https://www.rfc-editor.org/info/rfc8198>.
243 The authors thank Ondřej Surý for the initial review.
247 W. (Matthijs) Mekking
251 Email: matthijs@isc.org
256 United States of America
258 Email: dmahoney@isc.org