RFC 4431

RFC 4431 🎀 The DNSSEC Lookaside Validation (DLV) DNS Resource Record

Title block, the tea ☕

• Network Working Group 🌸
• Request for Comments: 4431
• Category: Informational. It's for the Internet community, not an official standard. 🧚
• Date: February 2006
• Authors: Mark Andrews (Internet Systems Consortium) and Samuel Weiler (SPARTA, Inc.) 💜
• Obsoletes / Updates: the header doesn't list any RFCs it obsoletes or updates. 🦋

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Status of This Memo 📜

okay bestie, this memo gives information to the Internet community. It is NOT a spec for an Internet standard of any kind 🙈 Distribution of this memo is unlimited, so share it with everyone 💖

Copyright Notice ©️

Copyright (C) The Internet Society (2006). ✨

Abstract 🦋

so this doc defines a brand new DNS resource record called the DNSSEC Lookaside Validation (DLV) RR. Its whole job is publishing DNSSEC trust anchors outside of the DNS delegation chain 🔥

1. Introduction ✨

okay, quick refresher. DNSSEC [1] [2] [3] authenticates DNS data by building public-key signature chains along the DNS delegation chain, starting from a trust anchor. Ideally that trust anchor is for the DNS root 👑

this doc defines a new resource record for publishing those trust anchors outside the DNS's normal delegation chain. How DNSSEC validators actually use these records is outside this document's scope, so that's a later chapter 📖 The expectation is that these records will help resolvers validate DNSSEC-signed data from zones whose ancestors either aren't signed, or refuse to publish delegation signer (DS) records for their children. Lowkey the whole point, honestly 🫶

2. DLV Resource Record 💅

the DLV resource record has exactly the same wire and presentation formats as the DS resource record, defined in RFC 4034, Section 5. Same vibe, same format 🎀 It also uses the same IANA-assigned values in the algorithm and digest type fields as the DS record. (Those IANA registries are known as the "DNS Security Algorithm Numbers" and "DS RR Type Algorithm Numbers" registries. 📚)

The DLV record is a normal DNS record type with no special processing requirements. ✨ It does NOT inherit any of the special processing or handling requirements of the DS record type, which are described in Section 3.1.4.1 of RFC 4035. Unlike the DS record, the DLV record may not appear on the parent's side of a zone cut. 🙅‍♀️ It can, however, appear at the apex of a zone. 👑

3. Security Considerations 🔐

⚠️ Serious bestie moment. Read this part carefully. ⚠️

For authoritative servers and resolvers that do NOT attempt to use DLV RRs as part of DNSSEC validation, there are no particular security concerns. DLV RRs are just like any other DNS data 🌸

Software that DOES use DLV RRs as part of DNSSEC validation will almost certainly want to impose constraints on their use. Those constraints are best left to documents that more fully describe the particulars of how the records get used 📖 At a minimum, it would be unwise to use the records without some sort of cryptographic authentication. 💀 More likely than not, DNSSEC itself will be used to authenticate the DLV RRs. Depending on how a DLV RR is used, failing to properly authenticate it could lead to significant additional security problems, including failure to detect spoofed DNS data. 😭

RFC 4034, Section 8, describes security considerations specific to the DS RR. Those considerations are equally applicable to DLV RRs 🫶 Of particular note: the key tag field is used to help select DNSKEY RRs efficiently, but it does NOT uniquely identify a single DNSKEY RR. It is possible for two distinct DNSKEY RRs to have the same owner name, the same algorithm type, and the same key tag. An implementation that uses only the key tag to select a DNSKEY RR might select the wrong public key in some circumstances. 🙈

For further discussion of the security implications of DNSSEC, see RFC 4033, RFC 4034, and RFC 4035 🧚

4. IANA Considerations 🌈

IANA has assigned DNS type code 32769 to the DLV resource record from the Specification Required portion of the DNS Resource Record Type registry, as defined in [4] 💜

The DLV resource record reuses the same algorithm and digest type registries already used for the DS resource record. Those are currently known as the "DNS Security Algorithm Numbers" and "DS RR Type Algorithm Numbers" registries. 🍓

5. Normative References 📚

• [1] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, March 2005. ✨
• [2] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Resource Records for the DNS Security Extensions", RFC 4034, March 2005. 🎀
• [3] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Protocol Modifications for the DNS Security Extensions", RFC 4035, March 2005. 💅
• [4] Eastlake, D., Brunner-Williams, E., and B. Manning, "Domain Name System (DNS) IANA Considerations", BCP 42, RFC 2929, September 2000. 🦋

Authors' Addresses 📮

• Mark Andrews Internet Systems Consortium 950 Charter St. Redwood City, CA 94063 US EMail: Mark_Andrews@isc.org 💖
• Samuel Weiler SPARTA, Inc. 7075 Samuel Morse Drive Columbia, Maryland 21046 US EMail: weiler@tislabs.com 🫶

Full Copyright Statement ©️

Copyright (C) The Internet Society (2006). ✨

This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 👑

This document and the information contained herein are provided on an "AS IS" basis, and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 😭

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Acknowledgement 🌈

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