Network Working Group F. Obser Internet-Draft RIPE NCC Intended status: Informational 24 June 2025 Expires: 26 December 2025 DNS Resolver Information Key for DELEG draft-fobser-resinfo-deleg-00 Abstract This document specifies a DNS Resolver Information Key to inform DNS clients of DELEG support. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 26 December 2025. Copyright Notice Copyright (c) 2025 IETF Trust and the persons identified as the document authors. All rights reserved. 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 of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 2 2. deleg Resolver Information Key . . . . . . . . . . . . . . . 2 3. Security Considerations . . . . . . . . . . . . . . . . . . . 2 Obser Expires 26 December 2025 [Page 1] Internet-Draft Resinfo DELEG June 2025 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. Normative References . . . . . . . . . . . . . . . . . . . . 3 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction The Extensible Delegation for DNS [I-D.draft-ietf-deleg] specifies the DELEG record type that is authoritative in the parent zone of a zone cut. To prevent downgrade attacks, [I-D.draft-ietf-deleg] introduces a new DNSKEY flag. A Validating Stub Resolver that is DELEG aware has to know if the Recursive Resolver it uses is DELEG aware. A DELEG aware Recursive Resolver using a Forwarder has to know if the Forwarder is DELEG aware. [RFC9606] specifies a DNS resource record (RR) type RESINFO to allow resolvers to publish information about their capabilities and policies. This can be used to inform DNS clients that DELEG is supported by the DNS resolver. 1.1. Requirements Notation 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. 2. deleg Resolver Information Key deleg: The presence of this key indicates that the DNS resolver supports DELEG. A resolver which supports [RFC9606] SHOULD add the deleg key if it supports [I-D.draft-ietf-deleg]. Note that, per the rules for the keys defined in Section 6.4 of [RFC6763], if there is no '=' in a key, then it is a boolean attribute, simply identified as being present, with no value. 3. Security Considerations The security considerations of [RFC9606] apply. Obser Expires 26 December 2025 [Page 2] Internet-Draft Resinfo DELEG June 2025 4. IANA Considerations The IANA is requested to add the key "deleg", with the description of "The presence of the key indicates that DELEG is supported.", and a reference to this document. +=======+===================================+===============+ | Name | Description | Reference | +=======+===================================+===============+ | deleg | The presence of the key indicates | RFC EDITOR: | | | that DELEG is supported. | THIS DOCUMENT | +-------+-----------------------------------+---------------+ Table 1 5. Normative References [I-D.draft-ietf-deleg] April, T., Špaček, P., Weber, R., and Lawrence, "Extensible Delegation for DNS", Work in Progress, Internet-Draft, draft-ietf-deleg-00, 6 May 2025, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC9606] Reddy.K, T. and M. Boucadair, "DNS Resolver Information", RFC 9606, DOI 10.17487/RFC9606, June 2024, . Author's Address Florian Obser RIPE NCC Email: florian+ietf@narrans.de Obser Expires 26 December 2025 [Page 3]