Parental Reource Record Types in DNS

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Table of Contents

1. Introduction

The Delegation Signer (DS) Resource Record Type (RRtype) [RFC4034] has the unique property that the record is stored at the parental side of the delegation instead of at the child side. It is currently the only record with this property. As this property was a significant modification of the existing DNS protocol, it took many years for DNS software and DNS deployment to reliably serve and resolve this RRtype. Since then, a number of proposals have surfaces that wanted to create similarly behaving RRtypes. This document updates [DNS RFCs] to generalize this property of resolving at the parental side of a delegation for future RRtypes that fall within a predefined RRtype range.¶

This document modifies the DNS Parameters' Resource Record (RR) TYPEs registry to reserve 256 RRtypes that have this property. The goal is that a number of years from now, new RRtypes that want to be resolved at the parental side of a delegation can be specified without incurring another time penality for waiting on DNS implementations and deployment updates of DNS authoritative servers and DNS resolver implementations. This uses the same deployment strategy as the Unknown Resource Records [RFC3597].¶

2. Parental RRtype

A new property "Parental RRtype" is defined to mean that this RRtype MUST only be resolved at the parental side of a zone delegation. This flag is only set for the existing DS RRtype and a new range of RRtypes specified by this document below.¶

3. Operational Considerations

For Top Level Domains (TLDs), which generally use a Registry, Registrar, Registrant model, it is RECOMMENDED that new Parental RRtypes support a DNS mechanism that allows the introduction, update and deletion of these RRtypes by the DNS Hoster of the child zone. Failing such a mechanism, deployments will still see considerable (seveal years or more) delays in universal deployment of their Parental RRtype. Even though the DNS protool will resolve these records without issue, updates will be required to the EPP protocol [RFC5730] (and its reseller subsystems), Registrar software and deployment and Registrant (enduser) capability of entering such new (possibly complicated) RRtype data into a Registrar website.¶

4. Security Considerations

New Parental RRtypes related to security or privacy SHOULD require DNSSEC [RFC9364], especially if no other trust path (eg WebPKI) is available within the RRdata of the new Parental RRtype.¶

In general, RRtypes that wish to store data at the parent side of a delegation contains information that is preferably conveyed to the DNS resolver before connecting to the child zone's name servers specified in the NS RRtype of the zone and generally are assumed to increase security and reliability of the DNS.¶

Any future Parental RRtype defined MUST contemplate the security implications of their RRtype getting resolved at the wrong (child) location by old DNS software.¶

If a new Parental RRtype contains security context that the child zone owner would like to confirm it supports (or not), this could be signed by using a new DNSKEY flag, see RFCxxxxx Section yyy.¶

DNS resolvers, especially actively maintained public facing large DNS resolvers, MAY disable those Parental RRtypes values that have not yet been allocated to prevent abuse, with the expectation that once a Parentl RRtype is allocated, that support for these is then promptly enabled.¶

what else ?¶

5. IANA considerations

This document updates the Record Resource (RR) TYPEs IANA Registry listed under the DNS Parameters IANA Registry as follows:¶

This document is added to the Reference section.¶

6. Yang Model Update

update RFC 9108 for yang. TODO¶

Appendix A. Acknowledgments

The idea of having more than just the DS record resolve at the parent has been suggested a number of times by people in the past. The idea of confirming a zone property to the parent via DNSKEY flag was first proposed by the DELEGATION_ONLY draft. Both were made popular by the DELEG RRtype initiative.¶

This was written before I realised there was a very short scaffolding draft on the same topic: draft-peetterr-dnsop-parent-side-auth-types¶

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