RFC 9975 · PROPOSED STANDARD · 2026

Clarifications on CDS/CDNSKEY and CSYNC Consistency

Overview

RFC 9975, “Clarifications on CDS/CDNSKEY and CSYNC Consistency”, is a Proposed Standard document published in May 2026 by P. Thomassen. It updates RFC 7344, RFC 7477. The canonical text is published by the RFC Editor.

Abstract

Maintenance of DNS delegations requires occasional changes of the DS and NS record sets on the parent side of the delegation. For the case of DS records, "Automating DNSSEC Delegation Trust Maintenance" (RFC 7344) provides automation by allowing the child to publish CDS and/or CDNSKEY records holding the prospective DS parameters that the parent can ingest. Similarly, "Child-to-Parent Synchronization in DNS" (RFC 7477) specifies CSYNC records to indicate a desired update of the delegation's NS (and glue) records. Parent-side entities (e.g., Registries and Registrars) can query these records from the child and, after validation, use them to update the parent-side Resource Record Sets (RRsets) of the delegation.

This document specifies under which conditions the target states expressed via CDS/CDNSKEY and CSYNC records are considered "consistent". Parent-side entities accepting such records from the child have to ensure that update requests retrieved from different authoritative nameservers satisfy these consistency requirements before taking any action based on them.

This document updates RFCs 7344 and 7477.

Abstract as published in the RFC, via rfc-editor.org.

What “Proposed Standard” means

An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.

Read this RFC

The canonical text of RFC 9975 is hosted at rfc-editor.org. Available in HTML,TXT,PDF,XML.

Relationships to other RFCs
This RFC updates
RFC 7344 RFC 7477
Other RFCs from 2026

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