DNS Backend Serial Zone Version Option

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Table of Contents

1. Discussion Venues

This note is to be removed before publishing as an RFC.¶

Source for this draft and an issue tracker can be found at https://github.com/SIDN/ietf-zoneversion-extended.git .¶

2. Introduction

The DNS Backend Serial Zone Version Option is a way to get information about the version of a DNS zone in the backend. For example when a DNSSEC signer for a zone generates a new SOA serial, because it has created new RRSIG records, the original data has not changed, but this is not visible to anyone looking at the zone. This document makes it possible to retreive the backend version that is the source of data in the DNS response.¶

3. Terminology and Definitions

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.¶

4. Relation to the ZONEVERSION option

This document extends the original DNS Zone version Option [!@RFC9660] to include an extra ZONEVERSION type.¶

5. The backend serial in the zone

To make the backend serial available in the ZONEVERSION, it must be available in the zone itself. Because creating an out of bound solution would be to much work. This document defines a label where the backend serial will be available to be used in the ZONEVERSION.¶

The backend serial will be published in a _backend-version label under the zone apex.¶

For example:¶

_backend-version.example.nl IN TXT "2025101099"

The setting of the value of the _backend-version label is out of scope for this document. The RDATA is not limited to a 32-bit number, like the SOA-SERIAL. It can be any string.¶

There MUST only be one _backend-version label.¶

6. The backend serial ZONEVERSION type

This document defines a new ZONEVERSION option TYPE, which can be constructed from RDATA in the zone.¶

The mnemonic for this type is "BACKEND-SERIAL".¶

The VERSION value for the BACKEND-SERIAL type MUST come from the RDATA of the _backend-version label in the zone. Unless the software already knows the backend serial, then it SHOULD use that. If there are multiple _backend-version labels at the zone apex, these MUST all be ignored.¶

7. Security Considerations

When using the backend serial zoneversion option it will reveal a small bit of information of your backend to the world. This should be a consius decission.¶

8. IANA Considerations

9. Acknowledgements

Many thanks to original authors of [RFC9660]. And the following reviewers: Peter van Dijk.¶

Appendix A. Change History (to be removed before publication)

• draft-ubbink-dnsop-backend-serial-zoneversion-00¶

Use a better name for the draft. Use a different label for the backend version. Add security considerations¶

• draft-ubbink-zoneversion...¶

Initial publication¶

Author's Address