NSEC(3) TTLs and NSEC Aggressive Use
draft-ietf-dnsop-nsec-ttl-00
dnsop P. van Dijk
Internet-Draft PowerDNS
Updates: 4034, 4035, 5155 (if approved) 13 January 2021
Intended status: Standards Track
Expires: 17 July 2021
NSEC(3) TTLs and NSEC Aggressive Use
draft-ietf-dnsop-nsec-ttl-00
Abstract
Due to a combination of unfortunate wording in earlier documents,
aggressive use of NSEC(3) records may deny names far beyond the
intended lifetime of a denial. This document changes the definition
of the NSEC(3) TTL to correct that situation. This document updates
RFC 4034, RFC 4035, and RFC 5155.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 17 July 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4
3. NSEC(3) TTL changes . . . . . . . . . . . . . . . . . . . . . 4
3.1. Updates to RFC4034 . . . . . . . . . . . . . . . . . . . 4
3.2. Updates to RFC4035 . . . . . . . . . . . . . . . . . . . 4
3.3. Updates to RFC5155 . . . . . . . . . . . . . . . . . . . 4
3.4. No updates to RFC8198 . . . . . . . . . . . . . . . . . . 5
4. Zone Operator Considerations . . . . . . . . . . . . . . . . 5
4.1. A Note On Wildcards . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 6
8. Informative References . . . . . . . . . . . . . . . . . . . 6
Appendix A. Implementation Status . . . . . . . . . . . . . . . 6
Appendix B. Document history . . . . . . . . . . . . . . . . . . 7
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[RFC editor: please remove this block before publication.
Earlier notes on this:
* https://indico.dns-oarc.net/event/29/sessions/98/#20181013
(https://indico.dns-oarc.net/event/29/sessions/98/#20181013)
* https://lists.dns-oarc.net/pipermail/dns-operations/2018-April/
thread.html#17420 (https://lists.dns-oarc.net/pipermail/dns-
operations/2018-April/thread.html#17420)
* https://lists.dns-oarc.net/pipermail/dns-
operations/2018-March/017416.html (https://lists.dns-
oarc.net/pipermail/dns-operations/2018-March/017416.html)
This document lives on GitHub (https://github.com/PowerDNS/draft-
dnsop-nsec-ttl); proposed text and editorial changes are very much
welcomed there, but any functional changes should always first be
discussed on the IETF DNSOP WG mailing list.
]
[RFC2308] defines that the SOA TTL to be used in negative answers
(NXDOMAIN, NoData NOERROR) is
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| the minimum of the MINIMUM field of the SOA record and the TTL of
| the SOA itself
Thus, if the TTL of the SOA in the zone is lower than the SOA MINIMUM
value (the last number in a SOA record), the negative TTL for that
zone is lower than the SOA MINIMUM value.
However, [RFC4034] section 4 has this unfortunate text:
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