NSEC(3) TTLs and NSEC Aggressive Use
draft-ietf-dnsop-nsec-ttl-00

Document Type Active Internet-Draft (dnsop WG)
Author Peter van Dijk 
Last updated 2021-01-13
Replaces draft-vandijk-dnsop-nsec-ttl
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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

   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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 17 July 2021.

Copyright Notice

   Copyright (c) 2021 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
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   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

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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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