Delegation Revalidation by DNS Resolvers
draft-huque-dnsop-ns-revalidation-00

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Internet Engineering Task Force                                 S. Huque
Internet-Draft                                                Salesforce
Intended status: Standards Track                                P. Vixie
Expires: May 7, 2020                                   Farsight Security
                                                        November 4, 2019

                Delegation Revalidation by DNS Resolvers
                  draft-huque-dnsop-ns-revalidation-00

Abstract

   This document recommends improved DNS [RFC1034] [RFC1035] resolver
   behavior with respect to the processing of Name Server (NS) resource
   record sets (RRset) during iterative resolution.  When following a
   referral response from an authoritative server to a child zone, DNS
   resolvers should explicitly query the authoritative NS RRset at the
   apex of the child zone and cache this in preference to the NS RRset
   on the parent side of the zone cut.  Resolvers should also
   periodically revalidate the child delegation by re-quering the parent
   zone at the expiration of the TTL of the parent side NS RRset.

Status of This Memo

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   This Internet-Draft will expire on May 7, 2020.

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   This document is subject to BCP 78 and the IETF Trust's Legal
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Huque & Vixie              Expires May 7, 2020                  [Page 1]
Internet-Draft           Delegation Revalidation           November 2019

   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Upgrading NS RRset Credibility  . . . . . . . . . . . . . . .   4
   4.  Delegation Revalidation . . . . . . . . . . . . . . . . . . .   4
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   This document recommends improved DNS resolver behavior with respect
   to the processing of NS record sets during iterative resolution.  The
   first recommendation is that resolvers, when following a referral
   response from an authoritative server to a child zone, should
   explicitly query the authoritative NS RRset at the apex of the child
   zone and cache this in preference to the NS RRset on the parent side
   of the zone cut.  The second recommendation is to revalidate the
   delegation by re-quering the parent zone at the expiration of the TTL
   of the parent side NS RRset.

2.  Motivation

   The delegation NS RRset at the bottom of the parent zone and the apex
   NS RRset in the child zone are unsynchronized in the DNS protocol.
   [RFC1034] Section 4.2.2 says "The administrators of both zones should
   insure that the NS and glue RRs which mark both sides of the cut are
   consistent and remain so.".  But for a variety of reasons they could
   not be.  Officially, a child zone's apex NS RRset is authoritative
   and thus has a higher cache credibility than the parent's delegation
   NS RRset, which is non-authoritative glue ([RFC2181], Section 5.4.1.
   Ranking data).  Hence the NS RRset "below the zone cut" should
   immediately replace the parent's delegating NS RRset in cache when an
   iterative caching DNS resolver crosses a zone boundary.  However,
   this can only happen if (1) the resolver receives the authoritative
   NS RRset in the Authority section of a response from the child zone,
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