Serving Stale Data to Improve DNS Resiliency
draft-tale-dnsop-serve-stale-01

Document Type Active Internet-Draft (dnsop WG)
Last updated 2017-07-30 (latest revision 2017-06-27)
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DNSOP Working Group                                          D. Lawrence
Internet-Draft                                       Akamai Technologies
Updates: 1034, 1035 (if approved)                              W. Kumari
Intended status: Standards Track                                  Google
Expires: December 29, 2017                                 June 27, 2017

              Serving Stale Data to Improve DNS Resiliency
                    draft-tale-dnsop-serve-stale-01

Abstract

   This draft defines a method for recursive resolvers to use stale DNS
   data to avoid outages when authoritative nameservers cannot be
   reached to refresh expired data.

Ed note

   Text inside square brackets ([]) is additional background
   information, answers to frequently asked questions, general musings,
   etc.  They will be removed before publication.  This document is
   being collaborated on in GitHub at <https://github.com/vttale/serve-
   stale>.  The most recent version of the document, open issues, etc
   should all be available here.  The authors gratefully accept pull
   requests.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 29, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Lawrence & Kumari       Expires December 29, 2017               [Page 1]
Internet-Draft               DNS Serve Stale                   June 2017

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Description . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Implementation Caveats  . . . . . . . . . . . . . . . . . . .   4
   5.  Implementation Status . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   6
   8.  NAT Considerations  . . . . . . . . . . . . . . . . . . . . .   6
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     11.1.  Normative References . . . . . . . . . . . . . . . . . .   6
     11.2.  Informative References . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Traditionally the Time To Live (TTL) of a DNS resource record has
   been understood to represent the maximum number of seconds that a
   record can be used before it must be discarded, based on its
   description and usage in [RFC1035] and clarifications in [RFC2181].
   Specifically, [RFC1035] Section 3.2.1 says that it "specifies the
   time interval that the resource record may be cached before the
   source of the information should again be consulted".

   Notably, the original DNS specification does not say that data past
   its expiration cannot be used.  This document proposes a method for
   how recursive resolvers should handle stale DNS data to balance the
   competing needs of resiliency and freshness.  It is predicated on the
   observation that authoritative server unavailability can cause
   outages even when the underlying data those servers would return is
   typically unchanged.

   There are a number of reasons why an authoritative server may become
   unreachable, including Denial of Service (DoS) attacks, network
   issues, and so on.  This document suggests that, if the recursive
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