Serving Stale Data to Improve DNS Resiliency
draft-ietf-dnsop-serve-stale-05
DNSOP Working Group D. Lawrence
Internet-Draft Oracle
Updates: 1034, 1035 (if approved) W. Kumari
Intended status: Standards Track P. Sood
Expires: October 18, 2019 Google
April 16, 2019
Serving Stale Data to Improve DNS Resiliency
draft-ietf-dnsop-serve-stale-05
Abstract
This draft defines a method (serve-stale) for recursive resolvers to
use stale DNS data to avoid outages when authoritative nameservers
cannot be reached to refresh expired data. It updates the definition
of TTL from [RFC1034], [RFC1035], and [RFC2181] to make it clear that
data can be kept in the cache beyond the TTL expiry and used for
responses when a refreshed answer is not readily available. One of
the motivations for serve-stale is to make the DNS more resilient to
DoS attacks, and thereby make them less attractive as an attack
vector.
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 https://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."
Lawrence, et al. Expires October 18, 2019 [Page 1]
Internet-Draft DNS Serve Stale April 2019
This Internet-Draft will expire on October 18, 2019.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Standards Action . . . . . . . . . . . . . . . . . . . . . . 4
5. Example Method . . . . . . . . . . . . . . . . . . . . . . . 4
6. Implementation Considerations . . . . . . . . . . . . . . . . 6
7. Implementation Caveats . . . . . . . . . . . . . . . . . . . 8
8. Implementation Status . . . . . . . . . . . . . . . . . . . . 9
9. EDNS Option . . . . . . . . . . . . . . . . . . . . . . . . . 10
10. Security Considerations . . . . . . . . . . . . . . . . . . . 10
11. Privacy Considerations . . . . . . . . . . . . . . . . . . . 10
12. NAT Considerations . . . . . . . . . . . . . . . . . . . . . 11
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
15.1. Normative References . . . . . . . . . . . . . . . . . . 11
15.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
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].
This document proposes that the definition of the TTL be explicitly
expanded to allow for expired data to be used in the exceptional
circumstance that a recursive resolver is unable to refresh the
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