Dynamic DNS Update Leases

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Last updated 2018-08-02
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Internet Engineering Task Force                              S. Cheshire
Internet-Draft                                                Apple Inc.
Intended status: Standards Track                                T. Lemon
Expires: February 2, 2019                            Nibbhaya Consulting
                                                          August 1, 2018

                       Dynamic DNS Update Leases


   This document proposes a method of extending Dynamic DNS Update to
   contain an update lease lifetime, allowing a server to garbage
   collect stale resource records.

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
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   This Internet-Draft will expire on February 2, 2019.

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   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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1.  Introduction

   Dynamic DNS Update [RFC2136] allows for a mapping from a persistent
   hostname to a dynamic IP address.  This capability is particularly
   beneficial to mobile hosts, whose IP address may frequently change
   with location.  However, the mobile nature of such hosts often means
   that dynamically updated resource records are not properly deleted.
   Consider, for instance, a mobile user who publishes address records
   via dynamic update.  If this user moves their laptop out of range of
   the Wi-Fi access point, the address record containing stale
   information may remain on the server indefinitely.  An extension to
   Dynamic Update is thus required to tell the server to automatically
   delete resource records if they are not refreshed after a period of

   Note that overloading the resource record TTL [RFC1035] is not
   appropriate for purposes of garbage collection.  Data that is
   susceptible to frequent change or invalidation, thus requiring a
   garbage collection mechanism, needs a relatively short resource
   record TTL to avoid polluting intermediate DNS caches with stale
   data.  Using this TTL, short enough to minimize stale cached data, as
   a garbage collection lease lifetime would result in an unacceptable
   amount of network traffic due to refreshes (see Section 5 "Refresh

2.  Conventions and Terminology Used in this Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   and "OPTIONAL" in this document are to be interpreted as described
   in "Key words for use in RFCs to Indicate Requirement Levels",
   when, and only when, they appear in all capitals, as shown here
   [RFC2119] [RFC8174].

3.  Mechanisms

   Dynamic DNS Update Leases is implemented using the standard Dynamic
   Update message format [RFC2136] in conjunction with an EDNS(0) OPT
   pseudo-RR [RFC6891] with a new OPT and RDATA format proposed here.
   Encoding the Update Lease Lifetime in an OPT RR requires minimal
   modification to a name server's front-end, and will cause servers
   that do not implement this extension to automatically return a
   descriptive error (NOTIMPL).

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4.  Update Message Format

   Dynamic DNS Update Leases Requests and Responses are formatted as
   standard DNS Dynamic Update messages [RFC2136], with the addition of
   a single OPT RR in the Additional section.  Note that if a TSIG
   resource record is to be added to authenticate the update [RFC2845],
   the TSIG RR should appear *after* the OPT RR, allowing the message
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