DNS Multiple QTYPEs
draft-bellis-dnsext-multi-qtypes-03

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Last updated 2016-10-26
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DNSEXT Working Group                                           R. Bellis
Internet-Draft                                                       ISC
Intended status: Standards Track                        October 26, 2016
Expires: April 29, 2017

                          DNS Multiple QTYPEs
                  draft-bellis-dnsext-multi-qtypes-03

Abstract

   This document specifies a method for a DNS client to request
   additional DNS record types to be delivered alongside the primary
   record type specified in the question section of a DNS query.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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

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Bellis                   Expires April 29, 2017                 [Page 1]
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology used in this document . . . . . . . . . . . . . .   3
   3.  Description . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Multiple QTYPE EDNS Option Format . . . . . . . . . . . .   3
     3.2.  Response Generation . . . . . . . . . . . . . . . . . . .   4
       3.2.1.  Server Side Processing  . . . . . . . . . . . . . . .   4
       3.2.2.  Client Side Processing  . . . . . . . . . . . . . . .   5
       3.2.3.  DNSSEC  . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   A commonly requested DNS [RFC1035] feature is the ability to receive
   multiple related resource records (RRs) in a single DNS response.

   For example, it may be desirable to receive both the A and AAAA
   records for a domain name together, rather than having to issue
   multiple queries.

   The DNS wire protocol in theory supports having multiple questions in
   a single packet, but in practise this does not work:

   o  Each question consists of the tuple (QNAME, QTYPE, QCLASS).  Since
      each question has its own QNAME field it would be possible for one
      name to exist and another to not exist, resulting in an
      inconsistent response code.

   o  The idea that only a single question is allowed is sufficiently
      entrenched that many DNS servers will simply return an error (or
      fail to response at all) if they receive a query with a question
      count (QDCOUNT) of more than one.

   To resolve both of these issues, this document constraints the
   problem to those cases where only the QTYPE varies by specifying a
   new option for the Extension Mechanisms for DNS (EDNS [RFC6891]) that
   contains an additional list of QTYPE values that the client wishes to
   receive in addition to that in the primary question.

   TODO: why not "ANY" ?

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2.  Terminology used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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