DNS Multiple QTYPEs
draft-bellis-dnsext-multi-qtypes-06
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DNSEXT Working Group R. Bellis
Internet-Draft ISC
Intended status: Standards Track July 02, 2018
Expires: January 3, 2019
DNS Multiple QTYPEs
draft-bellis-dnsext-multi-qtypes-06
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.
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 January 3, 2019.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Bellis Expires January 3, 2019 [Page 1]
Internet-Draft DNS Multiple QTYPEs July 2018
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 . . . . . . . . . . . . . . . . . . . . . . 6
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" ?
Bellis Expires January 3, 2019 [Page 2]
Internet-Draft DNS Multiple QTYPEs July 2018
2. Terminology used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Description
3.1. Multiple QTYPE EDNS Option Format
The overall format of an EDNS option is shown for reference below,
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