DNS Transport over TCP - Implementation Requirements
draft-ietf-dnsop-5966bis-00

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Document Type Active Internet-Draft (dnsop WG)
Authors John Dickinson  , Ray Bellis  , Allison Mankin  , Duane Wessels 
Last updated 2014-12-04
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dnsop                                                       J. Dickinson
Internet-Draft                             Sinodun Internet Technologies
Updates: 5966 (if approved)                                    R. Bellis
Intended status: Standards Track                                 Nominet
Expires: June 7, 2015                                          A. Mankin
                                                              D. Wessels
                                                           Verisign Labs
                                                        December 4, 2014

          DNS Transport over TCP - Implementation Requirements
                      draft-ietf-dnsop-5966bis-00

Abstract

   This document updates the requirements for the support of TCP as a
   transport protocol for DNS implementations.

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 June 7, 2015.

Copyright Notice

   Copyright (c) 2014 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

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Transport Protocol Selection  . . . . . . . . . . . . . . . .   4
   5.  Connection Handling . . . . . . . . . . . . . . . . . . . . .   5
   6.  Query Pipelining  . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Response Reordering . . . . . . . . . . . . . . . . . . . . .   6
   8.  TCP Fast Open . . . . . . . . . . . . . . . . . . . . . . . .   7
   9.  Summary of Advantages and Disadvantages to using TCP for DNS    8
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   11. Security Considerations . . . . . . . . . . . . . . . . . . .   9
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     13.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     13.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Appendix A.  Changes to RFC 5966  . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Most DNS [RFC1034] transactions take place over UDP [RFC0768].  TCP
   [RFC0793] is always used for full zone transfers (AXFR) and is often
   used for messages whose sizes exceed the DNS protocol's original
   512-byte limit.

   Section 6.1.3.2 of [RFC1123] states:

      DNS resolvers and recursive servers MUST support UDP, and SHOULD
      support TCP, for sending (non-zone-transfer) queries.

   However, some implementors have taken the text quoted above to mean
   that TCP support is an optional feature of the DNS protocol.

   The majority of DNS server operators already support TCP and the
   default configuration for most software implementations is to support
   TCP.  The primary audience for this document is those implementors
   whose failure to support TCP restricts interoperability and limits
   deployment of new DNS features.

   This document therefore updates the core DNS protocol specifications
   such that support for TCP is henceforth a REQUIRED part of a full DNS
   protocol implementation.

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   There are several advantages and disadvantages to the increased use
   of TCP as well as implementation details that need to be considered.
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