DNS Transport over TCP - Operational Requirements
draft-ietf-dnsop-dns-tcp-requirements-00

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Last updated 2017-06-20
Replaces draft-kristoff-dnsop-dns-tcp-requirements
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Domain Name System Operations                                J. Kristoff
Internet-Draft                                         DePaul University
Intended status: Best Current Practice                        D. Wessels
Expires: December 22, 2017                                      Verisign
                                                           June 20, 2017

           DNS Transport over TCP - Operational Requirements
                draft-ietf-dnsop-dns-tcp-requirements-00

Abstract

   This document encourages the practice of permitting DNS messages to
   be carried over TCP on the Internet.  It also describes some of the
   consequences of this behavior and the potential operational issues
   that can arise when this best common practice is not upheld.

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 December 22, 2017.

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   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Kristoff & Wessels      Expires December 22, 2017               [Page 1]
Internet-Draft           DNS Transport over TCP                June 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Uneven Transport Usage and Preference . . . . . . . . . .   3
     2.2.  Waiting for Large Messages and Reliability  . . . . . . .   3
     2.3.  EDNS0 . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.4.  "Only Zone Tranfers Use TCP"  . . . . . . . . . . . . . .   5
   3.  DNS over TCP Requirements . . . . . . . . . . . . . . . . . .   5
   4.  Network and System Considerations . . . . . . . . . . . . . .   6
   5.  DNS over TCP Filtering Risks  . . . . . . . . . . . . . . . .   6
     5.1.  DNS Wedgie  . . . . . . . . . . . . . . . . . . . . . . .   6
     5.2.  DNS Root Zone KSK Rollover  . . . . . . . . . . . . . . .   6
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Standards Related to DNS Transport over TCP  . . . .  10
     A.1.  TODO - additional, relevant RFCs  . . . . . . . . . . . .  10
     A.2.  IETF RFC 7477 - Child-to-Parent Synchronization in DNS  .  11
     A.3.  IETF RFC 7766 - DNS Transport over TCP - Implementation
           Requirements  . . . . . . . . . . . . . . . . . . . . . .  11
     A.4.  IETF RFC 7828 - The edns-tcp-keepalive EDNS0 Option . . .  11
     A.5.  IETF RFC 7873 - Domain Name System (DNS) Cookies  . . . .  11
     A.6.  IETF RFC 7901 - CHAIN Query Requests in DNS . . . . . . .  11
     A.7.  IETF RFC 8027 - DNSSEC Roadblock Avoidance  . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   DNS messages may be delivered using UDP or TCP communications.  While
   most DNS transactions are carried over UDP, some operators have been
   led to believe that any DNS over TCP traffic is unwanted or
   unnecessary for general DNS operation.  As usage and features have
   evolved, TCP transport has become increasingly important for correct
   and safe operation of the Internet DNS.  Reflecting modern usage, the
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