DNS Transport over TCP - Operational Requirements
draft-ietf-dnsop-dns-tcp-requirements-00
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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
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 December 22, 2017.
Copyright Notice
Copyright (c) 2017 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.
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
DNS standards were recently updated to declare support for TCP is now
a required part of the DNS implementation specifications in
[RFC7766]. This document is the formal requirements equivalent for
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