Network Working Group P. Spacek
Internet-Draft CZ.NIC
Intended status: Standards Track O. Gudmundsson
Expires: September 20, 2018 Cloudflare
O. Sury
ISC
March 19, 2018

Minimal EDNS compliance requirements
draft-spacek-edns-camel-diet-00

Abstract

DNS responders must either follow RFC 6891 by implementing EDNS or respond with RCODE=FORMERR to queries containing OPT record. Non-compliant implementations are not worth talking to.

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Table of Contents

1. Introduction

EDNS version 0 was standardized in 1999, but non-RFC 1035 compliant implementations still exist and cause lot of extra queries and complicated logic in recursive resolvers. RFC 6891 clearly states that FORMERR is the only acceptable answer for implementations without support for EDNS. The cost of supporting these non-compliant implementations keeps increasing.

1.1. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

2. The Protocol

No DNS response message to a repeated DNS query containing EDNS extension means that the other side is not a DNS responder and the querier MUST NOT retry its query without EDNS.

3. Security Considerations

Instruction to follow EDNS standard does not change security properties beyond what is written in RFC 6891.

4. Privacy Considerations

This has no effect on privacy of DNS.

5. IANA Considerations

[Note to IANA, to be removed prior to publication: there are no IANA considerations stated in this version of the document.]

6. Normative References

[RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, November 1987.
[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC 2671, DOI 10.17487/RFC2671, August 1999.
[RFC6891] Damas, J., Graff, M. and P. Vixie, "Extension Mechanisms for DNS (EDNS(0))", STD 75, RFC 6891, DOI 10.17487/RFC6891, April 2013.

Authors' Addresses

Petr Spacek EMail: petr.spacek@nic.cz
Olafur Gudmundsson EMail: olafur+ietf@cloudflare.com
Ondrej Sury EMail: ondrej@isc.org