Extension Mechanisms for DNS (EDNS(0))
RFC 6891
Document | Type |
RFC - Internet Standard
(April 2013; Errata)
Also known as STD 75
|
|
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Authors | João Damas , Michael Graff , Paul Vixie | ||
Last updated | 2020-01-21 | ||
Replaces | draft-graff-dnsext-edns0bis | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized with errata bibtex | ||
Reviews | |||
Stream | WG state | Waiting for WG Chair Go-Ahead | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 6891 (Internet Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Ralph Droms | ||
IESG note | Olafur Gudmundsson (ogud at ogud.com) is the document shepherd. | ||
Send notices to | (None) |
Internet Engineering Task Force (IETF) J. Damas Request for Comments: 6891 Bond Internet Systems STD: 75 M. Graff Obsoletes: 2671, 2673 Category: Standards Track P. Vixie ISSN: 2070-1721 Internet Systems Consortium April 2013 Extension Mechanisms for DNS (EDNS(0)) Abstract The Domain Name System's wire protocol includes a number of fixed fields whose range has been or soon will be exhausted and does not allow requestors to advertise their capabilities to responders. This document describes backward-compatible mechanisms for allowing the protocol to grow. This document updates the Extension Mechanisms for DNS (EDNS(0)) specification (and obsoletes RFC 2671) based on feedback from deployment experience in several implementations. It also obsoletes RFC 2673 ("Binary Labels in the Domain Name System") and adds considerations on the use of extended labels in the DNS. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6891. Damas, et al. Standards Track [Page 1] RFC 6891 EDNS(0) Extensions April 2013 Copyright Notice Copyright (c) 2013 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. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Damas, et al. Standards Track [Page 2] RFC 6891 EDNS(0) Extensions April 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. EDNS Support Requirement . . . . . . . . . . . . . . . . . . . 5 4. DNS Message Changes . . . . . . . . . . . . . . . . . . . . . 5 4.1. Message Header . . . . . . . . . . . . . . . . . . . . . . 5 4.2. Label Types . . . . . . . . . . . . . . . . . . . . . . . 5 4.3. UDP Message Size . . . . . . . . . . . . . . . . . . . . . 6 5. Extended Label Types . . . . . . . . . . . . . . . . . . . . . 6 6. The OPT Pseudo-RR . . . . . . . . . . . . . . . . . . . . . . 6 6.1. OPT Record Definition . . . . . . . . . . . . . . . . . . 6 6.1.1. Basic Elements . . . . . . . . . . . . . . . . . . . . 6 6.1.2. Wire Format . . . . . . . . . . . . . . . . . . . . . 7 6.1.3. OPT Record TTL Field Use . . . . . . . . . . . . . . . 9 6.1.4. Flags . . . . . . . . . . . . . . . . . . . . . . . . 9 6.2. Behaviour . . . . . . . . . . . . . . . . . . . . . . . . 10 6.2.1. Cache Behaviour . . . . . . . . . . . . . . . . . . . 10 6.2.2. Fallback . . . . . . . . . . . . . . . . . . . . . . . 10 6.2.3. Requestor's Payload Size . . . . . . . . . . . . . . . 10 6.2.4. Responder's Payload Size . . . . . . . . . . . . . . . 11 6.2.5. Payload Size Selection . . . . . . . . . . . . . . . . 11 6.2.6. Support in Middleboxes . . . . . . . . . . . . . . . . 11Show full document text