Extension Mechanisms for DNS (EDNS) EXPIRE Option
RFC 7314
Document | Type |
RFC - Experimental
(July 2014; No errata)
Was draft-andrews-dnsext-expire (individual)
|
|
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Author | Mark Andrews | ||
Last updated | 2014-07-17 | ||
Stream | ISE | ||
Formats | plain text html pdf htmlized bibtex | ||
IETF conflict review | conflict-review-andrews-dnsext-expire | ||
Stream | ISE state | Published RFC | |
Consensus Boilerplate | Unknown | ||
Document shepherd | Adrian Farrel | ||
Shepherd write-up | Show (last changed 2014-03-27) | ||
IESG | IESG state | RFC 7314 (Experimental) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) | ||
IANA | IANA review state | IANA OK - Actions Needed | |
IANA action state | RFC-Ed-Ack |
Independent Submission M. Andrews Request for Comments: 7314 ISC Category: Experimental July 2014 ISSN: 2070-1721 Extension Mechanisms for DNS (EDNS) EXPIRE Option Abstract This document specifies a method for secondary DNS servers to honour the SOA EXPIRE field as if they were always transferring from the primary, even when using other secondaries to perform indirect transfers and refresh queries. Status of This Memo This document is not an Internet Standards Track specification; it is published for examination, experimental implementation, and evaluation. This document defines an Experimental Protocol for the Internet community. This is a contribution to the RFC Series, independently of any other RFC stream. The RFC Editor has chosen to publish this document at its discretion and makes no statement about its value for implementation or deployment. Documents approved for publication by the RFC Editor are not a candidate for any level of Internet Standard; see 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/rfc7314. 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. Andrews Experimental [Page 1] RFC 7314 Extension Mechanisms for DNS (EDNS) EXPIRE Option July 2014 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Reserved Words . . . . . . . . . . . . . . . . . . . . . 2 2. Expire EDNS Option (Query) . . . . . . . . . . . . . . . . . 3 3. Expire EDNS Option (Response) . . . . . . . . . . . . . . . . 3 3.1. Primary Server . . . . . . . . . . . . . . . . . . . . . 3 3.2. Secondary Server . . . . . . . . . . . . . . . . . . . . 3 3.3. Non-authoritative Server . . . . . . . . . . . . . . . . 3 4. Secondary Behaviour . . . . . . . . . . . . . . . . . . . . . 3 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 7. Normative References . . . . . . . . . . . . . . . . . . . . 4 1. Introduction The expire field of a DNS zone's SOA record [RFC1035] is supposed to indicate when a secondary server shall discard the contents of the zone when it has been unable to contact the primary [RFC1034]. Current practice only works when all the secondaries contact the primary directly to perform refresh queries and zone transfers. While secondaries are expected to be able to, and often are configured to, transfer from other secondaries for robustness reasons as well as reachability constraints, there is no mechanism provided to preserve the expiry behaviour when using a secondary. Instead, secondaries have to know whether they are talking directly to the primary or another secondary and use that to decide whether or not to update the expire timer. This, however, fails to take into account delays in transferring from one secondary to another. There are also zone-transfer graphs in which the secondary never talks to the primary, so the effective expiry period becomes multiplied by the length of the zone-transfer graph, which is infinite when it contains loops. This document provides a mechanism to preserve the expiry behaviour regardless of what zone-transfer graph is constructed and whether the secondary is talking to the primary or another secondary. 1.1. Reserved Words 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 [RFC2119]. Andrews Experimental [Page 2] RFC 7314 Extension Mechanisms for DNS (EDNS) EXPIRE Option July 2014 2. Expire EDNS Option (Query) The EDNS [RFC6891] EXPIRE option has the value <9>. The EDNS EXPIRE option MAY be included on any QUERY, though usually this is only done on SOA, AXFR, and IXFR queries involved in zone maintenance. This is done by adding a zero-length EDNS EXPIRE option to the options field of the OPT record when the query is made. 3. Expire EDNS Option (Response) 3.1. Primary Server When the query is directed to the primary server for the zone, theShow full document text