Internet Engineering Task Force H. Salgado Internet-Draft NIC Chile Intended status: Informational M. Vergara Ereche Expires: November 8, 2021 ICANN May 7, 2021 The "RRSERIAL" EDNS option for the SOA serial of a RR's zone draft-salgado-dnsop-rrserial-00 Abstract The "RRSERIAL" EDNS option allows a DNS querier to ask a DNS authoritative server to add a EDNS option in the answer of such query with the SOA serial number field of the origin zone which contains the answered resource record. This "RRSERIAL" data allows to debug problems and diagnosis by helping to recognize the origin of an answer, associating this answer with a respective zone version. 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 https://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 November 8, 2021. Copyright Notice Copyright (c) 2021 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 (https://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 Salgado & Vergara ErecheExpires November 8, 2021 [Page 1] Internet-Draft The RRSERIAL EDNS option May 2021 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. The RRSERIAL Option . . . . . . . . . . . . . . . . . . . . . 3 3. RRSERIAL Processing . . . . . . . . . . . . . . . . . . . . . 3 3.1. Querier . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Responder . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Example usage . . . . . . . . . . . . . . . . . . . . . . . . 3 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6.1. DNS EDNS0 Option Code Registration . . . . . . . . . . . 4 7. Security Considerations . . . . . . . . . . . . . . . . . . . 4 8. Normative References . . . . . . . . . . . . . . . . . . . . 4 Appendix A. Implementation References . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction The "RRSERIAL" EDNS option [RFC6891] allows a DNS querier to ask a DNS authoritative server to add a EDNS option in the answer of such query with the SOA serial number field of the zone which contains the answered resource record. This "RRSERIAL" data allows to debugging helping to recognize the origin of an answer, associating this answer with a respective zone version. The DNS data is of loose coherent nature, meaning that a record obtained by a response could be out-of-sync with other authoritative sources of the same data. This makes it difficult to debug the responses because you'd need to couple an answer with the version of the zone used to obtain such data. Even when you could use a separate question to ask for the SOA RR of the zone to ask for its serial, this separate question is in another time and could even arrive to another authoritative source, so it's not directly correlated with another query. This EDNS option is aimed only to authorative servers for a zone. Resolvers and forwarders should ignore the option. It's only intended for hop-to-hop communication (not transitive). Salgado & Vergara ErecheExpires November 8, 2021 [Page 2] Internet-Draft The RRSERIAL EDNS option May 2021 1.1. Requirements Language 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 [RFC2119]. 2. The RRSERIAL Option The OPTION-CODE for the RRSERIAL option is . The OPTION-DATA for the RRSERIAL option is an unsigned 32 bit version number as defined in the SERIAL field of the "SOA RDATA Format" section (3.3.13) of "DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION" (RFC 1035 [RFC1035]) specification. 3. RRSERIAL Processing 3.1. Querier The EDNS RRSERIAL option MAY be included on any QUERY, by adding a zero-length EDNS RRSERIAL option to the options field of the OPT record when the query is made. 3.2. Responder If an EDNS RRSERIAL option is sent to a server that is authoritative for the zone queried, and the RCODE for the answer is NOERROR, the OPTION-DATA MUST be a copy of the serial field of the SOA resource record of the zone which contains the resource record of the ANSWER section. Otherwise, the answer MUST NOT add an EDNS RRSERIAL option to the response. 4. Example usage Salgado & Vergara ErecheExpires November 8, 2021 [Page 3] Internet-Draft The RRSERIAL EDNS option May 2021 $ dig @auth_server www.example.com AAAA +rrserial +norec +nocmd ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16429 ;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ; RRSERIAL: 2019073001 ;; QUESTION SECTION: ;www.example.com. IN AAAA ;; ANSWER SECTION: www.example.com. 900 IN AAAA ;; Query time: 53 msec ;; SERVER: authoritative#53(2001:DB8::53) ;; WHEN: Tue Aug 07 16:54:05 -04 2018 ;; MSG SIZE rcvd: 71 5. Acknowledgements This document was made by his author in its entirety, so there're no acknowledgements yet. 6. IANA Considerations 6.1. DNS EDNS0 Option Code Registration Ask to IANA for a code point registration for "RRSERIAL" option. 7. Security Considerations There's no risk on disclosure of private information, as the SERIAL of the SOA record is already publicly available. 8. Normative References [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, November 1987, . Salgado & Vergara ErecheExpires November 8, 2021 [Page 4] Internet-Draft The RRSERIAL EDNS option May 2021 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms for DNS (EDNS(0))", STD 75, RFC 6891, DOI 10.17487/RFC6891, April 2013, . Appendix A. Implementation References There's a patched NSD server 4.1.23 with support for RRSERIAL with the experimental opcode 65024 maintained in github https://github.com/huguei/nsd/tree/rrserial , and installed for live testing in 200.1.122.30 address with configured zones dateserial.example.com and incserial.example.com; with MX, TXT and AAAA apex records. Authors' Addresses Hugo Salgado NIC Chile Miraflores 222, piso 14 Santiago CP 8320198 CL Phone: +56 2 29407700 Email: hsalgado@nic.cl Mauricio Vergara Ereche ICANN Email: mauricio.vergara@icann.org Salgado & Vergara ErecheExpires November 8, 2021 [Page 5]