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Salgado 3 Internet-Draft NIC Chile 4 Intended status: Informational January 27, 2020 5 Expires: July 30, 2020 7 The "RRSERIAL" EDNS option for the SOA serial of a RR's zone 8 draft-salgado-rrserial-01 10 Abstract 12 The "RRSERIAL" EDNS option allows a DNS querier to ask a DNS 13 authoritative server to add a EDNS option in the answer of such query 14 with the SOA serial number field of the origin zone which contains 15 the answered resource record. 17 This "RRSERIAL" data allows to debug problems and diagnosis by 18 helping to recognize the origin of an answer, associating this answer 19 with a respective zone version. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at https://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on July 30, 2020. 38 Copyright Notice 40 Copyright (c) 2020 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (https://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 57 2. The RRSERIAL Option . . . . . . . . . . . . . . . . . . . . . 3 58 3. RRSERIAL Processing . . . . . . . . . . . . . . . . . . . . . 3 59 3.1. Querier . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 3.2. Responder . . . . . . . . . . . . . . . . . . . . . . . . 3 61 4. Example usage . . . . . . . . . . . . . . . . . . . . . . . . 3 62 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 63 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 64 6.1. DNS EDNS0 Option Code Registration . . . . . . . . . . . 4 65 7. Security Considerations . . . . . . . . . . . . . . . . . . . 4 66 8. Normative References . . . . . . . . . . . . . . . . . . . . 4 67 Appendix A. Implementation References . . . . . . . . . . . . . 5 68 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 70 1. Introduction 72 The "RRSERIAL" EDNS option [RFC6891] allows a DNS querier to ask a 73 DNS authoritative server to add a EDNS option in the answer of such 74 query with the SOA serial number field of the zone which contains the 75 answered resource record. 77 This "RRSERIAL" data allows to debugging helping to recognize the 78 origin of an answer, associating this answer with a respective zone 79 version. 81 The DNS data is of loose coherent nature, meaning that a record 82 obtained by a response could be out-of-sync with other authoritative 83 sources of the same data. This makes it difficult to debug the 84 responses because you'd need to couple an answer with the version of 85 the zone used to obtain such data. Even when you could use a 86 separate question to ask for the SOA RR of the zone to ask for its 87 serial, this separate question is in another time and could even 88 arrive to another authoritative source, so it's not directly 89 correlated with another query. 91 This EDNS option is aimed only to authorative servers for a zone. 92 Resolvers and forwarders should ignore the option. It's only 93 intended for hop-to-hop communication (not transitive). 95 1.1. Requirements Language 97 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 98 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 99 document are to be interpreted as described in RFC 2119 [RFC2119]. 101 2. The RRSERIAL Option 103 The OPTION-CODE for the RRSERIAL option is . 105 The OPTION-DATA for the RRSERIAL option is an unsigned 32 bit version 106 number as defined in the SERIAL field of the "SOA RDATA Format" 107 section (3.3.13) of "DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION" 108 (RFC 1035 [RFC1035]) specification. 110 3. RRSERIAL Processing 112 3.1. Querier 114 The EDNS RRSERIAL option MAY be included on any QUERY, by adding a 115 zero-length EDNS RRSERIAL option to the options field of the OPT 116 record when the query is made. 118 3.2. Responder 120 If an EDNS RRSERIAL option is sent to a server that is authoritative 121 for the zone queried, and the RCODE for the answer is NOERROR, the 122 OPTION-DATA MUST be a copy of the serial field of the SOA resource 123 record of the zone which contains the resource record of the ANSWER 124 section. 126 Otherwise, the answer MUST NOT add an EDNS RRSERIAL option to the 127 response. 129 4. Example usage 130 $ dig @auth_server www.example.com AAAA +rrserial +norec +nocmd 132 ; (1 server found) 133 ;; global options: +cmd 134 ;; Got answer: 135 ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16429 136 ;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 138 ;; OPT PSEUDOSECTION: 139 ; EDNS: version: 0, flags:; udp: 4096 140 ; RRSERIAL: 2019073001 141 ;; QUESTION SECTION: 142 ;www.example.com. IN AAAA 144 ;; ANSWER SECTION: 145 www.example.com. 900 IN AAAA 147 ;; Query time: 53 msec 148 ;; SERVER: authoritative#53(2001:DB8::53) 149 ;; WHEN: Tue Aug 07 16:54:05 -04 2018 150 ;; MSG SIZE rcvd: 71 152 5. Acknowledgements 154 This document was made by his author in its entirety, so there're no 155 acknowledgements yet. 157 6. IANA Considerations 159 6.1. DNS EDNS0 Option Code Registration 161 Ask to IANA for a code point registration for "RRSERIAL" option. 163 7. Security Considerations 165 There's no risk on disclosure of private information, as the SERIAL 166 of the SOA record is already publicly available. 168 8. Normative References 170 [RFC1035] Mockapetris, P., "Domain names - implementation and 171 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 172 November 1987, . 174 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 175 Requirement Levels", BCP 14, RFC 2119, 176 DOI 10.17487/RFC2119, March 1997, 177 . 179 [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms 180 for DNS (EDNS(0))", STD 75, RFC 6891, 181 DOI 10.17487/RFC6891, April 2013, 182 . 184 Appendix A. Implementation References 186 There's a patched NSD server 4.1.23 with support for RRSERIAL with 187 the experimental opcode 65024 maintained in github 188 https://github.com/huguei/nsd/tree/rrserial , and installed for live 189 testing in 200.1.122.30 address with configured zones 190 dateserial.example.com and incserial.example.com; with MX, TXT and 191 AAAA apex records. 193 Author's Address 195 Hugo Salgado 196 NIC Chile 197 Miraflores 222, piso 14 198 Santiago CP 8320198 199 CL 201 Phone: +56 2 29407700 202 Email: hsalgado@nic.cl