Network Working Group S. Bortzmeyer
Internet-Draft AFNIC
Intended status: Experimental February 2013
Expires: August 5, 2013

JSON format to represent DNS data


This document describes a profile of JSON to represent DNS data.

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Table of Contents

1. Introduction

The JavaScript Object Notation (JSON) format is specified in [RFC4627]. It is a structured data format suitable for a wide range of applications. It is specially popular on the Web, due to its JavaScript roots, but can be found in many other contexts.

The Domain Name System (DNS) is specified in [RFC1034] and [RFC1035]. It is one of the most important infrastructure components of the Internet. DNS data is today typically exchanged using two formats: the "zone file" format (partially) described in section 5 of [RFC1035] and the "wire format" of the section 4 for [RFC1035]. Other formats have been suggested, for an easier exchange of data, or for using DNS in new applications, such as DNS "looking glasses" or gateways to get DNS data over protocols such as HTTP ([RFC2616]).

For instance, a mechanism have been suggested for DNS data in XML, in [xml-data-schema].

This document suggests using the JSON format to represent DNS data.

2. Requirements notation

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].

3. The format

3.1. General rules

Most data is represented by JSON objects, with their named members. It is common to omit some of these members, to save bandwidth or by pure lazyness. So, clients who consume this sort of JSON objects should not assume every member is present. THIS IS AN IMPORTANT RULE (see Section 3.6, Paragraph 2 for a discussion).

3.2. Resource records

DNS resource records are JSON objects. The following members are common to all record types:

The other members depend on the record type. The following list gives the resource record type mnenomic and the JSON members for this type:

Note there is no concept of resource record sets (see Section 3.6, Paragraph 3 for a discussion).

3.3. DNS response

A DNS response is represented as a JSON object with a member named "Query". The main members of this object (the names are self-explanatory) are:

The Question Section is an object with members Qname, Qtype and Qclass. The other three sections are JSON arrays, each DNS record is an item in the array. They may be empty arrays (for instance, if the request returns NOERROR,ANSWER=0, the AnswerSection will be an empty array).

The Query object has members about the query: Duration is the time taken to process the request, Server the resolver used (preferably as an IP address).

3.4. Zone file

A DNS zone file is represented as a JSON object with a member named "Zone". The main member of this object is an array of resource records.

The member "Name" cannot be ommitted in resource records (unlike the text format of [RFC1035], JSON does not guarantee the order of records, so the trick of "previous resource record" does not work. But you can use relative names, and @ to denote the origin.

3.5. Examples

{"Query": {"Server": ""}, 
 "AnswerSection": [
       {"Name": "", 
        "MasterServerName": "", 
        "MaintainerName": "", "TTL": 3600, 
        "Serial": 2012060801, "Type": "SOA"}], 
 "ReturnCode": "NOERROR", 
 "AD": true, 
 "QuestionSection": {"Qtype": "SOA", "Qname": ""}}

An answer with a SOA resource record

{"Query": {"Duration": "0.167317", "Server": ""}, 
 "AnswerSection": [
    {"TTL": 6666, "Type": "AAAA", 
     "Address": "2a03:2880:10:8f01:face:b00c::25"}, 
    {"TTL": 6666, "Type": "AAAA", 
     "Address": "2a03:2880:2110:3f01:face:b00c::"}, 
    {"TTL": 6666, "Type": "AAAA", 
     "Address": "2a03:2880:10:1f02:face:b00c::25"}],
 "ReturnCode": "NOERROR"}

An answer with several resource records

{"Zone": {"Origin": ""},
     {"Type": "SOA", "Name": "@", 
      "MasterServerName": "venera", 
      "MaintainerName": "", 
      "Serial": 20},
     {"Type": "NS", Name": "@", 
      "Target": ""},
     {"Type": "NS", Name": "@", 
      "Target": "venera"},
     {"Type": "NS", Name": "@", 
      "Target": "vaxa"},
     {"Type": "MX", Name": "@", 
      "MailExchanger": "venera",
      "Preference": 10},
     {"Type": "MX", Name": "@", 
      "MailExchanger": "vaxa",
      "Preference": 20},
     {"Type": "A", Name": "a", 
      "Address": ""},
     {"Type": "A", Name": "venera", 
      "Address": ""},
     {"Type": "A", Name": "venera", 
      "Address": ""}

The zone file of RFC 1035

3.6. Open questions

Would it be a good idea to document a formal way to derive member names for the resource record JSON objects? It would allow 1) to document the rationale for the current names 2) to automatically allow representation of new DNS resource records.

Should we define mandatory members for some objects, in order to have something the consumers can rely on?

In resource records objects, members such as TTL are redundant (since they are actually RRset-wide). Should we have a new level of objects, for RRsets?

Should we use JSON schema ([json-schema]) to define the profile?

Should we add a normative reference to every RFC describing one of the RR types used here?

4. Security considerations

These JSON documents are not signed and therefore not authentified, even if the original data was secured with DNSSEC. If transported over an insecure transport, they can be read by a sniffer.

Also, see the security considerations of [RFC4627].

5. References

5.1. Normative References

[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987.
[RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, July 2006.

5.2. Informative References

[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[xml-data-schema] Parthasarath, M. and P. Vixie, "draft-mohan-dns-query-xml-00", September 2011.
[json-schema] Galiegue, F., Zyp, K. and G. Court, "draft-zyp-json-schema-04.txt: JSON Schema: core definitions and terminology", January 2013.

Author's Address

Stephane Bortzmeyer AFNIC Immeuble International Saint-Quentin-en-Yvelines, 78181 France Phone: +33 1 39 30 83 46 EMail: URI: