Tech-invite3GPPspecsGlossariesIETFRFCsGroupsSIPABNFsWorld Map

RFC 8427

[Errata]
Informational
Pages: 15
Top     in Index     Prev     Next
in Group Index     Prev in Group     No Next: Highest Number in Group     Group: ~dns

Representing DNS Messages in JSON

 


Top       ToC       Page 1 
Internet Engineering Task Force (IETF)                        P. Hoffman
Request for Comments: 8427                                         ICANN
Category: Informational                                        July 2018
ISSN: 2070-1721


                   Representing DNS Messages in JSON

Abstract

   Some applications use DNS messages, or parts of DNS messages, as
   data.  For example, a system that captures DNS queries and responses
   might want to be able to easily search them without having to decode
   the messages each time.  Another example is a system that puts
   together DNS queries and responses from message parts.  This document
   describes a general format for DNS message data in JSON.  Specific
   profiles of the format in this document can be described in other
   documents for specific applications and usage scenarios.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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).  Not all documents
   approved by the IESG are candidates for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8427.

Top      ToC       Page 2 
Copyright Notice

   Copyright (c) 2018 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
   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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Design of the Format  . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
   2.  JSON Format for DNS Messages  . . . . . . . . . . . . . . . .   5
     2.1.  Message Object Members  . . . . . . . . . . . . . . . . .   5
     2.2.  Resource Record Object Members  . . . . . . . . . . . . .   6
     2.3.  Specific RDATA Field Members  . . . . . . . . . . . . . .   7
     2.4.  The Message and Its Parts as Octets . . . . . . . . . . .   8
     2.5.  Additional Message Object Members . . . . . . . . . . . .   8
     2.6.  Name Fields . . . . . . . . . . . . . . . . . . . . . . .   9
   3.  JSON Format for a Paired DNS Query and Response . . . . . . .   9
   4.  Streaming DNS Objects . . . . . . . . . . . . . . . . . . . .   9
   5.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  10
     5.1.  Example of the Format of a DNS Query  . . . . . . . . . .  10
     5.2.  Example of the Format of a Paired DNS Query and Response   11
   6.  Local Format Policy . . . . . . . . . . . . . . . . . . . . .  12
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
     7.1.  Media Type Registration of application/dns+json . . . . .  12
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   9.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  14
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     10.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  15
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  15

Top      ToC       Page 3 
1.  Introduction

   The DNS message format is defined in [RFC1035].  DNS queries and DNS
   responses have exactly the same structure.  Many of the field names
   and data type names given in [RFC1035] are commonly used in
   discussions of DNS.  For example, it is common to hear things like
   "the query had a QNAME of 'example.com'" or "the RDATA has a simple
   structure".

   There are hundreds of data-interchange formats for serializing
   structured data.  Currently, JSON [RFC8259] is quite popular for many
   types of data, particularly data that has named subfields and
   optional parts.

   This document uses JSON to describe DNS messages.  It also defines
   how to describe a paired DNS query and response and how to stream DNS
   objects.

1.1.  Design of the Format

   There are many ways to design a data format.  This document uses a
   specific design methodology based on the DNS format.

   o  The format is based on JSON objects in order to allow a writer to
      include or exclude parts of the format at will.  No object members
      are ever required.

   o  This format is purposely overly general.  A protocol or
      application that uses this format is expected to use only a subset
      of the items defined here; it is expected to define its own
      profile from this format.

   o  The format allows transformation through JSON that would permit
      re-creation of the wire content of the message.

   o  All members whose values are always 16 bits or shorter are
      represented by JSON numbers with no minus sign, no fractional part
      (except in fields that are specifically noted below), and no
      exponent part.  One-bit values are represented as JSON numbers
      whose values are either 0 or 1.  See Section 6 of [RFC8259] for
      more detail on JSON numbers.

   o  The JSON representation of the objects described in this document
      is limited to the UTF-8 codepoints from U+0000 to U+007F.  This is
      done to prevent an attempt to use a different encoding such as
      UTF-8 for octets in names or data.

Top      ToC       Page 4 
   o  Items that have string values can have "HEX" appended to their
      names to indicate a non-ASCII encoding of the value.  Names that
      end in "HEX" have values stored in base16 encoding (hex with
      uppercase letters) defined in [RFC4648].  This is particularly
      useful for RDATA that is binary.

   o  All field names in this format are used as in [RFC1035], including
      their capitalization.  Names not defined in [RFC1035] generally
      use "camel case".

   o  The same data may be represented in multiple object members
      multiple times.  For example, there is a member for the octets of
      the DNS message header, and there are members for each named part
      of the header.  A message object can thus inadvertently have
      inconsistent data, such as a header member whose value does not
      match the value of the first bits in the entire message member.

   o  It is acceptable that there are multiple ways to represent the
      same data.  This is done so that application designers can choose
      what fields are best for them and even so that they are able to
      allow multiple representations.  That is, there is no "better" way
      to represent DNS data, so this design doesn't prefer specific
      representations.

   o  The design explicitly allows for the description of malformed DNS
      messages.  This is important for systems that are logging messages
      seen on the wire, particularly messages that might be used as part
      of an attack.  A few examples of malformed DNS messages include:

      *  a resource record (RR) that has an RDLENGTH of 4 but an RDATA
         whose length is longer than 4 (if it is the last RR in a
         message)

      *  a DNS message whose QDCOUNT is 0

      *  a DNS message whose ANCOUNT is large but there are insufficient
         bytes after the header

      *  a DNS message whose length is less than 12 octets, meaning it
         doesn't even have a full header

   o  An object in this format can have zero or more of the members
      defined here; that is, no members are required by the format
      itself.  Instead, profiles that use this format might have
      requirements for mandatory members, optional members, and
      prohibited members from the format.  Also, this format does not
      prohibit members that are not defined in this format; profiles of
      the format are free to add new members in the profile.

Top      ToC       Page 5 
   o  This document defines DNS messages, not the zone files described
      in [RFC1035].  A different specification could be written to
      extend it to represent zone files.  Note that DNS zone files allow
      escaping of octet values using "\DDD" notation, but this
      specification does not allow that; when encoding from a zone file
      to this JSON format, you need to do a conversion for many types of
      values.

1.2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  JSON Format for DNS Messages

   The following gives all of the members defined for a DNS message.  It
   is organized approximately by levels of the DNS message.

2.1.  Message Object Members

   o  ID - Integer whose value is 0 to 65535

   o  QR - Boolean

   o  Opcode - Integer whose value is 0 to 15

   o  AA - Boolean

   o  TC - Boolean

   o  RD - Boolean

   o  RA - Boolean

   o  AD - Boolean

   o  CD - Boolean

   o  RCODE - Integer whose value is 0 to 15

   o  QDCOUNT - Integer whose value is 0 to 65535

   o  ANCOUNT - Integer whose value is 0 to 65535

   o  NSCOUNT - Integer whose value is 0 to 65535

Top      ToC       Page 6 
   o  ARCOUNT - Integer whose value is 0 to 65535

   o  QNAME - String of the name of the first Question section of the
      message; see Section 2.6 for a description of the contents

   o  compressedQNAME - Object that describes the name with two optional
      values: "isCompressed" (with a value of 0 for no and 1 for yes)
      and "length" (with an integer giving the length in the message)

   o  QTYPE - Integer whose value is 0 to 65535, of the QTYPE of the
      first Question section of the message

   o  QTYPEname - String whose value is from the IANA "Resource Record
      (RR) TYPEs" registry or has the format in [RFC3597]; this is case
      sensitive, so "AAAA", not "aaaa"

   o  QCLASS - Integer whose value is 0 to 65535, of the QCLASS of the
      first Question section of the message

   o  QCLASSname - String whose value is "IN", "CH", or "HS" or that has
      the format in [RFC3597]

   o  questionRRs - Array of zero or more resource records or rrSet
      objects in the Question section

   o  answerRRs - Array of zero or more resource records or rrSet
      objects in the Answer section

   o  authorityRRs - Array of zero or more resource records or rrSet
      objects in the Authority section

   o  additionalRRs - Array of zero or more resource records or rrSet
      objects in the Additional section

2.2.  Resource Record Object Members

   A resource record is represented as an object with the following
   members.

   o  NAME - String of the NAME field of the resource record; see
      Section 2.6 for a description of the contents

   o  compressedNAME - Object that describes the name with two optional
      values: "isCompressed" (with a value of 0 for no and 1 for yes)
      and "length" (with an integer giving the length in the message)

   o  TYPE - Integer whose value is 0 to 65535

Top      ToC       Page 7 
   o  TYPEname - String whose value is from the IANA "Resource Record
      (RR) TYPEs" registry or has the format in [RFC3597]; this is case
      sensitive, so "AAAA", not "aaaa"

   o  CLASS - Integer whose value is 0 to 65535

   o  CLASSname - String whose value is "IN", "CH", or "HS" or has the
      format in [RFC3597]

   o  TTL - Integer whose value is -2147483648 to 2147483647 (it will
      only be 0 to 2147483647 in normal circumstances)

   o  RDLENGTH - Integer whose value is 0 to 65535.  Applications using
      this format are unlikely to use this value directly, and instead
      calculate the value from the RDATA.

   o  RDATAHEX - Hex-encoded string (base16 encoding, described in
      [RFC4648]) of the octets of the RDATA field of the resource
      record.  The data in some common RDATA fields are also described
      in their own members; see Section 2.3

   o  rrSet - List of objects that have RDLENGTH and RDATA members

   A Question section can be expressed as a resource record.  When doing
   so, the TTL, RDLENGTH, and RDATA members make no sense.

2.3.  Specific RDATA Field Members

   The following are common RDATA types and how to specify them as JSON
   members.  The name of the member contains the name of the RDATA type.
   The data type for each of these members is a string.  Each name is
   prefaced with "rdata" to prevent a name collision with fields that
   might later be defined that have the same name as the raw type name.

   o  rdataA - IPv4 address, such as "192.168.33.44"

   o  rdataAAAA - IPv6 address, such as "fe80::a65e:60ff:fed6:8aaf", as
      defined in [RFC5952]

   o  rdataCNAME - A domain name

   o  rdataDNAME - A domain name

   o  rdataNS - A domain name

   o  rdataPTR - A domain name

   o  rdataTXT - A text value

Top      ToC       Page 8 
   In addition, each of the following members has a value that is a
   space-separated string that matches the display format definition in
   the RFC that defines that RDATA type.  It is not expected that every
   receiving application will know how to parse these values.

   rdataCDNSKEY, rdataCDS, rdataCSYNC, rdataDNSKEY, rdataHIP,
   rdataIPSECKEY, rdataKEY, rdataMX, rdataNSEC, rdataNSEC3,
   rdataNSEC3PARAM, rdataOPENPGPKEY, rdataRRSIG, rdataSMIMEA, rdataSPF,
   rdataSRV, rdataSSHFP, rdataTLSA

2.4.  The Message and Its Parts as Octets

   The following can be members of a message object.  These members are
   all encoded in base16 encoding, described in [RFC4648].  All these
   items are strings.

   o  messageOctetsHEX - The octets of the message

   o  headerOctetsHEX - The first 12 octets of the message (or fewer, if
      the message is truncated)

   o  questionOctetsHEX - The octets of the Question section

   o  answerOctetsHEX - The octets of the Answer section

   o  authorityOctetsHEX - The octets of the Authority section

   o  additionalOctetsHEX - The octets of the Additional section

   The following can be a member of a resource record object.

   o  rrOctetsHEX - The octets of a particular resource record

   The items in this section are useful in applications to canonically
   reproduce what appeared on the wire.  For example, an application
   that is converting wire-format requests and responses might do
   decompression of names, but the system reading the converted data may
   want to be sure the decompression was done correctly.  Such a system
   would need to see the part of the message where the decompressed
   labels resided, such as in one of the items in this section.

2.5.  Additional Message Object Members

   The following are members that might appear in a message object:

   o  dateString - The date that the message was sent or received, given
      as a string in the standard format described in [RFC3339] and
      refined by Section 3.3 of [RFC4287].

Top      ToC       Page 9 
   o  dateSeconds - The date that the message was sent or received,
      given as a JSON number that is the number of seconds since
      1970-01-01T00:00Z in UTC time; this number can be fractional.
      This number must have no minus sign, can have an optional
      fractional part, and can have no exponent part.

   o  comment - An unstructured comment as a string.

2.6.  Name Fields

   Names are represented by JSON strings.  The rules for how names are
   encoded are described in Section 1.1.  (To recap: it is limited to
   the UTF-8 codepoints from U+0000 to U+007F.)  The contents of these
   fields are always uncompressed; that is, after [RFC1035], name
   compression has been removed.

   There are two encodings for names:

   o  If the member name does not end in "HEX", the value is a domain
      name encoded as DNS labels consisting of UTF-8 codepoints from
      U+0000 to U+007F.  Within a label, codepoints above U+007F and the
      codepoint U+002E (ASCII period) MUST be expressed using JSON's
      escaping rules within this set of codepoints.  Separation between
      labels is indicated with a period (codepoint U+002E).
      Internationalized Domain Name (IDN) labels are always expressed in
      their A-label form, as described in [RFC5890].

   o  If the member name ends in "HEX", the value is the wire format for
      an entire domain name stored in base16 encoding, which is
      described in [RFC4648].

3.  JSON Format for a Paired DNS Query and Response

   A paired DNS query and response is represented as an object.  Two
   optional members of this object are named "queryMessage" and
   "responseMessage", and each has a value that is a message object.
   This design was chosen (as compared to the more obvious array of two
   values) so that a paired DNS query and response could be
   differentiated from a stream of DNS messages whose length happens to
   be two.

4.  Streaming DNS Objects

   Streaming of DNS objects is performed using JSON text sequences
   [RFC7464].

Top      ToC       Page 10 
5.  Examples

5.1.  Example of the Format of a DNS Query

   The following is an example of a query for the A record of
   example.com.

   { "ID": 19678, "QR": 0, "Opcode": 0,
     "AA": 0, "TC": 0, "RD": 0, "RA": 0, "AD": 0, "CD": 0, "RCODE": 0,
     "QDCOUNT": 1, "ANCOUNT": 0, "NSCOUNT": 0, "ARCOUNT": 0,
     "QNAME": "example.com", "QTYPE": 1, "QCLASS": 1
   }

   As stated earlier, all members of an object are optional.  This
   example object could have one or more of the following members as
   well:

   "answerRRs": []
   "authorityOctetsHEX": ""
   "comment": "Something pithy goes here"
   "dateSeconds": 1408504748.657783
   "headerOctetsHEX": "4CDE00000001000000000000"
   "QNAMEHEX": "076578616D706C6503636F6D00",
   "compressedQNAME": { "isCompressed": 0 },
   "messageOctetsHEX":
        "4CDE00000001000000000000076578616D706C6503636F6D0000010001"
   "questionOctetsHEX": "076578616D706C6503636F6D0000010001"
   "questionRRs": [ { "NAMEHEX": "076578616D706C6503636F6D00",
                  "TYPE": 1, "CLASS": 1, "hostNAME" : "example.com." } ]
   "questionRRs": [ { "NAME": "example.com.", "TYPE": 1,
                  "CLASS": 1, } ]

   (Note that this is an incomplete list of what else could be in the
   object.)

Top      ToC       Page 11 
5.2.  Example of the Format of a Paired DNS Query and Response

   The following is a paired DNS query and response for a query for the
   A record of example.com.

   {
     "queryMessage": { "ID": 32784, "QR": 0, "Opcode": 0, "AA": 0,
                      "TC": 0, "RD": 0, "RA": 0, "AD": 0, "CD": 0,
                      "RCODE": 0, "QDCOUNT": 1, "ANCOUNT": 0,
                      "NSCOUNT": 0, "ARCOUNT": 0,
                      "QNAME": "example.com.",
                      "QTYPE": 1, "QCLASS": 1 },
     "responseMessage": { "ID": 32784, "QR": 1, "AA": 1, "RCODE": 0,
                         "QDCOUNT": 1, "ANCOUNT": 1, "NSCOUNT": 1,
                         "ARCOUNT": 0,
                         "answerRRs": [ { "NAME": "example.com.",
                                          "TYPE": 1, "CLASS": 1,
                                          "TTL": 3600,
                                          "RDATAHEX": "C0000201" },
                                        { "NAME": "example.com.",
                                          "TYPE": 1, "CLASS": 1,
                                          "TTL": 3600,
                                          "RDATAHEX": "C000AA01" } ],
                          "authorityRRs": [ { "NAME": "ns.example.com.",
                                              "TYPE": 1, "CLASS": 1,
                                              "TTL": 28800,
                                              "RDATAHEX": "CB007181" } ]
                       }
   }

   The Answer section could instead be given with an rrSet:

   "answerRRs": [ { "NAME": "example.com.",
                    "TYPE": 1, "CLASS": 1,
                    "TTL": 3600,
                    "rrSet": [ { "RDATAHEX": "C0000201" },
                               { "RDATAHEX": "C000AA01" } ] } ],

   (Note that this is an incomplete list of what else could be in the
   Answer section.)

Top      ToC       Page 12 
6.  Local Format Policy

   Systems using the format in this document will likely have policy
   about what must be in the objects.  Those policies are outside the
   scope of this document.

   For example, passive DNS systems such as those described in
   [PASSIVE-DNS] cover just DNS responses.  Such a system might have a
   policy that makes QNAME, QTYPE, and answerRRs mandatory.  That
   document also describes two mandatory times that are not in this
   format, so the policy would possibly also define those members and
   make them mandatory.  The policy could also define additional members
   that might appear in a record.

   As another example, a program that uses this format for configuring
   what a test client sends on the wire might have a policy of "each
   record object can have as few members as it wants; all unstated
   members are filled in from previous records".

7.  IANA Considerations

7.1.  Media Type Registration of application/dns+json

   Type name: application

   Subtype name: dns+json

   Required parameters: N/A

   Optional parameters: N/A

   Encoding considerations:  Encoding considerations are identical to
   those specified for the "application/json" media type.

   Security considerations:  This document specifies the security
   considerations for the format.

   Interoperability considerations:  This document specifies format of
   conforming messages and the interpretation thereof.

   Published specification:  This document

   Applications that use this media type:  Systems that want to exchange
   DNS messages

   Fragment identifier considerations:  None

Top      ToC       Page 13 
   Additional information:

     Deprecated alias names for this type: N/A

     Magic number(s):  N/A

     File extension(s):  This document uses the media type to refer to
     protocol messages and thus does not require a file extension.

     Macintosh file type code(s):  N/A

   Person & email address to contact for further information:
   Paul Hoffman, paul.hoffman@icann.org

   Intended usage:  COMMON

   Restrictions on usage:  N/A

   Author:  Paul Hoffman, paul.hoffman@icann.org

   Change controller:  Paul Hoffman, paul.hoffman@icann.org

8.  Security Considerations

   As described in Section 1.1, a message object can have inconsistent
   data, such as a message with an ANCOUNT of 1 but that has either an
   empty answerRRs array or an answerRRs array that has two or more RRs.
   Other examples of inconsistent data would be resource records whose
   RDLENGTH does not match the length of the decoded value in the
   RDATAHEX member, a record whose various header fields do not match
   the value in headerOctetsHEX, and so on.  A reader of this format
   must never assume that all of the data in an object are all
   consistent with each other.

   This document describes a format, not a profile of that format.  Lack
   of profile can lead to security issues.  For example, if a system has
   a filter for JSON representations of DNS packets, that filter needs
   to have the same semantics for the output JSON as the consumer has.
   Unless the profile is quite tight, this can lead to the producer
   being able to create fields with different contents (using the HEX
   and regular formats), fields with malformed lengths, and so on.

   Numbers in JSON do not have any bounds checking.  Thus, integer
   values in a record might have invalid values, such as an ID field
   whose value is greater than or equal to 2^16, a QR field that has a
   value of 2, and so on.

Top      ToC       Page 14 
9.  Privacy Considerations

   The values that can be contained in this format may contain privacy-
   sensitive information.  For example, a profile of this format that is
   used for logging queries sent to recursive resolvers might have
   source IP addresses that could identify the location of the person
   who sent the DNS query.

10.  References

10.1.  Normative References

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <https://www.rfc-editor.org/info/rfc1035>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <https://www.rfc-editor.org/info/rfc3339>.

   [RFC3597]  Gustafsson, A., "Handling of Unknown DNS Resource Record
              (RR) Types", RFC 3597, DOI 10.17487/RFC3597, September
              2003, <https://www.rfc-editor.org/info/rfc3597>.

   [RFC4287]  Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
              Syndication Format", RFC 4287, DOI 10.17487/RFC4287,
              December 2005, <https://www.rfc-editor.org/info/rfc4287>.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <https://www.rfc-editor.org/info/rfc4648>.

   [RFC5890]  Klensin, J., "Internationalized Domain Names for
              Applications (IDNA): Definitions and Document Framework",
              RFC 5890, DOI 10.17487/RFC5890, August 2010,
              <https://www.rfc-editor.org/info/rfc5890>.

   [RFC5952]  Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
              Address Text Representation", RFC 5952,
              DOI 10.17487/RFC5952, August 2010,
              <https://www.rfc-editor.org/info/rfc5952>.

Top      ToC       Page 15 
   [RFC7464]  Williams, N., "JavaScript Object Notation (JSON) Text
              Sequences", RFC 7464, DOI 10.17487/RFC7464, February 2015,
              <https://www.rfc-editor.org/info/rfc7464>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,
              <https://www.rfc-editor.org/info/rfc8259>.

10.2.  Informative References

   [DNS-QUERY]
              Parthasarathy, M. and P. Vixie, "Representing DNS messages
              using XML", Work in Progress,
              draft-mohan-dns-query-xml-00, September 2011.

   [DNSXML]   Daley, J., Morris, S., and J. Dickinson, "dnsxml - A
              standard XML representation of DNS data", Work in
              Progress, draft-daley-dnsxml-00, July 2013.

   [PASSIVE-DNS]
              Dulaunoy, A., Kaplan, A., Vixie, P., and H. Stern,
              "Passive DNS - Common Output Format", Work in Progress,
              draft-dulaunoy-dnsop-passive-dns-cof-04, June 2018.

Acknowledgements

   Some of the ideas in this document were inspired by earlier,
   abandoned work such as [DNSXML], [DNS-QUERY], and [PASSIVE-DNS].  The
   document was also inspired by early ideas from Stephane Bortzmeyer.
   Many people in the Domain Name System Operations (DNSOP) and DNS Over
   HTTPS (DOH) working groups contributed very useful ideas (even though
   this was not a WG work item).

Author's Address

   Paul Hoffman
   ICANN

   Email: paul.hoffman@icann.org