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---
- name: dns
  title: DNS
  group: 2
  short: Fields describing DNS queries and answers.
  description: >
    Fields describing DNS queries and answers.

    DNS events should either represent a single DNS query prior to getting answers
    (`dns.type:query`) or they should represent a full exchange and contain
    the query details as well as all of the answers that were provided for this
    query (`dns.type:answer`).
  type: group
  fields:

    - name: type
      level: extended
      type: keyword
      short: The type of DNS event captured, query or answer.
      description: >
        The type of DNS event captured, query or answer.

        If your source of DNS events only gives you DNS queries, you should only
        create dns events of type `dns.type:query`.

        If your source of DNS events gives you answers as well, you should create
        one event per query (optionally as soon as the query is seen). And a
        second event containing all query details as well as an array of answers.
      example: answer

    - name: id
      level: extended
      type: keyword
      description: >
        The DNS packet identifier assigned by the program that generated the
        query. The identifier is copied to the response.
      example: 62111

    - name: op_code
      level: extended
      type: keyword
      short: The DNS operation code that specifies the kind of query in the message.
      description: >
        The DNS operation code that specifies the kind of query in the message.
        This value is set by the originator of a query and copied into the
        response.
      example: QUERY

    - name: header_flags
      level: extended
      type: keyword
      short: Array of DNS header flags.
      description: >
        Array of 2 letter DNS header flags.
      expected_values:
        - AA
        - TC
        - RD
        - RA
        - AD
        - CD
        - DO
      example: "[\"RD\", \"RA\"]"
      normalize:
        - array

    - name: response_code
      level: extended
      type: keyword
      description: The DNS response code.
      example: NOERROR

    - name: question.name
      level: extended
      type: keyword
      short: The name being queried.
      description: >
        The name being queried.

        If the name field contains non-printable
        characters (below 32 or above 126), those characters should be represented
        as escaped base 10 integers (\DDD). Back slashes and quotes should be escaped.
        Tabs, carriage returns, and line feeds should be converted to \t, \r, and
        \n respectively.
      example: www.example.com

    - name: question.type
      level: extended
      type: keyword
      description: The type of record being queried.
      example: AAAA

    - name: question.class
      level: extended
      type: keyword
      description: The class of records being queried.
      example: IN

    - name: question.registered_domain
      level: extended
      type: keyword
      short: The highest registered domain, stripped of the subdomain.
      description: >
        The highest registered domain, stripped of the subdomain.

        For example, the registered domain for "foo.example.com" is "example.com".

        This value can be determined precisely with a list like the public
        suffix list (http://publicsuffix.org). Trying to approximate this by
        simply taking the last two labels will not work well for TLDs such as "co.uk".
      example: example.com

    - name: question.top_level_domain
      level: extended
      type: keyword
      short: The effective top level domain (com, org, net, co.uk).
      description: >
        The effective top level domain (eTLD), also known as the domain suffix,
        is the last part of the domain name.
        For example, the top level domain for example.com is "com".

        This value can be determined precisely with a list like the public
        suffix list (http://publicsuffix.org). Trying to approximate this by
        simply taking the last label will not work well for effective TLDs such as "co.uk".
      example: co.uk

    - name: question.subdomain
      level: extended
      type: keyword
      short: The subdomain of the domain.
      description: >
        The subdomain is all of the labels under the registered_domain.

        If the domain has multiple levels of subdomain, such as "sub2.sub1.example.com",
        the subdomain field should contain "sub2.sub1", with no trailing period.
      example: www

    - name: answers
      level: extended
      type: object
      short: Array of DNS answers.
      description: >
        An array containing an object for each answer section returned by
        the server.

        The main keys that should be present in these objects are defined by ECS.
        Records that have more information may contain more keys than what
        ECS defines.

        Not all DNS data sources give all details about DNS answers.
        At minimum, answer objects must contain the `data` key.
        If more information is available, map as much of it to ECS as possible,
        and add any additional fields to the answer objects as custom fields.
      normalize:
        - array

    - name: answers.name
      level: extended
      type: keyword
      short: The domain name to which this resource record pertains.
      description: >
        The domain name to which this resource record pertains.

        If a chain of CNAME is being resolved, each answer's `name` should be
        the one that corresponds with the answer's `data`. It should not simply
        be the original `question.name` repeated.
      example: www.example.com

    - name: answers.type
      level: extended
      type: keyword
      description: The type of data contained in this resource record.
      example: CNAME

    - name: answers.class
      level: extended
      type: keyword
      description: The class of DNS data contained in this resource record.
      example: IN

    - name: answers.ttl
      level: extended
      type: long
      short: The time interval in seconds that this resource record may be cached
        before it should be discarded.
      description: >
        The time interval in seconds that this resource record may be cached
        before it should be discarded. Zero values mean that the data should
        not be cached.
      example: 180

    - name: answers.data
      level: extended
      type: keyword
      short: The data describing the resource.
      description: >
        The data describing the resource.

        The meaning of this data depends on the type and class of the resource
        record.
      example: 10.10.10.10

    - name: resolved_ip
      level: extended
      type: ip
      short: Array containing all IPs seen in answers.data
      description: >
        Array containing all IPs seen in `answers.data`.

        The `answers` array can be difficult to use, because of the variety of
        data formats it can contain. Extracting all IP addresses seen in there to
        `dns.resolved_ip` makes it possible to index them as IP addresses, and
        makes them easier to visualize and query for.
      example: '["10.10.10.10", "10.10.10.11"]'
      normalize:
        - array
