= DNS/ワイルドカード =

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[[DNS/用語/wildcards]] 

wildcardレコードとして定義されているかの、確認法：

間違いの多い機能である。

== awsdns ==
awsでの制限:  [[/awsdns]]

https://docs.aws.amazon.com/ja_jp/Route53/latest/DeveloperGuide/DomainNameFormat.html#domain-name-format-asterisk

*.example.com という名前のレコードを作成し、example.com レコードがない場合、
Route 53 は NXDOMAIN (存在しないドメイン) として example.com の DNS クエリに応答します。 

NS タイプのあるレコードで「*」をワイルドカードとして使用することはできません。
  You can't use the * as a wildcard for records that have a type of NS.

== RFC 4592 ==
この使い方は禁止されてはいないが、使わない方がよい。

{{{
4.1.  SOA RRSet at a Wildcard Domain Name

      $ORIGIN *.example.
      @                 3600 IN  SOA   <SOA RDATA>
                        3600     NS    ns1.example.com.
                        3600     NS    ns1.example.net.
      www               3600     TXT   "the www txt record"

A query for www.*.example.'s TXT record would still find the "the www
   txt record" answer.  The asterisk label only becomes significant when
   section 4.3.2, step 3, part 'c' is in effect.

}}}

{{{

4.2.  NS RRSet at a Wildcard Domain Name

   With the definition of DNSSEC [RFC4033, RFC4034, RFC4035] now in
   place, the semantics of a wildcard domain name owning an NS RRSet has
   come to be poorly defined.  The dilemma relates to a conflict between
   the rules for synthesis in part 'c' and the fact that the resulting
   synthesis generates a record for which the zone is not authoritative.
   In a DNSSEC signed zone, the mechanics of signature management
   (generation and inclusion in a message) have become unclear.

   Salient points of the working group discussion on this topic are
   summarized in section 4.2.1.
}}}

{{{
   As a result of these discussions, there is no definition given for
   wildcard domain names owning an NS RRSet.  The semantics are left
   undefined until there is a clear need to have a set defined, and
   until there is a clear direction to proceed.  

Operationally, inclusion of wildcard NS RRSets in a zone is discouraged,
but not barred.
}}}