DNS/用語/wildcards/RFC4592/exampleについて、ここに記述してください。

2.2.1. An Example 

   To illustrate what is meant by existence consider this complete zone:

      $ORIGIN example.
      example.                 3600 IN  SOA   <SOA RDATA>
      example.                 3600     NS    ns.example.com.
      example.                 3600     NS    ns.example.net.
      *.example.               3600     TXT   "this is a wildcard"
      *.example.               3600     MX    10 host1.example.
      sub.*.example.           3600     TXT   "this is not a wildcard"
      host1.example.           3600     A     192.0.2.1
      _ssh._tcp.host1.example. 3600     SRV   <SRV RDATA>
      _ssh._tcp.host2.example. 3600     SRV   <SRV RDATA>
      subdel.example.          3600     NS    ns.example.com.
      subdel.example.          3600     NS    ns.example.net.

   # Wildcard RRs do not apply:
   #
   ...
   #   - When the query name or a name between the wildcard domain and
   #     the query name is know[n] to exist. . . .

The following responses would not be synthesized from any of the wildcards in the zone: 

QNAME=_telnet._tcp.host1.example., QTYPE=SRV, QCLASS=IN
    because _tcp.host1.example. exists (without data)

wildcard domain は *.example (あるいはexampleの下）ということのようだ。