DNSSEC/NSEC/exampleについて、ここに記述してください。

http://tools.ietf.org/html/rfc4034

4.3. NSEC RR Example

   The following NSEC RR identifies the RRsets associated with
   alfa.example.com. and identifies the next authoritative name after
   alfa.example.com.

   alfa.example.com. 86400 IN NSEC host.example.com. (
                                   A MX RRSIG NSEC TYPE1234 )

• The first four text fields specify the name, TTL, Class, and RR type (NSEC). The entry host.example.com. is the next authoritative name after alfa.example.com. in canonical order. The A, MX, RRSIG, NSEC, and TYPE1234 mnemonics indicate that there are A, MX, RRSIG, NSEC, and TYPE1234 RRsets associated with the name alfa.example.com.

(...)

• Assuming that the validator can authenticate this NSEC record, it could be used to prove that beta.example.com does not exist, or to prove that there is no AAAA record associated with alfa.example.com. Authenticated denial of existence is discussed in [RFC4035].