draft-ietf-dnsext-dns-name-p-s-00.txt

非常好的dns解析软件

       This approach would make it possible to enumerate all DNS names
       in the zone containing a first-level label beginning with
       underscore, including all SRV RRs, but this may be of less a
       concern to the zone administrator than incurring the overhead of
       the absolute method or of the following variants of the modified
       method.

   2.  The absolute method could be used for synthesising NSEC RRs for
       all queries where the QNAME contains a leading underscore.
       However this re-introduces the susceptibility of the absolute
       method to denial of service activity, as an attacker could send
       queries for an effectively inexhaustible supply of domain names
       beginning with a leading underscore.

   3.  A variant of the modified method could be used for synthesising
       NSEC RRs for all queries where the QNAME contains a leading
       underscore.  This variant would assume that all predecessors and
       successors to queries where the QNAME contains a leading
       underscore may consist of two lablels rather than only one.  This
       introduces a little additional complexity without incurring the
       full increase in response size and computational complexity as
       the absolute method.

   4.  Finally, a variant the modified method which assumes that all
       owner names in the zone consist of one or two labels could be
       used.  However this negates much of the reduction in response
       size of the modified method and may be nearly as computationally
       complex as the absolute method.





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6.  Examples

   In the following examples:

      the owner name of the zone apex is "example.com.";

      the range of octet values is 0x00 - 0xff excluding values
      corresponding to uppercase US-ASCII letters; and

      non-printable octet values are expressed as three-digit decimal
      numbers preceded by a backslash (as specified in Section 5.1 of
      [RFC1035]).

6.1.  Examples of Immediate Predecessors Using Absolute Method

   Example of typical case:

      P(foo.example.com.) =

           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255.\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255.\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255.fon\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255.example.com.

      or, in alternate notation:

           \255{49}.\255{63}.\255{63}.fon\255{60}.example.com.

      where {n} represents the number of repetitions of an octet.






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   Example where least significant (left-most) label of DNS name
   consists of a single octet of the minimum sort value:

      P(\000.foo.example.com.) = foo.example.com.

   Example where least significant (right-most) octet of least
   significant (left-most) label has the minimum sort value:

      P(foo\000.example.com.) =

           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255.\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255.\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255.\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255.foo.example.com.

      or, in alternate notation:

           \255{45}.\255{63}.\255{63}.\255{63}.foo.example.com.

















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   Example where DNS name contains an octet which must be decremented by
   skipping values corresponding to US-ASCII uppercase letters:

      P(fo\[.example.com.) =

           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255.\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255.\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255.fo\@\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255.example.com.

      or, in alternate notation:

           \255{49}.\255{63}.\255{63}.fo\@\255{60}.example.com.

      where {n} represents the number of repetitions of an octet.




















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   Example where DNS name is the owner name of the zone apex, and
   consequently wraps to the DNS name with the maximum possible sort
   order in the zone:

      P(example.com.) =

           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255.\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255.\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255.\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255.example.com.

      or, in alternate notation:

           \255{49}.\255{63}.\255{63}.\255{63}.example.com.

6.2.  Examples of Immediate Successors Using Absolute Method

   Example of typical case:

      S(foo.example.com.) = \000.foo.example.com.














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   Example where DNS name is one octet short of the maximum DNS name
   length:

      N =  fooooooooooooooooooooooooooooooooooooooooooooooo
           .ooooooooooooooooooooooooooooooooooooooooooooooo
           oooooooooooooooo.ooooooooooooooooooooooooooooooo
           oooooooooooooooooooooooooooooooo.ooooooooooooooo
           oooooooooooooooooooooooooooooooooooooooooooooooo.example.com.

      or, in alternate notation:

           fo{47}.o{63}.o{63}.o{63}.example.com.

      S(N) =

           fooooooooooooooooooooooooooooooooooooooooooooooo
           \000.ooooooooooooooooooooooooooooooooooooooooooo
           oooooooooooooooooooo.ooooooooooooooooooooooooooo
           oooooooooooooooooooooooooooooooooooo.ooooooooooo
           oooooooooooooooooooooooooooooooooooooooooooooooo
           oooo.example.com.

      or, in alternate notation:

           fo{47}\000.o{63}.o{63}.o{63}.example.com.


























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   Example where DNS name is the maximum DNS name length:

      N  = fooooooooooooooooooooooooooooooooooooooooooooooo
           o.oooooooooooooooooooooooooooooooooooooooooooooo
           ooooooooooooooooo.oooooooooooooooooooooooooooooo
           ooooooooooooooooooooooooooooooooo.oooooooooooooo
           oooooooooooooooooooooooooooooooooooooooooooooooo
           o.example.com.

      or, in alternate notation:

           fo{48}.o{63}.o{63}.o{63}.example.com.

      S(N) =

           fooooooooooooooooooooooooooooooooooooooooooooooo
           p.oooooooooooooooooooooooooooooooooooooooooooooo
           ooooooooooooooooo.oooooooooooooooooooooooooooooo
           ooooooooooooooooooooooooooooooooo.oooooooooooooo
           oooooooooooooooooooooooooooooooooooooooooooooooo
           o.example.com.

      or, in alternate notation:

           fo{47}p.o{63}.o{63}.o{63}.example.com.


























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   Example where DNS name is the maximum DNS name length and the least
   significant (left-most) label has the maximum sort value:

      N =  \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255\255\255\255\255\255\255\255\255\255\255\255
           \255.ooooooooooooooooooooooooooooooooooooooooooo
           oooooooooooooooooooo.ooooooooooooooooooooooooooo
           oooooooooooooooooooooooooooooooooooo.ooooooooooo
           oooooooooooooooooooooooooooooooooooooooooooooooo
           oooo.example.com.

      or, in alternate notation:

           \255{49}.o{63}.o{63}.o{63}.example.com.

      S(N) =

           oooooooooooooooooooooooooooooooooooooooooooooooo
           oooooooooooooop.oooooooooooooooooooooooooooooooo
           ooooooooooooooooooooooooooooooo.oooooooooooooooo
           ooooooooooooooooooooooooooooooooooooooooooooooo.
           example.com.

      or, in alternate notation:

           o{62}p.o{63}.o{63}.example.com.























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   Example where DNS name is the maximum DNS name length and the eight
   least significant (right-most) octets of the least significant (left-
   most) label have the maximum sort value:

      N  = foooooooooooooooooooooooooooooooooooooooo\255
           \255\255\255\255\255\255\255.ooooooooooooooooooo
           oooooooooooooooooooooooooooooooooooooooooooo.ooo
           oooooooooooooooooooooooooooooooooooooooooooooooo
           oooooooooooo.ooooooooooooooooooooooooooooooooooo
           oooooooooooooooooooooooooooo.example.com.

      or, in alternate notation:

           fo{40}\255{8}.o{63}.o{63}.o{63}.example.com.

      S(N) =

           fooooooooooooooooooooooooooooooooooooooop.oooooo
           oooooooooooooooooooooooooooooooooooooooooooooooo
           ooooooooo.oooooooooooooooooooooooooooooooooooooo
           ooooooooooooooooooooooooo.oooooooooooooooooooooo
           ooooooooooooooooooooooooooooooooooooooooo.example.com.

      or, in alternate notation:

           fo{39}p.o{63}.o{63}.o{63}.example.com.