Question about RFC-2317

[Clenna Lumina]

I was reading about RFC-2317
(http://www.ietf.org/rfc/rfc2317.txt, found via google... is
there a newer one?) 

While I feel I have grasped a lot about DNS/Bind the past
couple months (enough to setup zones for my LAN and started
to manage a couple external domains I've since had deligated
to me), I can't see understand one part in this RFC document.

On page 2 (and 3) it shwos a nice example of how to partition
a class C address space into chunks (in that case, starting
from 192.0.2.0, /25, /26, and /26

I understand that CNAMing in the parent zone is needed,
acccording to this RFC.

What I can't seem to figure out for the life of me is *why*
this is needed?

(Example parent zone from RFC-2317)
---------------------------------------
   $ORIGIN 2.0.192.in-addr.arpa.
   @       IN      SOA     my-ns.my.domain.
hostmaster.my.domain. (...)
   ;...
   ;  <<0-127>> /25
   0/25            NS      ns.A.domain.
   0/25            NS      some.other.name.server.
   ;
   1               CNAME   1.0/25.2.0.192.in-addr.arpa.
   2               CNAME   2.0/25.2.0.192.in-addr.arpa.
   3               CNAME   3.0/25.2.0.192.in-addr.arpa.
   ;
   ;  <<128-191>> /26
   128/26          NS      ns.B.domain.
   128/26          NS      some.other.name.server.too.
   ;
   129             CNAME   129.128/26.2.0.192.in-addr.arpa.
   130             CNAME   130.128/26.2.0.192.in-addr.arpa.
   131             CNAME   131.128/26.2.0.192.in-addr.arpa.
   ;
   ;  <<192-255>> /26
   192/26          NS      ns.C.domain.
   192/26          NS      some.other.third.name.server.
   ;
   193             CNAME   193.192/26.2.0.192.in-addr.arpa.
   194             CNAME   194.192/26.2.0.192.in-addr.arpa.
   195             CNAME   195.192/26.2.0.192.in-addr.arpa.
---------------------------------------

It doesn't seem to make sense with the NS entries pointing to
the name servers that those chunks (/lengths) are being
deligated to. Wouldn't each respective NS server(s) handle it
instead. The CNAME is just an alias, right, so is it needed
here? As a fall back messure? Unless I've missed something,
the RFC doesn't seem to expalin that.

Thanks.

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