Reverse lookup of selected IP addresses without delegation agreement?

[Ralph]

Len Conrad wrote:

 > so set up the specific IPs in your DNS as zones with one PTR record.
 > spoofing complete.

So if I stick to my own example of mail.sourceforge.net, I'd use these
settings?

   # named.conf
   zone "206.250.35.66.in-addr.arpa" in {
     type master;
     file "206.250.35.66.zone";
   };

   # 206.250.35.66.zone
   @  IN SOA  ns.mydomain.tld. hostmaster.mydomain.tld. ( ... )
      IN NS   ns.mydomain.tld.
   206.250.35.66.in-addr.arpa.  IN PTR  mail.sourceforge.net.

I want to make sure that I "intercept" only reverse lookups for the
selected hosts I choose to define, but let all other lookups pass
unmodified.

BTW, this would require a .zone file for each host, right? Or is it
possible to use one "hijacked.zone" with multiple entries if I make
use of $ORIGIN statements?

 > With RFC 2317, the child zone's PTR records must match the CNAME
 > rdata fields in the parent zone.

Can this cause any trouble for my users if I use the configuration
shown above?

Ralph