well, when I run it, the two $rr tokens that come back from the $query->answer call are both of type CNAME, not NS. So nothing comes out of the script except the header, since you never hit another print statement.

  DB<1> c 21
  DB<2> x $query->answer()
0  Net::DNS::RR::CNAME=HASH(0x8755fc8)
   'class' => 'IN'
   'cname' => 'rc.yahoo.com'
   'name' => 'http://www.yahoo.com'
   'rdata' => "\cBrcÀ\cW"
   'rdlength' => 5
   'ttl' => 1759
   'type' => 'CNAME'
1  Net::DNS::RR::CNAME=HASH(0x8755f98)
   'class' => 'IN'
   'cname' => 'rc.yahoo.akadns.net'
   'name' => 'rc.yahoo.com'
   'rdata' => "\cBrc\cEyahoo\cFakadns\cCnet\c@"
   'rdlength' => 21
   'ttl' => 1759
   'type' => 'CNAME'
[download]

But I'm just running it from the commandline; haven't tested it in CGI environment proper.

Update: hv is right, the shebang line is funky too. I was running it with explicit call to perl cgi-test.pl from within emacs, so I didn't notice.