I did not see any differences when asking for the specific nameserver about some hostame. However, I was able to fix this problem. Having the debug and recurse options on did not point me in the right direction b/c I did not see the method ptrdname in the debug output.

FIX WAS: I needed to change address method to ptrdname method. I found this using dumper on the $rr variable. Thank you for your persistence and help! :)

my $res = Net::DNS::Resolver->new(
    nameservers => [qw(ns7.xx.com xx.xx.xx.com)],
    recurse     => 0, ## dont do recursive lookups
    debug       => 0,
);

my $query = $res->search("10.xx.xx.55");
use Data::Dumper;
#print Dumper($query);
#exit;
  if ($query) {
      foreach my $rr ($query->answer) {
          next unless $rr->type eq "PTR"; ## skip record if not eq PTR
+ ##
          print $rr->ptrdname, "\n";
          print Dumper($rr);
      }
  }
  else {
      warn "query failed: ", $res->errorstring, "\n";
  }

#for my $key (keys %ns7IP) {
#    print $key,' => ',join "\n\t", sort @{$ns7IP{$key}},"\n";
#}
print "\n";
"DNS_results.plx" 71 lines, 2813 characters
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root@xxxxx(R3 Prod):/home/
# perl  DNS_results.plx
sap005.alxxxmeX.com
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$VAR1 = bless( {
                 'rdlength' => 22,
                 'ttl' => 2195,
                 'name' => '55.xx.xx.10.in-addr.arpa',
                 'ptrdname' => 'sap005.alxxxsmeX.com',
                 'class' => 'IN',
                 'type' => 'PTR',
                 'rdata' => 'sap005     alarixxxxx'
               }, 'Net::DNS::RR::PTR' );
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