Try this:

my $name = nslookup(host => "206.33.105.41", type => "PTR");

Uses 'host' for a key in the PTR query instead of 'domain'. I just copied the example provided in the module's documentation.

http://search.cpan.org/~darren/Net-Nslookup-1.18/lib/Net/Nslookup.pm

Update: It doesn't work for me either. This module is just a wrapper for Net::DNS. You can fix the problem by deleting an if statement in its _lookup_ptr function.

If you substitute the following ...

    $query = $res->search($term, "PTR") || return;
    for $rr ($query->answer) {
        if ($rr->can('ptrdname')) {
            push @answers, $rr->ptrdname;
        }
    }
[download]

with ...

    $query = $res->search($term, "PTR") || return;
    for $rr ($query->answer) {
            push @answers, $rr->ptrdname;
    }
[download]

then it works as expected :)