Can't call method "search" on an undefined value at ./test.pl line 8.

##</code><code>##

use NetAddr::IP;
use Net::DNS::Resolver;

sub reverselookup($)
{
        my ($ip) = @_;
        my $search = $res->search($ip);
        foreach $rr ( $search->$answer)
        {
                my $type=$rr->type;
                if ($type eq "A")
                {
                        $host=$rr->address;
                }
                if ($type eq "PTR")
                {
                        $host=$rr->ptrdname;
                }
        }
}


&reverselookup("61.9.128.17");