{
    my $subs = {
        num => sub { $a <=> $b },
        cmp => sub { $a cmp $b },
    };
    for ( qw{ NS MX TXT HINFO SPF SRV A CNAME PTR } ) {
        if ( exists $dns_records{$_} ) {
            print_header("$_");
            my $sortby = $subs->{ uc $_ eq 'PTR' ? 'num' : 'cmp' }; 
            for my $rec ( sort { $sortby->() } @{$dns_records{$_}} ) {
                print $rec, "\n";
            }
        }
    }
}