for ( qw{ NS MX TXT HINFO SPF SRV A CNAME PTR } ) {
    if ( exists $dns_records{$_} ) {
        print_header("$_");
        my $sortby = setsort($_);
        for my $rec ( sort $sortby @{$dns_records{$_}} ) {
            print $rec, "\n";
        }
    }
}

sub setsort {
    my $type = shift;
    return sub { $a <=> $b } if ( uc($type) eq "PTR" );
    return sub { $a cmp $b };
}