use Net::DLookup;

     # Initialize Net::DLookup object
     my $dlu = Net::DLookup -> new;

     # Replace domain definitions from a file
     $dlu -> LoadTLD($file, 1);

     # Add domain definitions from a file
     $dlu -> LoadTLD($file, 0);

     # Check domain name validity and assign it to the object
     @errors = $dlu -> IsValid($domain);

     # Return availability
     @response = $dlu -> DoWhois(0);

     # Return availability and registrar information
     @response = $dlu -> DoWhois(1);