1. A system comprising a plurality of dispatcher apparatuses which dispatch a transaction requested by an external terminal apparatus; a plurality of first-tier servers which process the dispatched transaction; and at least one second-tier server which processes a part of the transaction in response to a request received from the first-tier server, each of the dispatcher apparatuses comprises: a storage device which stores a status table indicating an operation status of each second-tier server; a transferring unit which transfers a transaction request received from the external terminal apparatus to a first-tier server selected from the plurality of the first-tier servers, in order to dispatch the requested transaction; a table generator which receives the operation status of each of the second-tier servers included in a transaction response corresponding to the transferred transaction request, which evaluates the operation status of each of the second-tier servers based on the received operation status, which generates a status table indicating the operation status of each of the second-tier servers, and which stores the status table in the storage device; a table transmitter which reads the generated status table from the storage device in response to the generation of the status table, and which transmits the status table to each of the first-tier servers; and a first table updating unit which updates the status table stored in the storage device by use of the received status table in response to the reception of the status table from any of the first-tier servers, and each of the first-tier servers comprises: a storage device which stores a status table indicating an operation status of each second-tier servers; a request transmitter which transmits the transaction request to the second-tier server in response to the reception of the transaction request transferred from the transferring unit of one of the dispatcher apparatuses, in order to cause the second-tier server to process a part of the requested transaction; a status returning unit which returns, to the dispatcher apparatus, the status of the transaction response to the transaction request transmitted to the second-tier server, as the operation status of the second-tier server, the status of the transaction response included in the transaction response to the transaction request transferred from the transferring unit of the dispatcher apparatus; a second table updating unit which updates a status table already stored in the storage device by use of the status table received from the table transmitter of the dispatcher apparatus, in response to the reception of the status table; and a table returning unit which returns the updated status table to each of the dispatcher apparatuses, in response to the update of the status table.