Abstract: Upon receiving an acknowledgement after retransmission of a data segment, an acknowledgement number contained in the acknowledgement is compared with an acknowledgment number expected to be contained in an acknowledgement pertaining to the retransmitted data segment. When the former is larger than the latter, it is determined that the acknowledgement pertains to a data segment that was originally transmitted.

Abstract: A first elapsed time from transmission of a data segment until receipt of an acknowledgement is measured. A probability distribution of the first elapsed time is generated for a client device 50 on the basis of the measured first elapsed time. A second elapsed time from retransmission of a data segment until receipt of an acknowledgement is measured. A probability distribution of the second elapsed time is generated for a client device 50 on the basis of the measured first elapsed time. An estimation is made as to whether an acknowledgment pertains to which data segment on the basis of the generated probability distribution.

Abstract: An object of the present invention is to provide an automatic detecting apparatus for protocol nonconformity in which protocol nonconformity can be detected without necessity of technical knowledge and complex operation.

Abstract: The present invention relates to a reception notification control method in which an information server that stores information addressed to reception terminals and performs reception notification, via a network apparatus, on each of the reception terminals to which the information stored in the information server is addressed. After receiving, via the network apparatus, a predetermined connection request from a reception terminal to which stored information is addressed, the information server performs the reception notification on the reception terminal.