Disclosed is a method of determining a failure in an information system including a transmission apparatus for transmitting control information and a reception apparatus connected to the transmission apparatus in such a manner as to enable information to be transmitted and received for receiving the control information, the reception apparatus transmitting response information to the received control information, wherein the transmission apparatus obtains, as first clock time, clock time of the most recently transmitted control information if the response information to the control information cannot be obtained within predetermined time period, wherein the transmission apparatus obtains, as second clock time, later one of clock time of the response information most recently transmitted by the reception apparatus and clock time of the control information most recently received by the reception apparatus, and wherein the transmission apparatus determines failure location based on the first clock time and the second clock time.