4. A communication method implemented by a computer, for relaying communication from an application operating on a terminal to a communication destination, the method comprising:switching a communication protocol for the communication from a first protocol to a Delay/Disruption Tolerant Networking (DTN) protocol in accordance with a connection condition with the communication destination for the communication;
detecting whether a notification of a completion of a specific communication is necessary for the application to continue the communication,
transmitting the notification to the application when the notification is detected as necessary in the detecting; and
notifying the terminal of a failure of the specific communication in cases when the notification has been transmitted to the application and the specific communication in the DTN protocol results in failure.