In one embodiment, a method includes iteratively waiting for a time interval; sending a keep-alive message from a first computing device to a second computing device; and incrementing a current value of the time interval when the first computing device receives from the second computing device a response to a current keep-alive message sent during the current iteration, until the first computing device does not receive from the second computing device any responses to the current keep-alive message sent during the current iteration; and setting the current value of the time interval to a previous value of the time interval from an immediately-previous iteration.