what is exponential back-off?

Answer 1

Exponential backoff is an algorithm that uses feedback to multiplicatively decrease the rate of some process, in order to gradually find an acceptable rate. It is often used in network congestion avoidance to help determine the correct sending rate. For example, a sender might send a message, set a timer to wait 0.25 seconds for an acknowledgment, and if none arrives, retransmit the message and wait 0.5 seconds for an acknowledgment. It will continue to retry until it receives an acknowledgement and will wait, 1s, 2s, 4s, 8s, etc. each time before retrying.