EPD Protocol Pilot Practice Test

A protocol state machine is a formal model that defines the set of states a protocol can be in and the allowed transitions between those states in response to events or messages. It describes how the protocol should move from one state to another, what triggers a transition, and what actions occur during that transition. This makes the intended behavior unambiguous and verifiable, helping designers catch illegal sequences and dead ends early. In the EPD Pilot, you would see states like idle, handshake, established, and finished, with transitions driven by events such as a request, a reply, a timeout, or a close, ensuring the protocol proceeds in a correct, predictable order. The other options describe tools or techniques that are not about modeling state progression.