What detects any transmission errors while asynchronous communication?

What is false about the parity bit while asynchronous communication?

What means a long sequence of high level bits while asynchronous communication?

What is false about synchronous communication?

Which network layer is responsible for communication between any two processes, regardless of the machines on which they run?

Which network layer is responsible for communication between machines that are not physically connected?

Which network layer is responsible for the lowest level of communication, between machines that are physically connected?