There are two options. First - at the check-in counter at point A, you are immediately given out boarding passes for all the transfer points. Your luggage will also reach the final point of your flight. Second - at the front desk you get a boarding pass for the first part of the trip. In the next paragraph you will need to re-register for the flight. Baggage will proceed either to the final point or you will meet it at the transfer point and register again. In any case, the details need to be found out when registering for a flight at the airport.