Departing from Hanoi International Airport
Check-in for departures on foreign airlines usually takes place in "Lobby A" of the terminal building. Departures on Vietnam Airlines check in at "Lobby B". The entrances to domestic departures are at either end of the terminal building. Be sure to check your gate number and use the appropriate entrance. All international departures are reached through immigration, which is accessed at the center of the terminal.
Once you finish with passport control, there's a security check before you get to the departure lounge.