Confirmation  is normally your responsibility. You have to confirm your flight, before your outbound and inbound journeys. Confirmation is best done directly with the airline 72 hours in advance of the flight time. This is particularly important with your return journey where failure to reconfirm can result in the in-validation of your ticket. Some airlines do not require you do this procedure, but it never hurts to contact whoever your flying with; in case of delays, time changes etc.