Yes, it is A class. Unlike the rest of the world where the front cabin of a 2 cabin plane is business class the front cabin on US domestic 2 cabin plane is first class, accruing 50% mileage first class bonus instead of 25% business class. For example if I book a flight from DCA via MIA to SJO in Business or First, the domestic sebment from DCA to MIA I earn 50% FC bonus and the international segment from MIA to SJO I earn 25% BC bonus. Now, I am not sure about the DONE fares since AA says you earn points for the fare you purchased, so in that case you might only earn 25% bonus for the A service recieved on domestic US flights.