I am travelling to USA from India & returning, on Qatar Airways.
Dublin is a transit layover for two hours.
Is there any requirement for transit visa at Dublin?
As per the Irish Immigration Service, you don't need to apply for Irish Transit VISA, if you are not travelling on passport from the list of countries provided here. As per this list only 15 countries passport holder need to apply for Irish transit visa for their travel through Ireland. Just you need to have your USA visa stamped on your passport and confirm ticket for the connecting flight.