You do not need a transit visa
You do not need a transit visa to travel through an Irish airport on your way to another destination.
When you arrive at the airport in Ireland, you will not pass through border control. You will remain 'airside' of the border while you wait for your connection.
If you wish to pass through border control, you must prove that you have a valid reason for entering Ireland to an immigration officer.
In most circumstances, you will not be allowed to cross the border while you wait to transit.