The calculated distance (air line) between Cill Airne and Dún Laoghaire is approximately 165 miles respectively 266 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Cill Airne and Dún Laoghaire has been calculated here.
Air line (approximately)
266 kilometers
143 nautical miles