The calculated distance (air line) between Droichead Nua and Dún Laoghaire is approximately 28 miles respectively 46 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Droichead Nua and Dún Laoghaire has been calculated here.
Air line (approximately)
46 kilometers
25 nautical miles