The calculated distance (air line) between Rostov-na-Donu and Krymsk is approximately 179 miles respectively 289 kilometers.
By car or train, the actual journey to Krymsk is certainly longer, as only the direct route (as the crow flies) between Rostov-na-Donu and Krymsk has been calculated here.
Air line (approximately)
289 kilometers
156 nautical miles