The calculated distance (air line) between Dolzhanskaya and Rostov-na-Donu is approximately 100 miles respectively 160 kilometers.
By car or train, the actual journey to Rostov-na-Donu is certainly longer, as only the direct route (as the crow flies) between Dolzhanskaya and Rostov-na-Donu has been calculated here.
Air line (approximately)
160 kilometers
86 nautical miles