Reverse lookup brute force

checking live IP against que.com domain. // the prefix $ is the kali linux prompt. $ for ip in $(seq 50 100) do host 78.30.10.$ip; done | grep -v "not found" // This will display the reverse lookup found using the target IP, grepping without the "not found" 51.20.30.70 52.20.30.70 53.20.30.70 . . 100.20.30.70