online CIDR and IP subnet calculator : Check host

121.141.230.0-121.141.231.255
121.141.230.0/23

121.141.232.0-121.141.239.255
121.141.232.0/21

121.141.240.0-121.141.255.255
121.141.240.0/20

121.144.0.0-121.144.127.255
121.144.0.0/17

121.144.128.0-121.144.135.255
121.144.128.0/21

121.144.136.0-121.144.139.255
121.144.136.0/22

121.142.0.0-121.143.255.255
121.142.0.0/15

IP subnet calculator 121.141.230.0-121.144.139.255