If you configure firewall rules, then you need to allow/block a range of IP addresses.
One way to specify a range of IP address is to use IP address / CIDR suffix (e.g. 188.8.131.52/32)
The CIDR suffix can be confusing. So here is a quick reference table:
|CIDR||Effective IP Range||Total addresses|
|184.108.40.206/8||220.127.116.11 to 18.104.22.168||16,777,216|
|22.214.171.124./16||69.208,0.0 to 126.96.36.199||65,536|
|188.8.131.52/24||184.108.40.206 to 220.127.116.11||256|