A quick 101 on networking, IP addresses and subnets.
iP addresses on the Internet for the most part are PUBLIC ! otherwise you would NOT be able to block unwanted traffic.
IP blocking and firewalls
Firewalls perform Internet Protocol blocking to protect networks from unauthorized access. They are common on today's Internet. They control access to networks based on the IP address of a client computer. Whether using a blacklist or a whitelist, the IP address that is blocked is the perceived IP address of the client.