? For getting a static ip like google, facebook etc. etc. you have to pay heavy prices. Whenever the router connects to net, everytime a new unallocated ip is assigned to it. Its the global IP. Local IP depends upon the user, it can either be set manually or DHCP can be put into use. The local IPs too are among the public/free IP pool like 192.168.0.0 to 192.168.255.255, 10.0.0.0 to 10.255.255.255 etc. I hope it cleared the idea.