What IAS does for us?

Internet Authentication server gives us RADIUS server. RADIUS stands for Remote
Authentication Dial in User Server, RADIUS is an industry standard.

Note: an IP address is assigned to every device that you want access on the network, and each have unique IP address. A client, server, every interface of router, printer and all devices on the network should have an IP address to communicate in the network.
Note: In class C address we have 254 clients for each subnet.
In class B address we have approximately 65,534 hosts per subnet.
In class A address we have millions of hosts per subnet.
Numbers can range from 0-255, but x.x.x.0 is used for identifying network and
x.x.x.255 is used for broadcasting, so we use the numbers from 1-254.
Note: The portion between two firewalls is called screened subnet, in corporate network we call it as DMZ (De Militarized zone).