Each of the IP address classes was designed for a particular size of net-
work. For more basic information about IP address classes, check out
the Webopedia site.
Each IP address also has a default subnet mask. The mask is used by the
computers and other devices on the network to determine which part of
an IP address provides network information and which part of the ad-
dress provides addressing information related to a particular computer.
The class subnets are as follows:
• Class A: 255.0.0.0
• Class B: 255.255.0.0
• Class C: 255.255.255.0
If you look at the subnet masks for each class, you can see that for a
Class A network, the IP address's first octet is masked by the subnet
mask (the 255) and so the network information found in the IP address
actually consists of the first octet. In a Class B network, the first two
octets are network information; in a Class C network, the first three oct-
ets are network information. With fewer octets devoted to actual IP ad-
dresses as you move from Class A to Class C, you can see why Class C
networks provide fewer individual IP addresses.
Public IP addresses allow computers and other devices to connect direc-
tly to the Internet. You don't actually need to worry about public IP ad-
dresses and your connection to the Internet. This is all taken care of by
your Internet service provider. Your WiFi router is dynamically assigned