Click the [New Problem] button to start, then select the class of network.

IP Address
Class of Network
A B C D E  

The Class of a Network is based on the 'First Octet' rule.
Using this rule the network Class is determined by examining the bits in the first octet of the IP address.
This is shown in the table below under 'Binary Number' when you click [Check Answer].

Decimal Weight 1286432168421
Binary Number