IP Classful Addressing Network and Host Identification and Address Ranges
The classful IP addressing scheme divides the total IP address space into five classes, A through E. One of the benefits of the relatively simple classful scheme is that information about the classes is encoded directly into the IP address. This means you can determine in advance which address ranges belong to each class. It also means the opposite is possible: You can identify which class is associated with any address by examining just a few bits of the address. This latter benefit was one of the main motivators for the initial creation of the classful system.
Classful Addressing Class Determination Algorithm
When TCP/IP was first created, computer technology was still in ...