Foundation Topics

Classful Network Concepts

Imagine that you have a job interview for your first IT job. As part of the interview, you’re given an IPv4 address and mask: 10.4.5.99, 255.255.255.0. What can you tell the interviewer about the classful network (in this case, the Class A network) in which the IP address resides?

This section, the first of two major sections in this chapter, reviews the concepts of classful IP networks (in other words, Class A, B, and C networks). In particular, this chapter examines how to begin with a single IP address and then determine the following facts:

• Class (A, B, or C)

• Default mask

• Number of network octets/bits

• Number of host octets/bits

• Number of host addresses in the network

• Network ID

• Network broadcast address