Classes in Subnet

Classes
There are three main types of classifications of IP addresses in IPv4: class A, class B, and class C. There are class D and class E types, but those are for multicasting and private uses, respectively. Each class differs by the number of network and host octets it has. Each network octet is for classifying which network a host is on. More network octets will mean more networks! Likewise, each host octet specifies a host that can be assigned to the network. More host octets means more computers per network.
Each class has a certain range that the first octet can be assigned to. This lets us know to what network class any IP belongs to with ease. Review the diagram below to see a visual diagram.

Now the bad news: you must memorize each range for each class if you hope to pass most network exams. Don’t worry! It’s actually easy- just memorize how we get the numbers, not the numbers themselves! All you have to do is remember n^8 (read as “n” to the eighth power), and how many network portions each class has. Review the diagram below.

One final note before we move on. Notice how we didn’t use the IP address 127 for the class A network- that’s because this is loopback address. We use this for testing configurations on the IP network. Also take note that there are reserved IP addresses, such as those for private networks. These IP addresses will not connect to the internet, which is handy if you just want computers to be connected with each other- and not the whole world.