What are different classes of IP addresses?¶

In the previous section we have reviewed the IP address structure and learned that and IP address is a combination of network and host.

The network section of the IP is section that is common among all IPs within that network.

In the early days of the internet the routers were not as powerful as today and as a result the concept of the netwrok section and length of each network was agreed upon and that is how the concept of different classes were born.

Let's first see what the original classes were but we need to remind ourselves that these classes are not the ones we refer to today when it comes to search engine optimization.

In the early days of the internet routers did not have powerful processing powers and needed a relatively easy to implement method of routing.

The concept of the network section and length of each network was agreed upon and that is how the concept of different classes were born. The concept which we is now called classful IP addresses.

Classful IP addresses¶

When it comes to classful IP addresses the following classes were hardcoded in each router:

Class A: IP is from 1.x.x.x – 126.x.x.x with the first octed being the network octed.
Class B: 128.0.x.x – 191.255.x.x This time the first 2 octeds are the network section.
Class C: Here the IP range used to be from 192.0.0.x to 223.255.255.x. Obviously here the first 3 octets are network and only the last remaining is the host IP.

Of course there were other classes but those were not used for routing.

Classless IP addresses¶

As Internet grow exponentially we soon realized that the number of IPs that are assigned for public use are very limited. There were networks with millions of unused IPs while there were many ISPs desperately trying to allocate more IPs.

To solve this problem the concept of classless IP addresses was introduced. In classless IP addresses, the subnet mask of each IP defines the network section and the host IP is the remaining part of the IP.

In the next section we will talk about modern day SEO IP classes and how it is related to SERP ranking.