What are A, B and C SEO Classes?¶

IP address format¶

An IP address, to be more preciese the version 4 of IP address protocol, is a unique identifier of 4 digits for a computer, a device or a network. Each digit is a number between 0 and 255. For instance, the IP address of Google's DNS server is 8.8.8.8 while the IP address of the DNS server for Cloudflare is 1.1.1.1.

One important aspect of IP address structure is that the numbers to the left define the range of an IP network.

For instance for 192.168.1.0/24, 192.68.1 defines a network with the range of IPs between 192.168.1.1 to 192.168.1.244 and 192.168.1.255 is most of the time reserved as broadcast IP, meaning any packets send to that address is going to be broadcasted to all the other computers in the network.

As another example, 10.0.0.0/8 defines a network with the range of IPs between 10.0.0.1 to 10.255.255.254 and the broadcast IP of 10.255.255.255.

Another observation we can make here is that the first network, which is a C class Network, has only 255 IPs while the second network, an A class network, has 255 * 255 * 255 = 16,777,215 IPs.

In the next section with review different IP classes.