11/03/2026
Difference Between Classful and Classless Subnetting
Classful IP addressing follows the default subnet masks assigned to each IP class. In this method, the network is not further subnetted, and the default mask of the class is used.
Examples of Classful IP addresses:
10.64.3.51
Subnet Mask: 255.0.0.0 (/8)
172.18.91.33
Subnet Mask: 255.255.0.0 (/16)
Classless addressing (CIDR – Classless Inter-Domain Routing) allows networks to be subnetted using different prefix lengths, instead of relying on the default class masks. This provides more flexibility and efficient use of IP addresses.
Examples of Classless IP addresses:
10.3.5.23/12
172.18.91.33/18
In classless addressing, the /number indicates the prefix length, which defines how many bits are used for the network portion of the IP address.