What distinguishes classful addressing from classless addressing in IP allocation?

Classful addressing and classless addressing primarily differ in how they allocate and manage IP addresses. Classful addressing uses fixed subnet sizes, which means that the subnetting of IP addresses is predetermined based on distinct classes (A, B, C, etc.). This approach results in subnets of uniform size, which can lead to inefficiencies, particularly when a network does not fully utilize the allocated addresses.

On the other hand, classless addressing employs variable-length subnet masking (VLSM), allowing for a more flexible and efficient use of IP addresses. This method enables networks to create subnets of different sizes based on the specific needs of a network, significantly optimizing the use of the available address space.

Understanding this distinction is crucial for efficient network design and management, especially in scenarios where IP addresses are a limited resource. Classful addressing can lead to wastage of IP addresses, while classless addressing maximizes their usage by allowing for tailored allocation according to the size of the network.