Which statement is true about classful IP addressing?

The statement regarding public address ranges being globally unique is accurate in the context of classful IP addressing. Public IP addresses are assigned by the Internet Assigned Numbers Authority (IANA) and are meant for external use, ensuring that they are unique across the entire internet. This uniqueness is crucial because it prevents conflicts that could arise if two devices on different networks were to have the same public IP address.

In this scenario, the other options do not provide the same level of correctness. For instance, class A addresses do indeed have a larger range compared to class C addresses, but the focus of the question is whether the statement is true regarding classful addressing in a broader context. Similarly, while a class C address can support up to 254 hosts, stating that it can accommodate 255 hosts is misleading because one address is reserved for the network itself and one for the broadcast address, making the maximum usable hosts 254. As for the role of an ISP analyzing the network portion of an address, it's true that ISPs manage and route public IP addresses, but the specific focus of this task is on the uniqueness rather than ISP functions.

Thus, the uniqueness of public address ranges stands out as the definitive characteristic in understanding classful IP addressing, reinforcing the importance of