What characteristic distinguishes 32-bit addresses from 128-bit addresses in network protocols?

The characteristic that distinguishes 32-bit addresses from 128-bit addresses in network protocols is indeed the size of the address. In networking, the size of the address directly affects how many unique devices can be addressed within a network.

With a 32-bit address, such as that used in IPv4, the maximum number of unique addresses available is approximately 4.3 billion (2^32). This limitation has led to the exhaustion of IPv4 addresses, prompting the adoption of IPv6, which utilizes 128-bit addresses. The larger size of the IPv6 address allows for an astronomical number of unique addresses, totaling 2^128, which can accommodate the growing number of devices connected to the internet.

Other choices, such as the type of media used for transmission, speed of packet delivery, and color coding of the address format, do not relate directly to the fundamental distinction between address sizes. These factors may influence network performance or implementation details but do not define the difference between 32-bit and 128-bit addressing in protocols. Understanding the significance of address size is crucial in grasping the evolution of networking technologies and the need for larger address spaces as the number of internet-connected devices continues to grow.