What is a unique characteristic of MAC addresses?

MAC addresses are permanent and unique to network devices, serving as a fundamental means to identify devices within a local area network. Each network interface card (NIC) is assigned a unique MAC address, which is intended to be a long-term identifier for the device. This uniqueness ensures that data packets are directed to the correct hardware on the network, facilitating proper communication between devices.

While MAC addresses can sometimes be spoofed or changed through software (primarily for privacy or security purposes), the inherent design of MAC addresses is that they are meant to be stable and permanently tied to the hardware they are assigned to. This distinct characteristic distinguishes them from other addressing schemes that might regularly change based on device state or network dynamics.

In contrast, the other options wrongly attribute characteristics to MAC addresses that do not align with their intended function or usage. For example, the idea that they change frequently or are restricted to wireless networks misrepresents how MAC addresses operate across various types of networking environments.