A MAC address is

• A. A unique hardware address used to send and receive on layer 2 broadcast domains such as VLANs
• B. An IP address
• C. A DNS name
• D. A subnet mask

Answer: (A)

MAC addresses are unique hardware identifiers associated with a network interface, used at the data link layer to identify devices within the same local network segment. They travel inside Ethernet frames as the destination and source addresses, allowing switches to forward frames only to the correct port within a VLAN or other Layer 2 broadcast domain. Because the addresses are tied to the NIC, they remain with the device across the local network, and switches learn where each device lives by mapping MAC addresses to switch ports. Routers, which connect different broadcast domains, rely on IP addresses for routing between networks rather than sticking MAC addresses across boundaries. This makes a MAC address fundamentally different from an IP address, a DNS name, or a subnet mask.