What is used to send information from one Layer 2 interface to another Layer 2 interface?

• A. IP Address
• B. Port Number
• C. VLAN ID
• D. MAC Address

Answer: (D)

The mechanism at work here is MAC addressing. At Layer 2, frames carry a destination hardware address (the MAC address) that identifies the exact device on the local network interface to deliver to. Switches use this destination MAC in the Ethernet frame header to forward the frame out the appropriate port toward that device, building a MAC address table to know where each device is reachable.

IP addresses operate at Layer 3 and are used to route packets between networks, not to deliver frames between interfaces on the same Layer 2 segment. Port numbers belong to the transport layer and identify applications, not endpoints on the local link. VLAN IDs are for separating traffic into virtual LANs and controlling scope, not for delivering a frame to a specific NIC on the same Layer 2 network.

So, to send information from one Layer 2 interface to another on the same network, the destination MAC address is what enables the correct delivery.