What does a Layer 2 switch use to decide where to forward a received frame?

Question

Options

• Asource MAC address
• Bsource IP address
• Csource switch port
• Ddestination IP address
• Edestination port address
• Fdestination MAC address

• C
  4% (1)
• E
  4% (1)
• F
  93% (26)

Explanation

A Layer 2 switch forwards frames based on the destination MAC address (F) because its job is to deliver the frame to the correct device on the local network - it looks up the destination in its MAC address table and sends the frame only out the matching port.

Why the distractors are wrong:

• A (source MAC) - the switch learns from the source MAC to build its table, but uses the destination MAC to make forwarding decisions.
• B (source IP) / D (destination IP) - IP addresses are Layer 3 concerns, handled by routers, not Layer 2 switches.
• C (source switch port) - ports are used to record where a device lives during learning, not to decide where to send traffic.
• E (destination port address) - port numbers (TCP/UDP) are Layer 4; a Layer 2 switch is blind to them.

Memory tip: Think "Layer 2 = MAC, destination = delivery." Just like a postal worker reads the destination address on an envelope to know where to deliver it, a switch reads the destination MAC to know which port to forward the frame out of.

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