Which device primarily operates at Layer 2 of the OSI model and forwards frames based on MAC addresses?

Which device primarily operates at Layer 2 of the OSI model and forwards frames based on MAC addresses?

• A. Hub
• B. Switch
• C. Router
• D. Bridge

Answer: (B)

Frames being forwarded by MAC addresses happen at the Layer 2 level, where devices learn and use the MAC address table to send traffic only to the correct port. A switch listens to each frame’s source MAC to build that table, then uses the destination MAC to decide exactly which port to forward the frame to. If it knows the destination, it sends it on a single port; if it doesn’t, it floods to all ports to learn where that device is. This selective, port-by-port forwarding is what makes a switch the primary Layer 2 device for frame switching. Hubs replay everything to all ports (no MAC-based forwarding, Layer 1). Routers operate at Layer 3, using IP addresses to route between networks. Bridges also work at Layer 2 and use MACs, but switches are the multiport, high-performance evolution of that function, designed specifically for efficient MAC-based forwarding across many ports.

Frames being forwarded by MAC addresses happen at the Layer 2 level, where devices learn and use the MAC address table to send traffic only to the correct port. A switch listens to each frame’s source MAC to build that table, then uses the destination MAC to decide exactly which port to forward the frame to. If it knows the destination, it sends it on a single port; if it doesn’t, it floods to all ports to learn where that device is. This selective, port-by-port forwarding is what makes a switch the primary Layer 2 device for frame switching. Hubs replay everything to all ports (no MAC-based forwarding, Layer 1). Routers operate at Layer 3, using IP addresses to route between networks. Bridges also work at Layer 2 and use MACs, but switches are the multiport, high-performance evolution of that function, designed specifically for efficient MAC-based forwarding across many ports.