Which of the following isare true regarding router operation

Which of the following is/are true regarding router operation?

A. Routers work at Layer 3 only.

B. Routers work at Layers 1, 2, and 3 to accomplish their tasks.

C. Routers only examine Layer 3 addresses.

D. Routers must examine the Layer 2 address to accept the frame first, and then will look at the Layer 3 address.

Solution

B and D are correct. All devices must work at the Physical layer, and the router must also examine the Layer 2 address to determine if the frame is intended for it or not. After the frame’s physical address is verified, the router moves up to Layer 3 and examines the IP address.

A and C are incorrect. When a device is said to work at a given layer, it means the device works at all layers up to that level. Routers work at Layer 3; therefore, they perform functions at Layers 1 through 3.