CCNA: Cisco Certified Network Associate — Question 107

For what two purposes does the Ethernet protocol use physical addresses?

Answer options

• A. to uniquely identify devices at Layer 2
• B. to allow communication with devices on a different network
• C. to differentiate a Layer 2 frame from a Layer 3 packet
• D. to establish a priority system to determine which device gets to transmit first
• E. to allow communication between different devices on the same network
• F. to allow detection of a remote device when its physical address is unknown

Correct answer: A, E

Explanation

The correct answers, A and E, highlight that physical addresses uniquely identify devices at Layer 2 and enable communication between different devices on the same network. Options B and F are incorrect because they refer to inter-network communication and detection of unknown addresses, which are not functions of physical addresses in Ethernet. Option C addresses frame and packet differentiation, while D discusses transmission priority, neither of which relate to the purpose of physical addresses.