Which layer receives the packets and adds MAC addresses to create a frame?

• A. Layer 2 Data Link
• B. Layer 1 Physical
• C. Layer 3 Network
• D. Layer 4 Transport

Answer: (A)

Wrapping a network-layer packet with MAC addresses to form a frame is the job of the Data Link layer. This layer takes the packet from the Network layer, adds a frame header with the destination and source MAC addresses, and appends a trailer (like a frame check sequence) to create a complete frame. Those MAC addresses are hardware identifiers used to deliver the frame on the local network segment, which is why framing happens here before moving down to the Physical layer for actual bit transmission. The Physical layer handles the electrical signals, not addressing. The Network layer, in contrast, adds IP addresses and routing information to create a packet for inter-network delivery. The Transport layer handles end-to-end communication concepts like ports and reliability.