Router switching function encapsulates the packets in the appropriate ______ type for the outgoing interface.

• A. Data link frame
• B. IP packet
• C. Network packet
• D. Physical frame

Answer: (A)

The key idea is encapsulation at the data link layer. When a router forwards an IP packet, it doesn’t send the packet as-is; it wraps (encapsulates) the IP packet inside a data link frame that matches the outgoing interface’s technology (for example, an Ethernet frame or a PPP/HDLC frame). This frame adds the appropriate data link header (like a destination MAC) and trailer, so the packet can traverse the next hop over the physical medium. The IP packet is the payload inside that frame, not the container itself. A data link frame is the correct container, while a network packet is a broader term and a physical frame isn’t the standard designation.