At which OSI layer would a logical address be added during encapsulation?

• A. Physical layer
• B. Data link layer
• C. Network layer
• D. Transport layer

Answer: (C)

Logical addressing is added at the network layer because that layer is responsible for routing packets between networks. During encapsulation, the network layer attaches an IP header containing source and destination addresses, which routers use to decide where to send the packet next. This is what enables inter-network communication.

In contrast, the data link layer handles local delivery on a single physical network by adding MAC addresses; the transport layer adds port numbers to support delivery to the correct application across a network, and the physical layer simply transmits the raw bitstream without addressing.