Which statement describes the correct direction of encapsulation when a PC sends data to the network in TCP/IP?

• A. Data is sent from the internet layer to the network access layer.
• B. Packets are sent from the network access layer to the transport layer.
• C. Segments are sent from the transport layer to the internet layer.
• D. Frames are sent from the network access layer to the internet layer.

Answer: (C)

In TCP/IP, encapsulation happens as data moves downward through the stack, with each layer wrapping the data in its own header and handing it to the next lower layer. The transport layer creates a segment, and this segment is then passed to the internet layer to be encapsulated inside an IP datagram. This first downward step—segments moving from the transport layer to the internet layer—is the correct description of how data is encapsulated when a PC sends data to the network.

So the best statement is that segments are sent from the transport layer to the internet layer. The other ideas describe later steps or mix up the units used at each layer (frames are created at the network access layer, not passed upward to the internet layer).