Which OSI layer is responsible for encapsulating a PDU with port numbers for transport-layer protocols?

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Multiple Choice

Which OSI layer is responsible for encapsulating a PDU with port numbers for transport-layer protocols?

Explanation:
Port numbers are used to identify specific applications on a host and are added by the transport layer to enable multiplexing multiple conversations. When data from an application moves down the protocol stack, the transport layer encapsulates it into a segment (TCP) or datagram (UDP) and includes source and destination port numbers in the header. This allows end-to-end communication between processes across hosts. The network layer below handles IP addresses for routing, while the data link layer handles MAC addressing on the local link. So the encapsulation with port numbers occurs at the transport layer.

Port numbers are used to identify specific applications on a host and are added by the transport layer to enable multiplexing multiple conversations. When data from an application moves down the protocol stack, the transport layer encapsulates it into a segment (TCP) or datagram (UDP) and includes source and destination port numbers in the header. This allows end-to-end communication between processes across hosts. The network layer below handles IP addresses for routing, while the data link layer handles MAC addressing on the local link. So the encapsulation with port numbers occurs at the transport layer.

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