At which OSI layer is a source IP address added to a PDU during the encapsulation process?
- network layer
- data link layer
- transport layer
- application layer
Answers Explanation & Hints: The source IP address is added to a Protocol Data Unit (PDU) at the Network layer during the encapsulation process. The Network layer is the third layer of the OSI (Open Systems Interconnection) model, and it is responsible for routing and forwarding data between different networks. The Network layer adds the source and destination IP addresses to the PDU header, which is used by routers to forward the data to its destination. The Data Link layer is responsible for data framing and error detection, while the Transport layer provides end-to-end data transport services and the Application layer provides interfaces for application-level protocols.