At which OSI layer is a source MAC address added to a PDU during the encapsulation process?
- data link layer
- application layer
- transport layer
- presentation layer
Answers Explanation & Hints: The source MAC address is added to a Protocol Data Unit (PDU) at the Data Link layer during the encapsulation process. The Data Link layer is the second layer of the OSI (Open Systems Interconnection) model and it is responsible for data framing, error detection, and media access control. The Data Link layer adds the source and destination MAC addresses to the PDU header, which is used by switches to forward the data to its destination. The Application layer is the top layer of the OSI model and it provides interfaces for application-level protocols. The Transport layer is responsible for end-to-end communication between processes running on different hosts. The Presentation layer is responsible for data formatting and conversion.