CompTIA Network+ Practice Test

Which layer of the OSI model is responsible for data encapsulation and MAC addressing?

1. Data Link layer

2. Network layer

3. Transport layer

4. Session layer

The correct answer is: Data Link layer

The correct answer is the Data Link layer, which is the second layer of the OSI model. This layer is responsible for providing node-to-node data transfer and ensuring reliable communication over the physical network. One of its primary functions is to encapsulate data into frames, which includes adding the necessary headers and trailers that contain control information. In addition to encapsulation, the Data Link layer also manages MAC (Media Access Control) addressing. Every device on a local area network (LAN) has a unique MAC address, which is used to identify devices at the Data Link layer. This identification is essential for the correct delivery of frames to the intended recipient on a network, as MAC addresses are used to direct network traffic within the local network. The other layers have different roles: the Network layer is focused on routing data packets between devices across different networks, the Transport layer is responsible for end-to-end communication and flow control, and the Session layer manages sessions between applications. Each layer has distinct responsibilities, and it is the Data Link layer that directly deals with framing and MAC addressing, making it the correct answer in this scenario.