What does the Link or Network Interface layer do?

The Link or Network Interface layer is responsible for putting frames onto the physical network, which is fundamental to the process of communication between devices on the same local network or segment. At this layer, data packets are transformed into frames that include MAC (Media Access Control) addresses, enabling network devices such as switches and network interface cards to efficiently send and receive data over the physical medium, such as cables or wireless signals. By encapsulating data into frames, this layer ensures that the information is correctly packaged for transmission, allowing for effective data transfer within the local network environment.

The other options pertain to different layers of the networking model; for example, session management relates to establishing and maintaining sessions at a higher layer, while encryption is associated with security measures that usually occur at the transport layer or above. Routing across multiple networks is a function typically performed at the network layer, which deals with path determination and packet forwarding, a step that occurs after the Link layer has framed the data for transmission.