At which OSI layer do switches operate?

Switches primarily operate at the Data Link Layer of the OSI model, which is Layer 2. This layer is responsible for node-to-node data transfer and provides the protocols that allow for error detection and correction in the frame delivery process between directly connected devices. In this context, switches utilize MAC (Media Access Control) addresses to forward frames to the correct destination within a local area network (LAN). By examining these MAC addresses, switches create and maintain a MAC address table that helps in efficiently directing traffic without unnecessary broadcasting.

The other layers mentioned do not align with the functioning of switches. For instance, the Application Layer deals with high-level protocols and user interfaces, the Transport Layer is concerned with end-to-end communication and error recovery, and the Session Layer manages sessions between applications. Therefore, placing switches within the context of these other layers would misrepresent their core functionality in networking.