A bridge filtering packets based on MAC addresses operates at which OSI model layer?

A bridge operates at the Data Link layer (Layer 2) of the OSI model. This is the layer responsible for node-to-node data transfer and for handling error correction from the physical layer below it. Bridges specifically filter packets based on MAC (Media Access Control) addresses, which are unique identifiers assigned to network interfaces for communications at the Data Link layer.

By examining the MAC addresses of incoming packets, a bridge can determine whether to forward or filter packets to specific segments of a network. This capability helps in managing traffic, improving network efficiency, and reducing collisions by segmenting collision domains.

The other layers listed—Presentation, Session, and Application—serve different functions. The Presentation layer (Layer 6) deals with the format of the data (such as encryption and compression), the Session layer (Layer 5) manages sessions and controls dialogue between computers, and the Application layer (Layer 7) is where end-user software operates, facilitating user interactions with applications and services. Therefore, none of these layers involve packet filtering based on MAC addresses, reaffirming that the bridge's function aligns specifically with the Data Link layer.