Which mechanism prevents a switch from forwarding Layer 2 traffic from one broadcast domain to another?

Filtering is the mechanism that prevents a switch from forwarding Layer 2 traffic from one broadcast domain to another. In the context of Ethernet networks, switches are designed to operate at Layer 2 of the OSI model, which is responsible for forwarding frames based on MAC addresses. When a switch determines that incoming traffic belongs to a specific broadcast domain (or VLAN), it needs to apply filtering logic to ensure that traffic does not inadvertently cross over to another broadcast domain.

By filtering traffic, the switch can effectively limit the transmission of broadcast, multicast, or unicast frames to only those devices that exist within the same VLAN or broadcast domain, thereby preventing broadcast storms and enhancing network efficiency. This is important for maintaining traffic segmentation and ensuring that communication remains contained within its intended group.

Other mechanisms mentioned, such as BPDU guard, aging, and learning, serve different purposes in the context of network operation. BPDU guard is focused on enhancing the stability of spanning tree protocols by blocking ports that receive Bridge Protocol Data Units when a switch port is not expected to receive such messages. Aging pertains to the management of the MAC address table, determining how long addresses are cached before being removed if not in use. Learning is the process by which a switch builds its MAC address table by