Which of the following controls network traffic based on MAC addresses?

A switch is the network device that controls and forwards traffic primarily based on MAC addresses. In CompTIA A+ Core 1 networking, a switch operates at Layer 2 (Data Link) of the OSI model. When devices communicate on an Ethernet LAN, the switch learns the source MAC addresses from incoming frames and stores them in a MAC address table (CAM table) along with the port where each device is connected. After learning, the switch uses the destination MAC address in each Ethernet frame to decide which specific port should receive the traffic, which reduces unnecessary transmissions and improves overall network efficiency compared to a hub. If the destination MAC is unknown, the switch will flood the frame out other ports (except the one it came in on) until it learns the correct location.

A router makes forwarding decisions using IP addresses at Layer 3, not MAC-based switching decisions. A PoE injector only supplies electrical power over Ethernet and does not manage traffic forwarding. A firewall filters traffic based on rules (IP, ports, protocols, and sometimes application/state), but the classic CompTIA A+ answer for MAC-based traffic control on a LAN is a switch.