What does a switch keep track of?

What does a switch keep track of?

• A. MAC addresses attached to each port.
• B. IP addresses assigned to devices on the network.
• C. Usernames of connected devices.
• D. URLs of websites accessed by devices.

Answer: (A)

Switches operate at the data link layer and keep a MAC address table that maps each learned MAC address to the port it was seen on. As frames arrive, the switch notes the source MAC and the ingress port, building this table over time. When a frame needs to be forwarded, the switch checks the destination MAC in the table and sends the frame only to the corresponding port; if the destination MAC isn’t known yet, the switch floods the frame to all ports in the same segment. This behavior is what makes switching efficient and minimizes unnecessary traffic. The switch doesn’t track IP addresses, usernames, or website URLs for forwarding—that’s handled by higher-layer devices or services. (Entries in the MAC table can age out if a device stops communicating, allowing the switch to relearn the topology.)

Switches operate at the data link layer and keep a MAC address table that maps each learned MAC address to the port it was seen on. As frames arrive, the switch notes the source MAC and the ingress port, building this table over time. When a frame needs to be forwarded, the switch checks the destination MAC in the table and sends the frame only to the corresponding port; if the destination MAC isn’t known yet, the switch floods the frame to all ports in the same segment. This behavior is what makes switching efficient and minimizes unnecessary traffic. The switch doesn’t track IP addresses, usernames, or website URLs for forwarding—that’s handled by higher-layer devices or services. (Entries in the MAC table can age out if a device stops communicating, allowing the switch to relearn the topology.)