Switches build and maintain what kind of table?

• A. MAC address table
• B. IP routing table
• C. ARP table
• D. DNS cache

Answer: (A)

Switches operate at the data link layer and learn where devices live by recording the source MAC addresses of frames they receive. They build a MAC address table (also called a CAM table) that maps each MAC address to the switch port where that device can be reached. When a frame arrives, the switch looks up the destination MAC in this table and forwards the frame only to the appropriate port, which makes forwarding efficient and reduces unnecessary flooding. The entries are learned dynamically and age out after inactivity to keep the table current as devices move.

This differs from an IP routing table, which is used by routers to forward packets between networks; an ARP table, which maps IP addresses to MAC addresses on hosts and routers; and a DNS cache, which stores domain-to-IP mappings for name resolution. So the kind of table switches build and maintain is the MAC address table.