What best describes the difference between an ARP table and a MAC address table?

• A. An ARP table maps IP addresses to MAC addresses.
• B. A MAC address table maps IP addresses to switch ports.
• C. An ARP table stores IPv6 addresses only.
• D. A MAC address table maps MAC addresses to VLAN IDs.

Answer: (A)

The main idea is that ARP tables and MAC address tables serve different functions in how devices locate each other on a local network. An ARP table is about resolving addresses: it stores mappings from IP addresses to MAC addresses so a host can encapsulate an IPv4 packet in an Ethernet frame with the correct destination hardware address. These mappings are learned dynamically through ARP requests and replies and are used when a host needs to send data to another IPv4 device on the same subnet.

A MAC address table, on the other hand, lives in switches and tells the switch which physical port to forward a frame to based on the destination MAC address. The switch learns these mappings by observing the source MAC of frames it sees, building a MAC-to-port map (often within the context of a VLAN). This speeds up forwarding and avoids broadcasting to all ports.

So the statement that ARP tables map IP addresses to MAC addresses is the best description because it captures the purpose of ARP: translating an IP address to the hardware address needed to actually deliver the frame. The other ideas mix up the roles: a MAC address table maps MAC addresses to switch ports (not IPs), ARP tables are not limited to IPv6, and MAC tables aren’t defined by VLAN IDs themselves.