What types of addresses are stored in a computer's ARP cache?

The ARP (Address Resolution Protocol) cache is a vital component used in networking to map IP addresses to MAC addresses. An entry in the ARP cache typically contains the IP address of the host as well as its corresponding MAC address. This mapping allows devices on a local network to communicate effectively without needing to continually broadcast requests to discover the MAC address of an IP.

This correspondence is essential, as data packets at the link layer are sent using MAC addresses, while higher-level communication uses IP addresses. By keeping this mapping in memory, the ARP cache enhances network efficiency by reducing the amount of broadcast traffic and speeding up the communication process.

The other address types mentioned in the other choices do not directly correlate with what is stored in the ARP cache. For example, a subnet mask is used for IP network addressing but is not relevant to MAC address resolution. Similarly, a default gateway serves as a routing path for traffic that is destined for networks outside the local one, rather than a resolution between IP and MAC addresses. Domain names relate to URL resolution and are typically handled by DNS, not ARP. Thus, the correct response highlights the primary function of the ARP cache in the networking context.