Which description correctly matches unicast, multicast, and broadcast addresses?

• A. Unicast delivers to a single host on any network; multicast delivers to a group subscribed to a multicast group; broadcast delivers to all hosts on the local network.
• B. Unicast delivers to a single interface; multicast delivers to a group subscribed to a multicast group; broadcast delivers to all hosts on the local network.
• C. Unicast delivers to a broadcast domain; multicast delivers to a single interface; broadcast delivers to all hosts on the internet.
• D. Unicast delivers to all hosts; multicast delivers to all hosts in a group; broadcast delivers to a subset.

Answer: (B)

The idea being tested is how delivery scopes differ for IPv4 addresses: unicast targets a single recipient interface, multicast targets a group of receivers that have joined a multicast group, and broadcast reaches all hosts on the local network segment.

Why this option is best: Unicast delivers to a single interface, which is the precise way to send to one device on a network, even if that device has multiple interfaces. Multicast delivers to a group subscribed to a multicast group, so only members of that group receive the traffic. Broadcast delivers to all hosts on the local network, and routers generally don’t forward those frames beyond the local subnet.

Context to help understanding: A device can have multiple interfaces, so saying “single interface” is more accurate than “single host.” Multicast relies on group membership (IGMP/MLD in IPv4/IPv6) to determine which subnets should receive traffic. Broadcast is constrained to the local network; it is not meant to reach devices across the Internet, which is why the idea of broadcasting to all hosts on the Internet is incorrect.

The other descriptions blur these scopes (for example, implying unicast is to a single host across any network, or stating broadcast can reach the Internet), which misses the precise delivery rules.