What is a defining feature of multicast messages?

Multicast messages are indeed characterized by their delivery to a select group of hosts rather than to all devices on a network or just one specific device. This allows for efficient use of network resources, as the same message can be transmitted to multiple recipients at the same time without overwhelming the entire network with unnecessary traffic.

In a multicast setup, hosts that want to receive a multicast message must join a specific multicast group. This ensures that only the designated recipients receive the message, in contrast to broadcasting, where the message is sent to every device regardless of whether they need it or not.

This selective delivery mechanism enables applications like streaming video or audio to multiple users, effectively minimizing bandwidth usage compared to methods that utilize either unicast (targeting one specific recipient) or broadcast (targeting all hosts).