What is multicast addressing?

Multicast is one-to-many: sent to a specific group of receivers who have joined that group — more efficient than sending many unicasts.

* Multicast: delivered only to hosts that joined the group. *

A multicast message is sent to a specific group of interested receivers.

Characteristics:

• One sender, multiple receivers
• Only group members receive the message
• More efficient than sending individual unicasts
• Receivers must "join" the multicast group

Examples:

• Video streaming to multiple viewers
• Stock market updates
• Online gaming (updates to nearby players)

Memory tip: Multicast = "MULTI" (many) - but only interested parties!

Go deeper:

• Multicast — one-to-group delivery and why it scales better than many unicasts.