A rural cooperative wants to deliver a live IPTV channel to every subscriber set-top box that has tuned in across a town, without sending a separate copy of the stream to each individual subscriber and without sending it to devices that never asked for it. Which traffic delivery type best fits this requirement?

Multicast delivery sends a single stream to a defined group of interested receivers, using group membership (rather than sending to every device or to one device at a time) to decide who gets a copy, which makes it the efficient fit for live IPTV distribution to only the subscribers who have joined that channel. Broadcast would deliver the stream to every device in the broadcast domain regardless of interest, wasting bandwidth on set-top boxes and other equipment that never tuned in and potentially overwhelming access links that weren't provisioned for that load. Unicast would require the head-end to originate a separate copy of the stream for every single subscriber, which does not scale as viewership grows and is precisely the inefficiency the cooperative is trying to avoid. Flooding is a Layer 2 switch behavior tied to unknown unicast destinations, not a traffic delivery category an engineer would choose for planned content distribution, and it does not involve any concept of group membership. An operational check for a cooperative rolling this out is confirming that set-top boxes only receive the stream after actively joining the multicast group and that non-member devices on the same segment show no measurable increase in traffic when the channel starts — evidence the delivery is genuinely group-scoped rather than broadcast to everyone.