Differences Between Multicast and Broadcast

reviewed from the
·Multicast must communicate with a specific address.
"·Broadcasts must be communicated by specifying a specific ""network""."
That's it.

For the convenience of communicating with a specific address, multicast can
all
within the same segment. Not intended

For example, broadcasting is a disaster prevention broadcast that can be heard throughout 〇 町 town.
Multicast is like a circulation board or a membership broadcast that can only be communicated to members of 〇 町machi△△kai.

With that in mind, I will answer your questions.

■Question 1

(Without IGMP snooping)

The assumption that IGMP snooping is not used is a little incomplete.
マルチIf the multicast group members are not properly defined されて would be correct.

If the multicast group members are not properly defined, they are distributed to all ports because they cannot determine exactly which ports are members.
If the definition is correct, it is distributed only to ports that belong to a multicast group.

I IGMP snooping is a feature that allows the switch to automatically determine whether a multicast group is joined or left, and to make appropriate transfers, but you can also manually define members without using this feature.

Broadcasts are distributed across all ports because they are expected to be distributed simultaneously within the same network.

■Question 2

During the investigation, the word "flooding" appeared, but I understood that flooding means throwing it to all ports if the MAC address cannot be resolved.

Frames that are not listed in the switch's own MAC address table are flooded because they are delivered to all ports in the hope that someone who receives them will handle them properly.

In the case of broadcasts, it's intentional all-port distribution, so why don't we call it flooding?

Broadcasts should be distributed simultaneously, so they are not flooded.
All port forwarding in this case is called 言いますbroadcasting 」

Similarly, for multicast, can I call it flooding?

In the case of multicast or unicast, if not properly defined as described above, it is "flooded" because it has to be forwarded to all ports.