Differences between unicast, multicast, and broadcast

Unicast: If unicast is used in an IP address, the source needs to establish an independent information transmission channel with each of the hosts that require information, and sends an independent copy of information for each Receiver.
Broadcast: in broadcast mode, Source sends the information to all hosts in the CIDR Block, regardless of whether or not the information is required. Information security cannot be guaranteed, and information in the same network segment may flood.
Multicast: In multicast mode, the Source only needs to send one piece of information, and the multicast distribution tree is established using the multicast routing protocol, the transmitted information is replicated and distributed only on network nodes that are as far away as possible from the multicast source. Multicast solves the problem of single-point sending and multi-point receiving with minimal network overhead. Compared with broadcast, broadcast can only be distributed in the same network segment, while Multicast can be transferred across network segments.
 
The PC automatically obtains the IP address through DHCP through broadcast. In the same vlan, the source MAC can broadcast in the form of 255.255.255.255.255, that is, all hosts in the LAN can receive broadcast frames from the source MAC.