What is multicasting?[什麼是多播？]

資料來源:https://www.codeproject.com/Articles/7454/GroupTalk-A-multicast-based-group-conference-appli

we have to be familiar with the term multicasting. Let us start with unicasting and broadcasting. Unicasting is sending data to single host. Broadcasting is sending data to all hosts on the network. Multicasting lies in between these two. It is sending data to group of hosts. This group is identified by the multicast address.
[我們必須熟悉多播這個術語。 讓我們從單播和廣播開始。 單播是將數據發送到單個主機。 廣播正在向網絡上的所有主機發送數據。 多播介於這兩者之間。 它正在向主機組發送數據。 該組由多播地址標識。]

Every host on the network has an IP Address. IP Address is divided into 5 classes. Each class contains specific range of IP addresses.
[網絡上的每台主機都有一個IP地址。 IP地址分為5類。 每個類包含特定範圍的IP地址。]

IP位址分五種等級
    Class A >> 0.0.0.0 – 126.255.255.255 
    Class B >> 128.0.0.0 – 191.255.255.255 
    Class C >> 192.0.0.0 – 223.255.255.255
    Class D >> 224.0.0.0 – 239.255.255.255[群播/多播用途] 

    Class E >> 240.0.0.0 – 255.255.255.255[未定義]

Class D address is called multicast address. Each group on the network has unique multicast address associated with it. In order to create the group you can choose any address in Class D. Its safer to use any address starting from 225.0.0.0 to 239.255.255.255 since 224.*.*.* are generally used for the router and group management.
[D類地址稱為多播地址。 網絡上的每個組都具有與之關聯的唯一多播地址。 為了創建組，您可以選擇D類中的任何地址。使用從225.0.0.0開始到239.255.255.255的任何地址都更安全，因為 224.*.*.* 通常用於路由器和組管理。]