Unicast Addressing
Unicast delivery requires that a message should be addressed to a specific recipient. This is the most common type of messaging, so this addressing capability is present in almost all protocols.
Broadcast Addressing
Broadcasts are normally implemented via a special address that is reserved for that function. Whenever devices see a message sent to that address, they all interpret it as “This message goes to everyone.”
Multicast Addressing
Multicasts are the most complex type of message because they require a means of identifying a set of specific devices that will receive a message. It is often necessary to create several such groups, which may or may not partially overlap in their membership. Some mechanism is needed to manage which devices are in which groups.
Anycast message
A new type of message-addressing method was defined as part of IP version 6 (IPv6): the anycast message. This term identifies a message that should be sent to the closest member of a group of devices.
