A hub is a network device that repeats information received from a host to all other connects hosts. In Figure 1-2 the hub will relay any information received from HostA to HostB and HostC. This means that all the three hosts can communicate with each other. Communication between hosts can be classified into three types:
Unicast – Communication from one host to another host only.
Broadcast – Communication from one host to all the hosts in the network.
Multicast – Communication from one host to few hosts only.