With reference to [Ethernet], a broadcast is defined as a packet that will be sent to all hosts in the broadcast domain (the area between routers/switches).



A broadcast is addressed to a [MAC] of FF:FF:FF:FF:FF:FF, (equivalent to a  [subnet] mask of 255.255.255.255)



A broadcast domain is only able to be segregated by OSI layer 3 devices (routers). In effect, if a host is on the same network/[subnet] it will receive any broadcast sent on that network. However, the boundary between layer 2 and 3 is blurred by VLAN Switches - which also separate broadcast domains.



{http://www.gummay.net/images/broadcast.jpg Broadcast!}

'''Diagram 1:''' In this situation, server has sent a broadcast to the network. Each workstation receives a copy.



Related to Broadcast, Multicast is simply a broadcast where the data packet is not sent back to the source port. Where a hub broadcasts, a switch multicasts. For example, OSPF Designated routers multicast link state advertisements to all other OSPF routers in the area using the multicast address of 224.0.0.5.





On the other hand, a unicast is simply transfer from one source to a single destination.



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It appears from my quick readings that we have:

 * Ethernet broadcast 

 * Limited broadcast

 * Directed broadcast

It may be worth expanding each of these into their own subsection, especially as we are dealing with multiple subnets in our network.



This (http://waitaki.otago.ac.nz/telecom/tele402/lectures/lecture-15-ho.pdf pdf) appears to be a reasonable overview.



I've made a couple of changes to your original, revert them if need be.