ok well, i didnt know u had to go into very specific detail about how it works. but first modem is made up of two words.
modulate and
demodulate basicly meaning...it takes the digital sigle passed to it from say the router/computer and converts it into an analogue waveform, so it can be sent down ur tellecom lines etc... then it needs to do the opposite with incomming data...
i doubt ull need to know much more than that about modems...maybe the diffrent protocols....but i have no idea wat they are
so dont ask....
router: if they ask u a question about this, its usualy more like the diffrences between a router/switch/hub/gateway/bridge
first the router: basicly think of some guy trying to climb a mountain...he will have a router with him(a person)...and his job is to find the easiest way up the mountain....a computer router does the same for ur network, it will find a free path for transmittion and it will take that. (this is oftern associated with packet switching)
hub: a hub is a peice of networking hardware that will recieve data and resend it to ALL of the nodes attatched to it. ie. any data sent to a specific hub, will end up being sent to every node attatched to it, regardless of which node the data is addressed to.
Switch: is a smart hub basicly....this means that it will find who the data is addressed to, and will send it only to that node, this means that u can send more data at the same time, because a data line is only being used when the node is actualy being sent data.
now for gateway and bridge. i use a lil story again
say u have two paddocs: if u have sheep in 1 and cows in the other...u put a gate between the two paddocs so that they cows and sheep cant mix...
but if u have sheep in each one, u dont care if they mix....so u put a bridge so they can freely walk back and forth
same goes for networks....two of the same network is joined by a bridge
two networks of diffrent protocols are joined by a gateway.
soz if i went on a bit
hope it helps