How a computer network works

1. Vocabulary focus. Sudy the words andword combinations, practise their translation, spelling. Check your knowledge in the test. Play vocabulary game and set your own vocabulary game record.

 

2.  Watch the video and put the words into the gaps in the text

Each (1)____ is limited in its size. The mail-room must decide how to divide the information and how to (2)____ it. Every package needs a (3)___, containing important information such as sender’s address, receiver’s (4)____ and the type of packet (5)___. Because this particular packet is going out onto the Internet, it also gets an address for the (6)____ which has a special function as we'll see later. The packet is now (7)____ onto your local area network or (8)____. This (9)____ is used to connect all the local computers, (10)____, (11)_____ etc. for information exchange within the physical walls of the building. The highway of the LAN is packed with all types of information. These are IP packets, Novell packets, Apple Talk packets. The local router reads the address and if necessary lifts the packet onto another network. As the packets leave the router, they make their way into the corporate (12)____ and head for the router (13)____. As packets arrive at their destination they are picked up by the network (14)____, ready to be sent to the next level, in this case, the proxy. The proxy is used by many companies as a sort of (15)____ in order to lessen the load on their Internet connection and for security reasons as well. The (16)____ opens the packet and looks for the web address or URL. Depending upon whether the address is (17)_____ the packet is sent on to the Internet. There are, however, some addresses which do not meet with the (18)____ of the proxy, that is to say corporate or management guidelines. These are summarily dealt with. For those who make it, it's on the road again. Next up - the (19)____.	package
	proxy server
	IDS
	address
	packet
	label
	routers
	middleman
	intranet
	switch
	network
	interface
	launched
	LAN
	printers
	acceptable
	proxy
	firewall
	approval

The corporate firewall serves two purposes. It prevents some rather (20)____ things from the Internet from coming into the intranet. And it can also prevent sensitive corporate (21)____ from being sent out to the (22)____. Once through the firewall, a router picks up the packet and places it on to a much narrower road or (23)____, as we say. Obviously, the road is not (24)_____ enough to take them all. Now you might wonder what happens to all those packets which don't make it along the way. Well, when IP doesn't receive an (25)___ that a packet has been received in due time, he simply sends a replacement packet. We are now ready to enter the world of the Internet, a (26)____ of inter-connected networks which spans our entire (27)____. Here, routers and switches establish links between networks. The paths our packets take maybe via (28)____, telephone lines, (29)____ or even trans-oceanic cable. Near the end of our destination, we'll find another firewall. The firewall is designed to let in only those packets that meet its (30)____. This firewall is operating on ports 80 and 25. Port 25 is used for mail packets, while port 80 is the entrance for packets from the Internet to the Web (31)____. Inside the firewall, packets are screened more (32)____, some packets make easily through customs while others look just a bit dubious. For those packets lucky enough to make this far, the journey is almost over. It's just to line up on the (33) to be taken up into the web server. One by one, the packets are received, opened and (34)____.	information
	Internet
	broad
	bandwidth
	nasty
	globe
	acknowledgment
	server
	wireless
	spider web
	criteria
	satellite
	thoroughly
	unpacked
	interface

 

3. Answer the questions.

1. What information does label contain?

2. What is local area network or LAN used for?

3. What is proxy used for?

4. What purposes does corporate firewall serve?

5. What are the assignments of ports 25 and 80?  

4. Mark the following statements as True or False.

1.     Each packet is unlimited in its size.

2.     Every package needs a label, containing important information.

3.     The highway of the LAN is packed with only IP packets.

4.  The proxy is used by many companies as a sort of middleman in order to increase the load on their Internet connection.

5.     The proxy opens the packet and looks for the web address or URL.

6.     Next level after proxy is the firewall.

7.     When mister IP doesn't get an acknowledgment that a packet has been received i n due time, he simply sends a replacement packet.

8.     Our packets are transferred only via telephone lines.

9.     Firewall is operating on six ports. 

10.  Inside the firewall, packets are screened more thoroughly, some packets make easily through customs while others look just a bit dubious.