Grade 8 Computer Science — The boxes that make a network work
Work out what a hub, a switch, a router, a modem and an access point each do, and choose the one a job needs.
Name: ________________________
1.A hub copies every message out to every other machine plugged into it. Four computers are on one hub, and each of the four sends one message. How many copies arrive at machines altogether?
2.A home has one box that joins its computers to each other, hands messages on to the outside world, and plugs into the line coming into the house. Someone says the home therefore has no modem. What is wrong with that?
- a) A box that joins computers to each other can never plug into a line
- b) A home has no need for a modem at all
- c) One box can do several jobs at once, and the part talking to the line is doing a modem's job
- d) A modem and a router are two names for exactly the same job
3.Two computers stand in the same room and are plugged into the same switch. One sends the other a file. Does the file pass through the router at the edge of the building?
- a) Yes — every message a computer sends passes through the router
- b) No — a message between two computers uses no device at all
- c) Yes, because the router holds the list of which machine is which
- d) No — both machines are on the same network, so the switch can deliver it by itself
4.Ten computers are plugged into one hub, which copies every message out to every other machine. The hub is swapped for a switch, which sends a message only to the machine it is addressed to. One computer now sends one message. How many fewer copies leave the device than before?
5.A school has two buildings, and each building has a network of its own. Messages now need to travel between the two. Which device does that job?
- a) A longer cable and nothing else
- b) A switch
- c) A router
- d) A hub
6.A lab with twenty machines has its hub taken out and a switch put in its place, and everything suddenly runs faster. What is the reason?
- a) A switch is built with thicker cables than a hub is
- b) A switch keeps a copy of every message so nothing ever needs sending twice
- c) Far fewer copies of each message are being put on the cables, so there is less traffic to get through
- d) A switch sits closer to the machines than a hub does
7.Match each device to the job it does.
- A hub
- A switch
- A router
- A modem
- An access point
- Delivers a message to the one machine it is addressed to
- Hands messages on between two different networks
- Turns signals into a form that can travel down the line to the outside world
- Lets a device with no cable of its own join the network
- Repeats everything it hears out to everything plugged into it
8.A message is sent from a computer in a lab to a machine on a network far away. Put these in the order the message reaches them.
- The switch that computer is plugged into
- A network outside the building
- The computer that sends the message
- The router at the edge of the building
Answer key — Grade 8 Computer Science — The boxes that make a network work
- 1. 12
- 2. c) One box can do several jobs at once, and the part talking to the line is doing a modem's job
- 3. d) No — both machines are on the same network, so the switch can deliver it by itself
- 4. 8
- 5. c) A router
- 6. c) Far fewer copies of each message are being put on the cables, so there is less traffic to get through
- 7. A hub → Repeats everything it hears out to everything plugged into it; A switch → Delivers a message to the one machine it is addressed to; A router → Hands messages on between two different networks; A modem → Turns signals into a form that can travel down the line to the outside world; An access point → Lets a device with no cable of its own join the network
- 8. 1. The computer that sends the message 2. The switch that computer is plugged into 3. The router at the edge of the building 4. A network outside the building