← Back to the activity

Class 8 Computer Science — Addresses and names on a network

Read a machine's address, work out which machines share a network, and say what turns a name into an address.

Name: ________________________

  1. 1.Every address on one network begins 10.4.2, and the last number may be anything from 20 to 90. How many machines can that network hold?

  2. 2.Which of these is a name service's job rather than a router's?

    • a) Joining two different networks together
    • b) Choosing which network to hand a message on to next
    • c) Carrying a message out of the building
    • d) Saying which number belongs to a given name

  3. 3.Machines share a network when the first three of their four numbers match. Of the four numbers, which single one is the only thing telling two machines on one network apart? Answer with an ordinal such as second or third.

  4. 4.Someone types a name into a browser and the browser has never met that name before. Put these four things in the order they happen.

    • The name service answers with the number
    • The browser sends its request to that number
    • The browser asks a name service which number goes with that name
    • The browser is handed a name

  5. 5.Two different machines on one network are given the same address by mistake. What goes wrong?

    • a) Both machines stop working altogether until one is unplugged
    • b) Messages meant for one of them can arrive at the other, because the address no longer says which machine is which
    • c) Nothing goes wrong, because an address is allowed to be shared
    • d) The network runs more slowly, but everything still arrives where it should

  6. 6.An address is four numbers, and each of the four is held in one byte. How many bits long is a whole address?

  7. 7.A website is moved onto a different machine with a different address, and keeps the name it always had. What has to be changed so that people can still reach it?

    • a) The address of the computer belonging to each person visiting
    • b) The name itself, so that it matches the new machine
    • c) What the name service answers when it is asked about that name
    • d) Every browser in the world, one at a time

  8. 8.A machine's address is four numbers separated by dots, and every one of the four runs from 0 to 255. Which of these could never be a machine's address?

    • a) 100.200.50.25
    • b) 172.16.254.9
    • c) 10.0.0.1
    • d) 192.168.0.300

Answer key — Class 8 Computer Science — Addresses and names on a network

  1. 1. 71
  2. 2. d) Saying which number belongs to a given name
  3. 3.
    • fourth
    • the fourth
    • last
    • the last
  4. 4. 1. The browser is handed a name 2. The browser asks a name service which number goes with that name 3. The name service answers with the number 4. The browser sends its request to that number
  5. 5. b) Messages meant for one of them can arrive at the other, because the address no longer says which machine is which
  6. 6. 32
  7. 7. c) What the name service answers when it is asked about that name
  8. 8. d) 192.168.0.300