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Grade 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.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.

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

  4. 4.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) 192.168.0.300
    • b) 172.16.254.9
    • c) 100.200.50.25
    • d) 10.0.0.1

  5. 5.Each of the four numbers in an address is held in one byte, so it runs from 0 up to the largest value one byte can hold. Which point on the line is that largest value?

    Mark the line with an X.

    0306090120150180210240270

  6. 6.Two machines share a network when the first three of their four numbers are the same. Each of these machines is sending to the machine at 192.168.4.9. Sort each sender by whether its message stays on one network.

    Groups: Stays on one network · Crosses to another network

    • 192.168.4.40
    • 10.0.4.9
    • 192.168.4.200
    • 192.168.7.40
    • 172.16.4.9
    • 192.168.4.1

  7. 7.Machines share a network when the first three of their four numbers match. Match each machine to the network it is on.

    • 192.168.1.7
    • 192.168.2.7
    • 10.1.1.7
    • 172.16.5.7
    • 10.1.2.7
    • 192.168.2
    • 10.1.1
    • 172.16.5
    • 10.1.2
    • 192.168.1

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

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

  1. 1. 71
  2. 2.
    • fourth
    • the fourth
    • last
    • the last
  3. 3. 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
  4. 4. a) 192.168.0.300
  5. 5. 255
  6. 6. 192.168.4.40 → Stays on one network; 192.168.7.40 → Crosses to another network; 192.168.4.200 → Stays on one network; 10.0.4.9 → Crosses to another network; 192.168.4.1 → Stays on one network; 172.16.4.9 → Crosses to another network
  7. 7. 192.168.1.7 → 192.168.1; 192.168.2.7 → 192.168.2; 10.1.1.7 → 10.1.1; 172.16.5.7 → 172.16.5; 10.1.2.7 → 10.1.2
  8. 8. a) What the name service answers when it is asked about that name