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S6 ICT: Networking and Data Transmission – Practice Paper 4 (Error Retry, 10 Questions)
S6 ICT: Networking and Data Transmission – Practice Paper 4 (Error Retry, 10 Questions)
Paper four repairs the eight times slip: reading Mbps as MB per second, taking GB as Mb, counting all 256 addresses of a slash 24 as hosts, and treating 32 addresses of a slash 27 as 32 hosts.
Quick answer A 500 MB file takes 40 seconds at 100 Mbps rather than five; a slash 24 leaves 254 hosts and a slash 27 leaves 30; 3 GB takes 240 seconds; 5 000 000 bytes need 3 425 packets; a 20 ms round trip is 10 ms one way; 500 Mbps moves 3 750 MB a minute.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 questions |
| Suggested time | about 20 minutes |
| Difficulty mix | Foundation 2 · Intermediate 2 · Challenge 3 · Error redo 3 |
| Chapter | Chapter: S6 ICT | Networking and Data Transmission: Bandwidth, Subnets and Latency |
| Level | Error Retry |
02 Questions (10 items)
- FoundationError retry: a student read 100 Mbps as 100 MB per second and answered 5 seconds for a 500 MB file. What is the correct time?
- FoundationError retry: a student said a slash 24 network gives 256 usable hosts. What is the correct count?
- IntermediateError retry: a student said a slash 27 block of 32 addresses gives 32 usable hosts. What is correct?
- IntermediateError retry: a student treated megabits as megabytes and got 3 000 seconds for 3 GB at 100 Mbps. What is right, with 1 GB as 1 000 MB?
- ChallengeError retry: with a 1 500 byte MTU and 40 bytes of headers, a student divided 5 000 000 bytes by 1 500 and got 3 334 packets. What is correct?
- ChallengeError retry: a student took a 20 ms round trip time as the one way delay. What is the one way figure, and the total for eight round trips?
- ChallengeError retry: a student said a 500 Mbps link moves 500 MB a minute. How many megabytes really pass in a minute?
- Error redoError retry: a student cut a slash 24 into eight slash 27 blocks and counted 32 hosts each for 256. What is the true total?
- Error redoError retry: a student took 2 GB as 1 000 Mb and answered 40 seconds at 50 Mbps. What is correct?
- Error redoError retry: a student expected 600 Mbps for one TCP connection after bundling three 200 Mbps links. What is the single stream limit, and the time for 1 GB?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 40 seconds | 100 Mbps is 12.5 MB per second, and 500 MB over 12.5 gives 40 seconds, exactly eight times the wrong answer. |
| 2 | 254 hosts | Of the 256 addresses the first and last are the network and broadcast addresses, and neither can go to a host. |
| 3 | 30 hosts | Five host bits give 32 addresses, and removing the network and broadcast addresses leaves 30. |
| 4 | 240 seconds | Three gigabytes are 24 000 megabits, which over 100 Mbps is 240 seconds, 12.5 times faster than the wrong answer. |
| 5 | 3 425 packets | Each packet carries 1 460 bytes of data and 5 000 000 over 1 460 rounds up to 3 425, so the wrong answer is short by 91. |
| 6 | 10 ms one way and 160 ms for eight round trips | A round trip covers both directions, so halving gives the one way delay, and eight trips simply multiply 20 ms by eight. |
| 7 | 3 750 MB | 500 Mbps is 62.5 MB per second, and sixty seconds take it to 3 750 MB, or about 3.75 GB. |
| 8 | 240 hosts | Each block of 32 addresses keeps 30 after the two reserved ones, and eight blocks give 240. |
| 9 | 320 seconds | Two gigabytes are 16 000 megabits, and 16 000 over 50 gives 320 seconds, or about five minutes twenty. |
| 10 | Still 200 Mbps, so 40 seconds | Aggregation spreads separate connections, so one stream stays on one link, and 8 000 Mb over 200 Mbps is 40 seconds. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
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