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S4 ICT: Computer Networks and Internet Protocols (Paper 2 (intermediate))
Tutor Prep Guide · LAN versus WAN, IPv4 and IPv6 address length, the 8-bit range of each octet, subnet masks and usable hosts, HTTP/HTTPS/FTP/SMTP with their ports, TCP versus UDP, and bandwidth to download time
S4 ICT: Computer Networks and Internet Protocols (Paper 2 (intermediate))
Paper 2 (intermediate): ten questions on networks and internet protocols, with answers and notes.
Direct answers Level: S4 ICT; format: IP addresses, subnet masks, usable hosts, ports, TCP and UDP, bandwidth arithmetic.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S4 ICT: Computer Networks and Internet Protocols |
| Level | S4 |
02 Questions (10 items)
- FoundationHow many seconds does a 500 MB file take at 200 Mbps?
- FoundationHow many seconds does a 4 GB (take it as 4 000 MB) video take at 50 Mbps?
- FoundationWhich of TCP and UDP confirms delivery and retransmits lost packets?
- IntermediateIn www.tutorzone.com.hk, what is the rightmost .hk part called?
- IntermediateWhat is the main job of DNS?
- IntermediateA connection uses port 443. Which service is it most likely to be?
- ChallengeHow many usable host addresses does a /26 subnet with mask 255.255.255.192 provide?
- ChallengeA subnet must hold 500 computers. What is the shortest prefix that still fits?
- ChallengeA link rated 1 Gbps delivers only 60% in practice. How many Mbps is that?
- Error redoA student claims UDP always delivers packets in the order they were sent. What is wrong?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 20 seconds | 500 MB times 8 is 4 000 Mb, and dividing by 200 Mbps gives 20 seconds. |
| 2 | 640 seconds | 4 000 MB times 8 is 32 000 Mb, and dividing by 50 Mbps gives 640 seconds, about ten and a half minutes. |
| 3 | TCP | TCP acknowledges, retransmits and preserves order; UDP just sends and does not guarantee delivery. |
| 4 | The top-level domain (country code) | The rightmost label is the top-level domain, and .hk is the Hong Kong country code; the labels to its left are lower levels and the host. |
| 5 | To translate a domain name into an IP address | Computers address each other by IP, so DNS translates the easy-to-remember domain name into the matching IP address. |
| 6 | HTTPS | Port 443 is the default for HTTPS, so the traffic is encrypted; plain HTTP would use 80. |
| 7 | 62 | A /26 leaves 6 host bits: 2 to the power 6 is 64, and minus 2 gives 62. |
| 8 | /23 (510 hosts) | A /24 holds only 254, which is not enough; a /23 gives 2 to the power 9, that is 512, minus 2 for 510. |
| 9 | 600 Mbps | 1 Gbps is 1 000 Mbps, and 60% of that is 600 Mbps. |
| 10 | UDP guarantees neither order nor delivery | UDP is connectionless: ordering and reliability must be handled by the application, which is its biggest difference from TCP. |
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.
First ask how many bits the address has and how many host bits remain, then decide between 2 to the power minus two and a plain subtraction; name both the protocol and its port, and convert MB to Mb before dividing by bandwidth.Tutor Registration →
Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.
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