S4 ICT: Network Security And Data Protection (Paper 3 (challenge))

S4 ICT: Network Security and Data Protection (Paper 3 (challenge))

2026-11-14

Tutor Prep Guide · network security and data protection: password entropy and key spaces, phishing and social engineering, malware, firewall rules, symmetric and asymmetric encryption, hashing, two-factor authentication, 3-2-1 backup and quantified risk

S4 ICT: Network Security and Data Protection (Paper 3 (challenge))

Paper 3 (challenge): ten questions on network security and data protection, with answers and notes.

Direct answers　Level: S4 ICT; format: password space and entropy, phishing and social engineering, malware, firewall rules, encryption and hashing, 2FA, 3-2-1 backup.

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: Network Security and Data Protection
Level	S4

02　Questions (10 items)

FoundationHow many combinations does a ten-character password have if the set is lower-case letters plus digits, 36 characters?
FoundationWhat is the entropy of that 36-character-set, ten-position password?
FoundationA key space has 2 to the power of 56 values and an attacker tries a trillion keys per second. What is the average time in hours?
IntermediateAn asset is worth 50,000 dollars and one incident destroys 40 percent of it. What is the single loss expectancy?
IntermediateIf that incident happens twice a year, how much is saved after a 15,000 dollar annual control cost is deducted from the annualised loss expectancy?
IntermediateOf 1,200 staff, 8 percent click a phishing link and 25 percent of those give away a password. How many accounts are compromised, and what is the reset cost at 50 dollars each?
ChallengeForty staff each hold five separate system accounts for 200 in total. With role-based access control only 40 personal accounts plus 5 roles remain. What is the reduction?
ChallengeUploading 2 TB to a cloud backup at 80 MB/s takes about how many hours?
ChallengeFor a 256-bit key, how many keys must be tried on average, expressed as a power of two?
Error redoA student says a backup in another folder on the same computer is enough. What is wrong?

03　Answers and one-line notes

#	Answer	One-line note
1	3,656,158,440,062,976	36 to the power of 10 is 3,656,158,440,062,976, about 366 billion times a four-digit PIN.
2	About 52 bits	log2(36) is about 5.17, so ten positions give about 51.7 bits, between eight lower-case characters and twelve alphanumeric ones.
3	About 10 hours	On average only half the space is tried, 2 to the power of 55, which over 10 to the 12 is about 36,029 seconds, roughly 10 hours.
4	$20,000	50,000 times 0.4 is 20,000; single loss expectancy is asset value times exposure factor.
5	$25,000	The 40,000 annualised loss minus the 15,000 control leaves 25,000 saved, so the control pays for itself.
6	24 accounts, 1,200 dollars in total	1,200 times 0.08 is 96 clickers, times 0.25 is 24 compromised accounts, times 50 dollars is 1,200 dollars.
7	Down to 45 accounts, a 77.5 percent cut	(200 minus 45) over 200 is 77.5 percent, and least privilege also removes the orphan accounts left by leavers.
8	About 7.28 hours	2 times 1,024 times 1,024 is 2,097,152 MB, divided by 80 gives 26,214 seconds, about 7.28 hours.
9	2 to the power of 255	The full space is 2 to the 256 and half of it is 2 to the 255, far beyond reach in any practical time.
10	Wrong: ransomware and disk failure hit every folder on the same machine at once	A copy on the same machine is encrypted or destroyed together with the original, which is why 3-2-1 demands another medium plus an offsite or offline copy.

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.

For password strength, fix the character set then multiply by length, since each extra bit doubles the work; for phishing check the domain first, and after ransomware disconnect the network before restoring from an offline backup instead of guessing.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.