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Worked solutions

IB Computer Science SL · Paper 1

Computer Science, Standard Level

Session: May 2017
Marks: 70
Duration: 1 hour 30 min
Calculator: Not allowed
Questions: 13

Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q11 Q12 Q13

Keep your copy of the paper open alongside. We don't reproduce the questions: each part below is labelled to match the May 2017 global paper, which your school or the IB can provide.

Practice mode

Hide our working until you've had a go.

Questions 1–10 · 25 marks

Question 1

2 marks

Use of beta testing

System fundamentals

(a)

2 marks

Define beta testing in the software deployment lifecycle:
Beta testing involves releasing a pre-release version of software to an external audience of target users or the public prior to final distribution.
Users operate the software in real-world environments to uncover unforeseen defects and provide practical feedback for refinements.

Mentor tip

Clarify that testing is conducted by real users outside the development team before the formal public release.

Question 2

2 marks

Causes of data loss

System fundamentals

(a)

2 marks

Identify two distinct causes of data loss:
1) Physical disasters or hardware malfunctions, such as power outages or hard drive head crashes.
2) Human error or security compromises, such as accidental deletion or malicious ransomware infections.

Mentor tip

Select two fundamentally different causes, such as a hardware malfunction and user error.

Question 3

2 marks

Reasons for releasing a software update

System fundamentals

(a)

2 marks

Identify two main drivers for distributing software updates:
1) Fixing security vulnerabilities and software bugs discovered after release.
2) Adding new functionality or maintaining compatibility with evolving operating systems and hardware platforms.

Mentor tip

Focus on bug/security patches and feature or compatibility improvements.

Question 4

2 marks

Cache memory and processor performance

Computer organisation

(a)

2 marks

Explain why cache memory speeds up computer processing:
Cache memory is built from high-speed static RAM (SRAM) positioned physically closer to the processor cores than primary memory (DRAM).
It holds frequently accessed instructions and data, reducing processor latency by avoiding slower bus fetches across the system bus.

Mentor tip

Highlight higher access speeds and the principle of locality for frequently requested instructions.

Question 5

2 marks

Operating system memory management and stability

Resource management

(a)

2 marks

Describe how memory management prevents system crashes during concurrent execution:
The operating system isolates and allocates discrete, bounded address spaces to each executing process.
Memory protection mechanisms ensure that no process can read or overwrite the memory allocated to another program or the operating system kernel.

Mentor tip

Emphasize memory allocation and memory protection barriers that stop processes from overwriting one another.

Question 6

2 marks

OSI model layers

Networks

(a)

2 marks

Identify two layers from the standard 7-layer OSI model:
1) Network layer (handles logical addressing and routing of packets across networks).
2) Transport layer (manages end-to-end communication, segmentation, and reliability).

Mentor tip

Any valid layers from Physical, Data Link, Network, Transport, Session, Presentation, or Application satisfy the prompt.

Question 7

3 marks

Potential negative consequences of data compression

Networks

(a)

3 marks

Explain the drawbacks and risks associated with data compression:
1) Lossy compression permanently discards data points, causing irreversible loss of detail in media files like images, video, or audio.
2) If the original uncompressed source file is lost or overwritten, the removed data cannot be reconstructed upon decompression.
3) Decompressing compressed archives requires processing overhead, and file corruption in compressed archives can render entire datasets unreadable.

Mentor tip

Highlight the irreversibility of lossy compression and degradation of fidelity.

Question 8

3 marks

MAC address filtering and network security

Networks

(a)

3 marks

Explain how Media Access Control (MAC) addresses enhance security:
1) Every network interface card (NIC) possesses a globally unique hardware MAC address assigned at manufacturing.
2) A network switch or wireless access point can enforce a whitelist of authorized MAC addresses, rejecting connection requests from unlisted devices.
3) This adds an extra layer of access verification, restricting network entry even if an unauthorized user acquires standard network credentials.

Mentor tip

Note how unique hardware identifiers are checked against an approved whitelist before network access is granted.

Question 9

3 marks

Steps in a selection sort

Computational thinking, problem-solving and programming

(a)

3 marks

Outline the algorithmic steps of a selection sort:
1) Scan the unsorted portion of the list to locate the minimum (or maximum) element.
2) Swap the identified minimum element with the element at the beginning of the unsorted section (placing it into its permanent sorted position).
3) Advance the boundary of the sorted subarray by one position and repeat the scan across the remaining unsorted elements until the list is completely ordered.

O (n^{2}) comparisons across n - 1 passes

Mentor tip

Explain finding the minimum element in the unsorted section and swapping it into the sorted section.

Question 10

4 marks

Differences between high-level programming languages

Computational thinking, problem-solving and programming

(a)

4 marks

Outline two ways high-level programming languages differ beyond vocabulary/keywords:
1) Translation method: Some languages compile directly into native machine code (e.g., C++), whereas others interpret source code line by line or compile to intermediate bytecode executed on a virtual machine (e.g., Java, Python).
2) Programming paradigm: Languages follow different design paradigms, such as object-oriented programming (emphasizing classes and encapsulation), procedural programming (emphasizing sequential subroutines), or functional programming (emphasizing pure functions and immutable state).

Mentor tip

Select translation methodology (compiled vs interpreted) and programming paradigms (OOP vs procedural).

Questions 11–13 · 45 marks

Question 11

15 marks

Corporate takeover, data migration, and logic circuits

System fundamentals
Computer organisation

(a)

5 marks

Define data migration:
The process of transferring data between storage types, formats, or computer systems, specifically from an acquired firm's databases to the acquiring company's platform.
Describe two problems that must be overcome during data migration:
1) Data format and structural incompatibility: Differing data schemas, table relationships, or field lengths require complex ETL transformations, risking truncated or misaligned records.
2) Incompatible validation rules or character encodings: Inconsistent validation checks can reject valid legacy entries, while differing encodings can corrupt text characters during transfer.

Mentor tip

Provide the formal transfer definition followed by two distinct technical issues such as structural divergence and schema validation mismatches.

(b)

4 marks

Describe two aspects of change management arising from the takeover:
1) Workforce training and restructuring: Existing staff must be retrained on merged systems and workflows, while managing employee concerns regarding role redundancy.
2) System changeover strategy and testing: Planning the rollout method (e.g., phased transition or parallel running) alongside exhaustive testing of combined infrastructure to prevent operational disruption.

Mentor tip

Address human/workforce considerations alongside transition strategy and testing.

(c)

4 marks

Analyze the given logic circuit with inputs A and B:
Intermediate gate X computes \( X = \text{NAND}(A, B) = \overline{A \cdot B} \).
Intermediate gate Y computes \( Y = \text{OR}(A, B) = A + B \).
Final gate computes \( C = \text{AND}(X, Y) = (\overline{A \cdot B}) \cdot (A + B) \).
Construct the complete truth table:
Row 1: A = 0, B = 0 -> X = 1, Y = 0 -> C = 0.
Row 2: A = 0, B = 1 -> X = 1, Y = 1 -> C = 1.
Row 3: A = 1, B = 0 -> X = 1, Y = 1 -> C = 1.
Row 4: A = 1, B = 1 -> X = 0, Y = 1 -> C = 0.
Identify the equivalent single logic gate:
The output C produces 1 when inputs differ and 0 when identical, which is an XOR gate (exclusive OR).

C = \overline{A \cdot B} \cdot (A + B) = (\overline{A} + \overline{B}) \cdot (A + B) = A \oplus B

Mentor tip

Notice that (NOT(A AND B)) AND (A OR B) is the standard definition of the XOR function.

(d)

2 marks

Outline how truth tables verify equivalence between two logic diagrams:
1) Enumerate all possible combinations of binary inputs across both circuits.
2) Compare the resulting output values row by row; if the outputs match identically for every input permutation, the circuits are functionally equivalent.

Mentor tip

Confirm that identical outputs across every matching input row establish formal logic equivalence.

Question 12

15 marks

Tracing collections and array search algorithms

Computational thinking, problem-solving and programming

(a)

3 marks

Trace the collection loop step by step for DATA = {2, 4, -1, 3}:
Iteration 1: hasNext() is true; A = 2. Since 2 >= 0 is true and 2 mod 2 = 0 is true, 2 is added to collection B. Contents of B: {2}. Contents of C: {}.
Iteration 2: hasNext() is true; A = 4. Since 4 >= 0 is true and 4 mod 2 = 0 is true, 4 is added to collection B. Contents of B: {2, 4}. Contents of C: {}.
Iteration 3: hasNext() is true; A = -1. Since -1 >= 0 is false, the inner conditions are skipped. Contents of B: {2, 4}. Contents of C: {}.
Iteration 4: hasNext() is true; A = 3. Since 3 >= 0 is true and 3 mod 2 = 0 is false, 3 is added to collection C. Contents of B: {2, 4}. Contents of C: {3}.
Iteration 5: hasNext() is false; loop terminates.
Final results: Collection B contains {2, 4}; Collection C contains {3}.

Mentor tip

Verify that negative numbers bypass both branches, leaving collections unchanged.

(b)

4 marks

Outline the algorithmic steps for a binary search on an ordered array:
1) Calculate the midpoint index: MID = (LOW + HI) div 2.
2) Compare the target value with ARRAY[MID]. If ARRAY[MID] equals the search value, terminate the search successfully.
3) If the search value is less than ARRAY[MID], narrow the search space to the lower half by updating HI = MID - 1.
4) If the search value is greater than ARRAY[MID], narrow the search space to the upper half by updating LOW = MID + 1.
5) Repeat this halving procedure until the target element is located.

MID = ⌊(LOW + HI) /2 ⌋

Mentor tip

State clearly how the midpoint is calculated and how HI or LOW is shifted on each comparison.

(c)

5 marks

Construct pseudocode to input S, transfer elements from collection NUMBERS into array D, perform a linear search, and output the result:
input S
COUNT = 0
loop while NUMBERS.hasNext()
D[COUNT] = NUMBERS.getNext()
COUNT = COUNT + 1
end loop
FOUND = false
INDEX = 0
loop while (INDEX < COUNT) AND (NOT FOUND)
if D[INDEX] = S then
FOUND = true
end if
INDEX = INDEX + 1
end loop
if FOUND then
output "found"
else
output "not found"
end if

Mentor tip

Transfer items with a counting index, then run a standard linear search with a boolean flag.

(d)

3 marks

Suggest how to verify ascending order while populating array D without pseudocode:
1) Initialize a boolean flag (e.g., IS_SORTED) to true.
2) Beginning with the second item inserted into array D (at index 1), compare the newly placed element with the element immediately preceding it (D[COUNT - 1]).
3) If any current element is less than the previous element, toggle the flag to false. If the flag remains true once all elements are read, array D is confirmed to be in ascending order.

Mentor tip

Use a boolean order flag and compare each incoming element from index 1 against its predecessor.

Question 13

15 marks

Network communication, packet switching, and public Wi-Fi

Networks

(a)

5 marks

Identify two network types combined across the internet for secure corporate communication:
1) Wide Area Network (WAN) / Global Area Network (GAN) connecting remote corporate offices.
2) Virtual Private Network (VPN) enabling remote sales agents to securely tunnel into the corporate intranet.
Describe security characteristics specific to a VPN:
1) Tunneling: Data packets are encapsulated within external transit packets.
2) End-to-end encryption: Payloads are encrypted so intercepted packets cannot be deciphered.
3) Identity masking: The user's actual IP address and location are obscured from outside observers.

Mentor tip

Identify WAN and VPN, then detail tunneling, encryption, and IP masking.

(b)

6 marks

Discuss the importance of protocols in packet switching:
1) Definition and role: Protocols provide standardized communication rules governing packet construction, transmission, and disassembly.
2) Packet formatting: Protocols specify identical headers (containing source address, destination address, and sequence number) and trailers (checksums for error detection).
3) Decoding and integrity: Standard packet headers allow routers to inspect addresses and route packets dynamically across independent paths.
4) Reassembly: Sequence numbers ensure that packets arriving out of order or via different paths can be reconstructed into the complete original message.

Mentor tip

Cover packet formatting, independent router forwarding via destination headers, sequence numbers, and error checking.

(c)

4 marks

Describe two advantages to society of widespread public Wi-Fi availability:
1) Flexible mobile productivity: Employees and students can work, access cloud documents, and collaborate in public venues (such as cafes, libraries, and transit stations) without physical office constraints.
2) Economic savings and digital inclusion: Public Wi-Fi offers internet connectivity without consuming expensive mobile cellular data allowances, providing equitable access to online services and information.

Mentor tip

Choose two distinct societal benefits, such as remote work flexibility and mobile data cost savings.

Our analysis

Where the marks are

Each part sorted by the topic it mostly tests. Networks carries the most marks on this paper.

Networks23 marks · 33%
Q6, Q7, Q8, Q13
Computational thinking, problem-solving and programming22 marks · 31%
Q9, Q10, Q12
System fundamentals15 marks · 21%
Q1, Q2, Q3, Q11
Computer organisation8 marks · 11%
Q4, Q11
Resource management2 marks · 3%
Q5

Mentor insights

Traps to watch for

01
Selection sort inner loop versus bubble sort · Q9
Selection sort scans the unsorted segment to find the minimum index and performs at most one swap per outer pass, whereas bubble sort compares and swaps adjacent out-of-order pairs repeatedly.
02
Intermediate signals in compound logic diagrams · Q11
Carefully trace intermediate signals X = NAND(A, B) and Y = OR(A, B). When A = 1 and B = 1, X = 0 and Y = 1, giving final output C = 0.
03
Packet switching versus circuit switching mechanisms · Q13
In packet switching, packets travel dynamically along independent network routes rather than over a dedicated physical path. Sequence numbers in the header are required to reassemble out-of-order packets at the receiver.

Solutions and tips are GeorgeTheTutor's own; the questions are not reproduced here. Not affiliated with or endorsed by the International Baccalaureate Organization.

Want someone to go through your paper with you?

Our maths mentors took these exams recently. One-to-one, they'll find where your marks are going and fix it before May.

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Worked solutions

IB Computer Science SL · Paper 1

Computer Science, Standard Level

Session: May 2017
Marks: 70
Duration: 1 hour 30 min
Calculator: Not allowed
Questions: 13

Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q11 Q12 Q13

Keep your copy of the paper open alongside. We don't reproduce the questions: each part below is labelled to match the May 2017 global paper, which your school or the IB can provide.

Practice mode

Hide our working until you've had a go.

Questions 1–10 · 25 marks

Question 1

2 marks

Use of beta testing

System fundamentals

(a)

2 marks

Define beta testing in the software deployment lifecycle:
Beta testing involves releasing a pre-release version of software to an external audience of target users or the public prior to final distribution.
Users operate the software in real-world environments to uncover unforeseen defects and provide practical feedback for refinements.

Mentor tip

Clarify that testing is conducted by real users outside the development team before the formal public release.

Question 2

2 marks

Causes of data loss

System fundamentals

(a)

2 marks

Identify two distinct causes of data loss:
1) Physical disasters or hardware malfunctions, such as power outages or hard drive head crashes.
2) Human error or security compromises, such as accidental deletion or malicious ransomware infections.

Mentor tip

Select two fundamentally different causes, such as a hardware malfunction and user error.

Question 3

2 marks

Reasons for releasing a software update

System fundamentals

(a)

2 marks

Identify two main drivers for distributing software updates:
1) Fixing security vulnerabilities and software bugs discovered after release.
2) Adding new functionality or maintaining compatibility with evolving operating systems and hardware platforms.

Mentor tip

Focus on bug/security patches and feature or compatibility improvements.

Question 4

2 marks

Cache memory and processor performance

Computer organisation

(a)

2 marks

Explain why cache memory speeds up computer processing:
Cache memory is built from high-speed static RAM (SRAM) positioned physically closer to the processor cores than primary memory (DRAM).
It holds frequently accessed instructions and data, reducing processor latency by avoiding slower bus fetches across the system bus.

Mentor tip

Highlight higher access speeds and the principle of locality for frequently requested instructions.

Question 5

2 marks

Operating system memory management and stability

Resource management

(a)

2 marks

Describe how memory management prevents system crashes during concurrent execution:
The operating system isolates and allocates discrete, bounded address spaces to each executing process.
Memory protection mechanisms ensure that no process can read or overwrite the memory allocated to another program or the operating system kernel.

Mentor tip

Emphasize memory allocation and memory protection barriers that stop processes from overwriting one another.

Question 6

2 marks

OSI model layers

Networks

(a)

2 marks

Identify two layers from the standard 7-layer OSI model:
1) Network layer (handles logical addressing and routing of packets across networks).
2) Transport layer (manages end-to-end communication, segmentation, and reliability).

Mentor tip

Any valid layers from Physical, Data Link, Network, Transport, Session, Presentation, or Application satisfy the prompt.

Question 7

3 marks

Potential negative consequences of data compression

Networks

(a)

3 marks

Explain the drawbacks and risks associated with data compression:
1) Lossy compression permanently discards data points, causing irreversible loss of detail in media files like images, video, or audio.
2) If the original uncompressed source file is lost or overwritten, the removed data cannot be reconstructed upon decompression.
3) Decompressing compressed archives requires processing overhead, and file corruption in compressed archives can render entire datasets unreadable.

Mentor tip

Highlight the irreversibility of lossy compression and degradation of fidelity.

Question 8

3 marks

MAC address filtering and network security

Networks

(a)

3 marks

Explain how Media Access Control (MAC) addresses enhance security:
1) Every network interface card (NIC) possesses a globally unique hardware MAC address assigned at manufacturing.
2) A network switch or wireless access point can enforce a whitelist of authorized MAC addresses, rejecting connection requests from unlisted devices.
3) This adds an extra layer of access verification, restricting network entry even if an unauthorized user acquires standard network credentials.

Mentor tip

Note how unique hardware identifiers are checked against an approved whitelist before network access is granted.

Question 9

3 marks

Steps in a selection sort

Computational thinking, problem-solving and programming

(a)

3 marks

Outline the algorithmic steps of a selection sort:
1) Scan the unsorted portion of the list to locate the minimum (or maximum) element.
2) Swap the identified minimum element with the element at the beginning of the unsorted section (placing it into its permanent sorted position).
3) Advance the boundary of the sorted subarray by one position and repeat the scan across the remaining unsorted elements until the list is completely ordered.

O (n^{2}) comparisons across n - 1 passes

Mentor tip

Explain finding the minimum element in the unsorted section and swapping it into the sorted section.

Question 10

4 marks

Differences between high-level programming languages

Computational thinking, problem-solving and programming

(a)

4 marks

Outline two ways high-level programming languages differ beyond vocabulary/keywords:
1) Translation method: Some languages compile directly into native machine code (e.g., C++), whereas others interpret source code line by line or compile to intermediate bytecode executed on a virtual machine (e.g., Java, Python).
2) Programming paradigm: Languages follow different design paradigms, such as object-oriented programming (emphasizing classes and encapsulation), procedural programming (emphasizing sequential subroutines), or functional programming (emphasizing pure functions and immutable state).

Mentor tip

Select translation methodology (compiled vs interpreted) and programming paradigms (OOP vs procedural).

Questions 11–13 · 45 marks

Question 11

15 marks

Corporate takeover, data migration, and logic circuits

System fundamentals
Computer organisation

(a)

5 marks

Define data migration:
The process of transferring data between storage types, formats, or computer systems, specifically from an acquired firm's databases to the acquiring company's platform.
Describe two problems that must be overcome during data migration:
1) Data format and structural incompatibility: Differing data schemas, table relationships, or field lengths require complex ETL transformations, risking truncated or misaligned records.
2) Incompatible validation rules or character encodings: Inconsistent validation checks can reject valid legacy entries, while differing encodings can corrupt text characters during transfer.

Mentor tip

Provide the formal transfer definition followed by two distinct technical issues such as structural divergence and schema validation mismatches.

(b)

4 marks

Describe two aspects of change management arising from the takeover:
1) Workforce training and restructuring: Existing staff must be retrained on merged systems and workflows, while managing employee concerns regarding role redundancy.
2) System changeover strategy and testing: Planning the rollout method (e.g., phased transition or parallel running) alongside exhaustive testing of combined infrastructure to prevent operational disruption.

Mentor tip

Address human/workforce considerations alongside transition strategy and testing.

(c)

4 marks

Analyze the given logic circuit with inputs A and B:
Intermediate gate X computes \( X = \text{NAND}(A, B) = \overline{A \cdot B} \).
Intermediate gate Y computes \( Y = \text{OR}(A, B) = A + B \).
Final gate computes \( C = \text{AND}(X, Y) = (\overline{A \cdot B}) \cdot (A + B) \).
Construct the complete truth table:
Row 1: A = 0, B = 0 -> X = 1, Y = 0 -> C = 0.
Row 2: A = 0, B = 1 -> X = 1, Y = 1 -> C = 1.
Row 3: A = 1, B = 0 -> X = 1, Y = 1 -> C = 1.
Row 4: A = 1, B = 1 -> X = 0, Y = 1 -> C = 0.
Identify the equivalent single logic gate:
The output C produces 1 when inputs differ and 0 when identical, which is an XOR gate (exclusive OR).

C = \overline{A \cdot B} \cdot (A + B) = (\overline{A} + \overline{B}) \cdot (A + B) = A \oplus B

Mentor tip

Notice that (NOT(A AND B)) AND (A OR B) is the standard definition of the XOR function.

(d)

2 marks

Outline how truth tables verify equivalence between two logic diagrams:
1) Enumerate all possible combinations of binary inputs across both circuits.
2) Compare the resulting output values row by row; if the outputs match identically for every input permutation, the circuits are functionally equivalent.

Mentor tip

Confirm that identical outputs across every matching input row establish formal logic equivalence.

Question 12

15 marks

Tracing collections and array search algorithms

Computational thinking, problem-solving and programming

(a)

3 marks

Trace the collection loop step by step for DATA = {2, 4, -1, 3}:
Iteration 1: hasNext() is true; A = 2. Since 2 >= 0 is true and 2 mod 2 = 0 is true, 2 is added to collection B. Contents of B: {2}. Contents of C: {}.
Iteration 2: hasNext() is true; A = 4. Since 4 >= 0 is true and 4 mod 2 = 0 is true, 4 is added to collection B. Contents of B: {2, 4}. Contents of C: {}.
Iteration 3: hasNext() is true; A = -1. Since -1 >= 0 is false, the inner conditions are skipped. Contents of B: {2, 4}. Contents of C: {}.
Iteration 4: hasNext() is true; A = 3. Since 3 >= 0 is true and 3 mod 2 = 0 is false, 3 is added to collection C. Contents of B: {2, 4}. Contents of C: {3}.
Iteration 5: hasNext() is false; loop terminates.
Final results: Collection B contains {2, 4}; Collection C contains {3}.

Mentor tip

Verify that negative numbers bypass both branches, leaving collections unchanged.

(b)

4 marks

Outline the algorithmic steps for a binary search on an ordered array:
1) Calculate the midpoint index: MID = (LOW + HI) div 2.
2) Compare the target value with ARRAY[MID]. If ARRAY[MID] equals the search value, terminate the search successfully.
3) If the search value is less than ARRAY[MID], narrow the search space to the lower half by updating HI = MID - 1.
4) If the search value is greater than ARRAY[MID], narrow the search space to the upper half by updating LOW = MID + 1.
5) Repeat this halving procedure until the target element is located.

MID = ⌊(LOW + HI) /2 ⌋

Mentor tip

State clearly how the midpoint is calculated and how HI or LOW is shifted on each comparison.

(c)

5 marks

Construct pseudocode to input S, transfer elements from collection NUMBERS into array D, perform a linear search, and output the result:
input S
COUNT = 0
loop while NUMBERS.hasNext()
D[COUNT] = NUMBERS.getNext()
COUNT = COUNT + 1
end loop
FOUND = false
INDEX = 0
loop while (INDEX < COUNT) AND (NOT FOUND)
if D[INDEX] = S then
FOUND = true
end if
INDEX = INDEX + 1
end loop
if FOUND then
output "found"
else
output "not found"
end if

Mentor tip

Transfer items with a counting index, then run a standard linear search with a boolean flag.

(d)

3 marks

Suggest how to verify ascending order while populating array D without pseudocode:
1) Initialize a boolean flag (e.g., IS_SORTED) to true.
2) Beginning with the second item inserted into array D (at index 1), compare the newly placed element with the element immediately preceding it (D[COUNT - 1]).
3) If any current element is less than the previous element, toggle the flag to false. If the flag remains true once all elements are read, array D is confirmed to be in ascending order.

Mentor tip

Use a boolean order flag and compare each incoming element from index 1 against its predecessor.

Question 13

15 marks

Network communication, packet switching, and public Wi-Fi

Networks

(a)

5 marks

Identify two network types combined across the internet for secure corporate communication:
1) Wide Area Network (WAN) / Global Area Network (GAN) connecting remote corporate offices.
2) Virtual Private Network (VPN) enabling remote sales agents to securely tunnel into the corporate intranet.
Describe security characteristics specific to a VPN:
1) Tunneling: Data packets are encapsulated within external transit packets.
2) End-to-end encryption: Payloads are encrypted so intercepted packets cannot be deciphered.
3) Identity masking: The user's actual IP address and location are obscured from outside observers.

Mentor tip

Identify WAN and VPN, then detail tunneling, encryption, and IP masking.

(b)

6 marks

Discuss the importance of protocols in packet switching:
1) Definition and role: Protocols provide standardized communication rules governing packet construction, transmission, and disassembly.
2) Packet formatting: Protocols specify identical headers (containing source address, destination address, and sequence number) and trailers (checksums for error detection).
3) Decoding and integrity: Standard packet headers allow routers to inspect addresses and route packets dynamically across independent paths.
4) Reassembly: Sequence numbers ensure that packets arriving out of order or via different paths can be reconstructed into the complete original message.

Mentor tip

Cover packet formatting, independent router forwarding via destination headers, sequence numbers, and error checking.

(c)

4 marks

Describe two advantages to society of widespread public Wi-Fi availability:
1) Flexible mobile productivity: Employees and students can work, access cloud documents, and collaborate in public venues (such as cafes, libraries, and transit stations) without physical office constraints.
2) Economic savings and digital inclusion: Public Wi-Fi offers internet connectivity without consuming expensive mobile cellular data allowances, providing equitable access to online services and information.

Mentor tip

Choose two distinct societal benefits, such as remote work flexibility and mobile data cost savings.

Our analysis

Where the marks are

Each part sorted by the topic it mostly tests. Networks carries the most marks on this paper.

Networks23 marks · 33%
Q6, Q7, Q8, Q13
Computational thinking, problem-solving and programming22 marks · 31%
Q9, Q10, Q12
System fundamentals15 marks · 21%
Q1, Q2, Q3, Q11
Computer organisation8 marks · 11%
Q4, Q11
Resource management2 marks · 3%
Q5

Mentor insights

Traps to watch for

01
Selection sort inner loop versus bubble sort · Q9
Selection sort scans the unsorted segment to find the minimum index and performs at most one swap per outer pass, whereas bubble sort compares and swaps adjacent out-of-order pairs repeatedly.
02
Intermediate signals in compound logic diagrams · Q11
Carefully trace intermediate signals X = NAND(A, B) and Y = OR(A, B). When A = 1 and B = 1, X = 0 and Y = 1, giving final output C = 0.
03
Packet switching versus circuit switching mechanisms · Q13
In packet switching, packets travel dynamically along independent network routes rather than over a dedicated physical path. Sequence numbers in the header are required to reassemble out-of-order packets at the receiver.

Solutions and tips are GeorgeTheTutor's own; the questions are not reproduced here. Not affiliated with or endorsed by the International Baccalaureate Organization.

Want someone to go through your paper with you?

Our maths mentors took these exams recently. One-to-one, they'll find where your marks are going and fix it before May.

Find your maths mentor More past papers