Quick Answer
The answer is developing data flow diagrams and defining system architecture, as both are key activities in the system design phase of the SDLC. Defining system architecture establishes the high-level structure of the system, including hardware, software, and network components, creating a blueprint that guides detailed design and ensures alignment with functional and non-functional requirements. Developing data flow diagrams, meanwhile, models how data moves through the system, clarifying processes and data stores for implementation. On the Certified Information Systems Auditor CISA exam, this question tests your ability to distinguish design-phase tasks from requirements-gathering or testing activities—a common trap is confusing data flow diagrams with requirements documentation or mistaking architecture definition for a planning-phase task. A useful memory tip is to think of the design phase as the bridge between “what” (requirements) and “how” (implementation), where you structure the system and map its data flows.
This CISA practice question tests your understanding of information systems acquisition, development and implementation. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO of the following are key activities in the system design phase of the SDLC?
Defining system architecture
A design activity.
Writing unit tests
Why wrong: Coding phase.
Performing user acceptance testing
Why wrong: Testing phase.
Developing data flow diagrams
A design activity.
Gathering business requirements
Why wrong: Requirements phase.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Defining system architecture
Defining system architecture is a key activity in the system design phase because it establishes the high-level structure of the system, including hardware, software, network components, and their interactions. This blueprint guides subsequent detailed design and implementation, ensuring alignment with functional and non-functional requirements. Without a defined architecture, the system risks integration failures and scalability issues.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Defining system architecture
Why this is correct
A design activity.
Related concept
Read the scenario before looking for a memorised answer.
Writing unit tests
Why it's wrong here
Coding phase.
Performing user acceptance testing
Why it's wrong here
Testing phase.
Developing data flow diagrams
Why this is correct
A design activity.
Related concept
Read the scenario before looking for a memorised answer.
Gathering business requirements
Why it's wrong here
Requirements phase.
Common exam traps
The trap here is that candidates often confuse the system design phase with later phases like testing or earlier phases like requirements gathering, leading them to select activities such as writing unit tests or gathering business requirements as design-phase tasks.
Detailed technical explanation
Developing data flow diagrams (DFDs) during system design helps visualize how data moves through the system, identifying processes, data stores, and external entities. DFDs use standardized notations like Gane-Sarson or Yourdon-DeMarco, and they are critical for ensuring data integrity and security controls are embedded in the design. In real-world scenarios, DFDs expose potential bottlenecks or unauthorized data access paths, enabling architects to refine the design before coding begins.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the CISA exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Information Systems Acquisition, Development and Implementation — This question tests Information Systems Acquisition, Development and Implementation — Read the scenario before looking for a memorised answer..
The correct answer is: Defining system architecture — Defining system architecture is a key activity in the system design phase because it establishes the high-level structure of the system, including hardware, software, network components, and their interactions. This blueprint guides subsequent detailed design and implementation, ensuring alignment with functional and non-functional requirements. Without a defined architecture, the system risks integration failures and scalability issues.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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