CISA Practice Question: Information Systems Acquisition, Development, and Implementation
Which of the following is a key advantage of using an iterative SDLC model over a waterfall model?
⚠ Common exam trap
The trap is the option that sounds plausible but reverses the model's characteristic — candidates may pick 'reduces the need for user involvement' when iterative models actually demand more frequent user engagement than waterfall.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Provides more flexibility to adapt to changing requirements
Iterative SDLC models develop software in repeated cycles, delivering working increments and incorporating feedback between iterations, which allows requirements to evolve as understanding deepens. This built-in adaptability is the key advantage over waterfall, where requirements are frozen after the requirements phase and changes become expensive and disruptive. The iterative approach directly addresses the reality that requirements often change during long projects.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Reduces the need for user involvement
Why it's wrong here
Iterative models deliberately increase user involvement through repeated reviews and feedback after each increment. It is tempting because iterative delivery reduces the need for exhaustive upfront specification, but continuous stakeholder validation is central, not diminished, making this the opposite of the model's characteristic.
- ✗
Better suited for projects with stable requirements
Why it's wrong here
Stable requirements favour waterfall, where a single upfront specification suffices; iterative models absorb changing requirements across increments. It is tempting because iteration provides frequent checkpoints, but when requirements are fixed those cycles add overhead without corresponding benefit.
- ✗
Easier to manage project costs
Why it's wrong here
Iterative models typically increase cost volatility due to re-estimation after each cycle, whereas waterfall’s fixed upfront scope allows a single, stable budget baseline. This option is tempting because waterfall’s rigid phases often cause late-stage cost overruns, making iterative budgeting appear more predictable; in a project with highly stable requirements, waterfall would indeed offer tighter cost control.
- ✓
Provides more flexibility to adapt to changing requirements
Why this is correct
Iterative models deliver working increments in short cycles, allowing requirements to be revisited between iterations. Waterfall freezes requirements after the analysis phase, so late changes are costly; iteration directly satisfies the need to accommodate evolving requirements.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISACA exam blueprint
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