SAA-C03 Design Cost-Optimized Architectures Practice Question
This SAA-C03 practice question tests your understanding of design cost-optimized architectures. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: dynamoDB on-demand charges per request for reads and writes.. 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.
A dev sandbox has unpredictable DynamoDB traffic with long idle periods and occasional spikes. Which capacity mode should minimize operational overhead and avoid paying for idle provisioned capacity? The architecture review board prefers a managed AWS-native control.
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
DynamoDB on-demand capacity mode
DynamoDB on-demand capacity mode (Option C) is ideal for unpredictable traffic with long idle periods and spikes because it automatically scales to handle workload demands without requiring any capacity planning. You pay only for the reads and writes you perform, eliminating the cost of idle provisioned capacity and the operational overhead of managing scaling thresholds.
Key principle: DynamoDB on-demand charges per request for reads and writes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Reserved capacity for maximum daily traffic
Why it's wrong here
Reserved capacity works best for predictable steady usage.
✗
Provisioned capacity set for peak traffic
Why it's wrong here
Provisioning for peak traffic wastes cost during idle periods.
✓
DynamoDB on-demand capacity mode
Why this is correct
On-demand capacity is suitable for unpredictable workloads and charges per request without capacity planning.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
DynamoDB on-demand charges per request for reads and writes.
✗
Global tables in every Region
Why it's wrong here
Global tables add replication cost and do not solve idle-capacity waste.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse 'Reserved capacity' (an EC2/RDS concept) with DynamoDB pricing, or assume Provisioned capacity is always cheaper without considering the cost of idle resources in unpredictable workloads.
Detailed technical explanation
How to think about this question
DynamoDB on-demand uses a per-request pricing model (per million read request units and write request units) and can handle up to 40,000 RCU/WCU per second per table without prior provisioning. However, it can cost significantly more than provisioned capacity for steady-state workloads, making it cost-optimal only for spiky or unpredictable traffic patterns. The service automatically scales throughput based on the request rate, but there is a soft limit of 40,000 units per second that can be increased via a Service Quota request.
KKey Concepts to Remember
DynamoDB on-demand charges per request for reads and writes.
On-demand mode automatically scales capacity to meet actual traffic.
No capacity planning or auto-scaling configuration is required with on-demand.
Ideal for unpredictable workloads with unknown traffic patterns.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
DynamoDB on-demand charges per request for reads and writes.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Review dynamoDB on-demand charges per request for reads and writes., then practise related SAA-C03 questions on the same topic to reinforce the concept.
Design Cost-Optimized Architectures — This question tests Design Cost-Optimized Architectures — DynamoDB on-demand charges per request for reads and writes..
What is the correct answer to this question?
The correct answer is: DynamoDB on-demand capacity mode — DynamoDB on-demand capacity mode (Option C) is ideal for unpredictable traffic with long idle periods and spikes because it automatically scales to handle workload demands without requiring any capacity planning. You pay only for the reads and writes you perform, eliminating the cost of idle provisioned capacity and the operational overhead of managing scaling thresholds.
What should I do if I get this SAA-C03 question wrong?
Review dynamoDB on-demand charges per request for reads and writes., then practise related SAA-C03 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
DynamoDB on-demand charges per request for reads and writes.
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