The correct action is to schedule the instance to automatically stop during off-hours and start before business hours. This directly reduces compute costs because stopped EC2 instances incur no running charges—only storage and EBS volume costs persist—so the company pays nothing for idle time between 5 PM and 9 AM. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of lifecycle management and cost optimization strategies for non-production environments, often appearing as a trap where candidates might mistakenly suggest resizing the instance or using a reserved instance instead. The key is recognizing that scheduled stop/start eliminates compute charges without losing data or configuration, and AWS Instance Scheduler or a simple Lambda function can enforce the routine reliably. Memory tip: think “stop the clock, not the instance”—stopping pauses billing for compute, while storage keeps ticking.
SOA-C02 Cost and Performance Optimization Practice Question
This SOA-C02 practice question tests your understanding of cost and performance optimization. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
A company runs a development Amazon EC2 instance that is only used during business hours (9 AM to 5 PM). The SysOps administrator wants to reduce compute costs. Which action should be taken?
Why wrong: On-Demand instances are flexible but more expensive than stopping the instance during idle periods.
B
Use a Reserved Instance
Why wrong: Reserved Instances are cost-effective for steady-state, 24/7 workloads, not for an instance that is only used 8 hours a day.
C
Schedule the instance to automatically stop during off-hours and start before business hours
This directly reduces costs by paying only for the hours the instance is running, aligning with the usage pattern.
D
Use a Spot instance
Why wrong: Spot instances offer lower cost but can be interrupted, which is unsuitable for a critical development environment that must be available during business hours.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Schedule the instance to automatically stop during off-hours and start before business hours
Option C is correct because the instance is only needed during business hours (9 AM to 5 PM), so automatically stopping it during off-hours and starting it before business hours eliminates compute charges for idle time. Stopped instances incur no EC2 instance running costs (only storage and EBS volume costs), directly reducing the compute bill. AWS Instance Scheduler or a simple cron-based Lambda function can enforce this schedule reliably.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use On-Demand instances
Why it's wrong here
On-Demand instances are flexible but more expensive than stopping the instance during idle periods.
✗
Use a Reserved Instance
Why it's wrong here
Reserved Instances are cost-effective for steady-state, 24/7 workloads, not for an instance that is only used 8 hours a day.
✓
Schedule the instance to automatically stop during off-hours and start before business hours
Why this is correct
This directly reduces costs by paying only for the hours the instance is running, aligning with the usage pattern.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a Spot instance
Why it's wrong here
Spot instances offer lower cost but can be interrupted, which is unsuitable for a critical development environment that must be available during business hours.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse cost reduction strategies and choose Reserved Instances (Option B) for any recurring workload, failing to recognize that a development instance with limited daily usage does not justify a long-term commitment and that stopping the instance when idle is the most direct way to eliminate compute costs.
Detailed technical explanation
How to think about this question
Under the hood, stopping an EC2 instance releases the underlying physical hardware and frees the compute resources, so you are only billed for attached EBS volumes (storage) and Elastic IP addresses if allocated. Starting the instance re-provisions a new host, which may take a few minutes but ensures no compute cost during the stopped period. This approach is commonly implemented using AWS Instance Scheduler, which uses CloudWatch Events and Lambda to stop/start instances based on a defined schedule, or via a simple cron job on the instance itself.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Cost and Performance Optimization — This question tests Cost and Performance Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Schedule the instance to automatically stop during off-hours and start before business hours — Option C is correct because the instance is only needed during business hours (9 AM to 5 PM), so automatically stopping it during off-hours and starting it before business hours eliminates compute charges for idle time. Stopped instances incur no EC2 instance running costs (only storage and EBS volume costs), directly reducing the compute bill. AWS Instance Scheduler or a simple cron-based Lambda function can enforce this schedule reliably.
What should I do if I get this SOA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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