The answer is to use AWS Instance Scheduler to stop and start the RDS instance on a schedule. This is the most cost-effective solution because it is a fully managed, native AWS service that automatically stops the DB instance outside of business hours—eliminating compute costs while retaining storage and configuration—and starts it again at 9 AM on weekdays, directly addressing the need to schedule RDS start and stop for cost optimization in a development environment. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of lifecycle management and cost control for RDS, often contrasting Instance Scheduler against manual actions or less efficient options like modifying the instance type. A common trap is to consider stopping the instance via a Lambda function or a simple CloudWatch alarm, but Instance Scheduler is purpose-built for recurring schedules and requires no custom code. Remember the memory tip: “Scheduler saves schedule stress”—when you see a recurring start/stop need, think Instance Scheduler first.
SOA-C02 Cost and Performance Optimization Practice Question
This SOA-C02 practice question tests your understanding of cost and performance optimization. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 SysOps administrator needs to reduce costs for an Amazon RDS for MySQL DB instance that is used for development. The instance is only needed during business hours (9 AM to 5 PM) on weekdays. Which solution is the MOST cost-effective while maintaining the ability to start and stop the instance on a schedule?
Why wrong: Read replica does not reduce costs; it adds cost.
B
Purchase a reserved instance for the DB instance.
Why wrong: Reserved instances require a 1- or 3-year commitment, not suitable for partial usage.
C
Use a Lambda function to stop the instance at 5 PM and start it at 9 AM on weekdays.
Why wrong: Stopping instance reduces compute cost, but storage costs remain. However, it is cost-effective, but Lambda alone cannot schedule without additional services like CloudWatch Events.
D
Use AWS Instance Scheduler to stop and start the RDS instance on a schedule.
Instance Scheduler automates stop/start, reducing compute costs during non-business hours.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use AWS Instance Scheduler to stop and start the RDS instance on a schedule.
Option D is correct because AWS Instance Scheduler is a fully managed solution designed specifically to start and stop RDS instances on a defined schedule, such as weekdays from 9 AM to 5 PM. This eliminates compute costs during non-business hours while preserving the instance's storage and configuration, making it the most cost-effective and reliable approach for a development environment.
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.
✗
Create a read replica and promote it when needed.
Why it's wrong here
Read replica does not reduce costs; it adds cost.
✗
Purchase a reserved instance for the DB instance.
Why it's wrong here
Reserved instances require a 1- or 3-year commitment, not suitable for partial usage.
✗
Use a Lambda function to stop the instance at 5 PM and start it at 9 AM on weekdays.
Why it's wrong here
Stopping instance reduces compute cost, but storage costs remain. However, it is cost-effective, but Lambda alone cannot schedule without additional services like CloudWatch Events.
✓
Use AWS Instance Scheduler to stop and start the RDS instance on a schedule.
Why this is correct
Instance Scheduler automates stop/start, reducing compute costs during non-business hours.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose a Lambda function (Option C) thinking it is the most flexible, but they overlook that AWS Instance Scheduler is a pre-built, managed solution that reduces operational overhead and is the recommended pattern for scheduled start/stop of RDS instances in the AWS Well-Architected Framework.
Detailed technical explanation
How to think about this question
AWS Instance Scheduler uses a CloudFormation template to deploy a DynamoDB table for storing schedules, a Lambda function for execution, and Amazon EventBridge rules for triggering. It supports RDS, EC2, and Auto Scaling groups, and can handle timezone-aware schedules with custom periods. Under the hood, the Lambda function calls the RDS StopDBInstance and StartDBInstance APIs, which stop the instance's compute charges but retain storage and backup costs, making it ideal for non-production workloads.
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: Use AWS Instance Scheduler to stop and start the RDS instance on a schedule. — Option D is correct because AWS Instance Scheduler is a fully managed solution designed specifically to start and stop RDS instances on a defined schedule, such as weekdays from 9 AM to 5 PM. This eliminates compute costs during non-business hours while preserving the instance's storage and configuration, making it the most cost-effective and reliable approach for a development environment.
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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