CLF-C02 Billing, Pricing, and Support Practice Question
A company runs a production MySQL database on Amazon RDS. The workload has a steady baseline usage that requires a db.r5.large instance most of the time, but during end-of-month processing, the database needs to scale up to a db.r5.xlarge for a few days. The company wants to maximize cost savings while retaining the ability to temporarily scale up the instance during those peaks and still receive a discounted rate. Which purchasing option should the company choose?
⚠ Common exam trap
Many candidates confuse Compute Savings Plans with RDS Reserved Instances, not realizing that Compute Savings Plans only apply to EC2 and Fargate, not to RDS database instances.
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
✓
Convertible Reserved Instance
Convertible Reserved Instances (RIs) allow you to change instance attributes (such as size) during the term, which fits the need to temporarily scale from db.r5.large to db.r5.xlarge for a few days each month. They offer a significant discount over On-Demand pricing (typically 30-50%) while retaining flexibility to modify the instance type. Standard RIs lock you into a specific instance family and size, making them unsuitable for this variable workload.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Standard Reserved Instance
Why it's wrong here
Standard Reserved Instances provide a discount but do not allow you to change the instance size or family during the term. If you scale up to a db.r5.xlarge, you would lose the discount on that instance, making this option less cost-effective for the scenario.
When this WOULD be correct
A company has a predictable, steady-state workload with no need to change instance size or family, and wants the maximum discount for a 1- or 3-year commitment. For example, a database with constant usage that never requires scaling.
- ✓
Convertible Reserved Instance
Why this is correct
Convertible Reserved Instances for RDS offer the flexibility to modify instance attributes (such as size) during the commitment term while still receiving a discounted rate. This allows the company to temporarily scale up to a db.r5.xlarge during peak periods without losing the RI discount.
- ✗
Compute Savings Plan
Why it's wrong here
Compute Savings Plans offer discounted EC2, Fargate, and Lambda usage in exchange for a one- or three-year hourly spend commitment, but they do not cover Amazon RDS instances. Since RDS pricing is billed separately from EC2 compute and is not a Savings Plans-eligible service, committing to a Compute Savings Plan would only discount non-RDS compute and leave the database at full On-Demand rates. Therefore this option cannot reduce the cost of the MySQL RDS production workload described.
When this WOULD be correct
A company runs a mix of EC2 instances, containers, and serverless functions with steady usage, and wants flexibility across instance families and regions while still getting a discount. Compute Savings Plan would be ideal.
- ✗
On-Demand
Why it's wrong here
With Amazon RDS On-Demand pricing, you pay per second or per hour for the exact capacity you provision with no upfront commitment or long-term contract. While this gives you the freedom to scale the instance up temporarily during peak periods, the steady baseline workload runs 24/7, and On-Demand's highest per-unit rate means you forgo the significant discounts available through Reserved Instances. Thus it does not meet the company's cost-optimization goal for a predictable, always-on production database.
When this WOULD be correct
A company has unpredictable, spiky workloads with no steady baseline and cannot commit to any instance usage. They need maximum flexibility to scale up or down at any time without upfront payment or long-term commitment.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The CLF-C02 exam frequently reuses these exact scenarios with slightly different constraints.
✓Convertible Reserved InstanceCorrect answer▾
Why this is correct
Convertible Reserved Instances for RDS offer the flexibility to modify instance attributes (such as size) during the commitment term while still receiving a discounted rate. This allows the company to temporarily scale up to a db.r5.xlarge during peak periods without losing the RI discount.
✗Standard Reserved InstanceWrong answer — click to see why▾
Why this is wrong here
Standard Reserved Instances require a fixed instance size (e.g., db.r5.large) and cannot be changed to a larger size (db.r5.xlarge) during peak periods, so they do not support the temporary scaling needed.
★ When this WOULD be the correct answer
A company has a predictable, steady-state workload with no need to change instance size or family, and wants the maximum discount for a 1- or 3-year commitment. For example, a database with constant usage that never requires scaling.
Why candidates choose this
Candidates may think any Reserved Instance offers cost savings and overlook the flexibility requirement, assuming Standard RIs can be modified to larger sizes, which they cannot.
✗Compute Savings PlanWrong answer — click to see why▾
Why this is wrong here
Compute Savings Plans apply to compute usage across EC2, Fargate, and Lambda, but not to RDS instance modifications. They do not allow scaling RDS instance sizes like Convertible RIs do.
★ When this WOULD be the correct answer
A company runs a mix of EC2 instances, containers, and serverless functions with steady usage, and wants flexibility across instance families and regions while still getting a discount. Compute Savings Plan would be ideal.
Why candidates choose this
Candidates may confuse Compute Savings Plans with RDS-specific savings, or think that any 'savings plan' covers all compute services including RDS, but RDS requires its own Reserved Instance or Savings Plan.
✗On-DemandWrong answer — click to see why▾
Why this is wrong here
On-Demand pricing does not provide any discount or reservation, so it fails to maximize cost savings for the steady baseline usage. The company needs a discounted rate, which On-Demand does not offer.
★ When this WOULD be the correct answer
A company has unpredictable, spiky workloads with no steady baseline and cannot commit to any instance usage. They need maximum flexibility to scale up or down at any time without upfront payment or long-term commitment.
Why candidates choose this
Candidates may think On-Demand is the simplest way to handle temporary scaling, overlooking the requirement for cost savings and discounted rates for the steady baseline.
Analysis generated from the official CLF-C02blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CLF-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CLF-C02 exam.