CLF-C02 Billing, Pricing, and Support Practice Question
A company wants to purchase EC2 capacity that provides a discount over On-Demand pricing and is available only when AWS has excess capacity, with the option of interruption with a 2-minute warning. Which option is this?
⚠ Common exam trap
It's easy for candidates to confuse Spot Instances with Reserved Instances, thinking any discount means a commitment, but Spot Instances are interruptible and based on excess capacity, not a fixed-term contract.
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
✓
Spot Instances
Spot Instances (Option C) are correct because they offer a significant discount over On-Demand pricing but can be interrupted by AWS with a 2-minute warning when AWS needs the capacity back. This matches the scenario of purchasing EC2 capacity that is available only when AWS has excess capacity and includes the risk of interruption.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Reserved Instances
Why it's wrong here
Reserved Instances offer a lower hourly rate in exchange for a 1-year or 3-year commitment, not because they use spare capacity. They are not interruptible—once you purchase a Reserved Instance, your capacity is guaranteed for the entire term, regardless of AWS's spare capacity levels. The scenario specifically requires instances that can be interrupted when AWS needs the capacity back, and it makes no mention of a long-term commitment; therefore, Reserved Instances do not match the described use case.
- ✗
On-Demand Instances
Why it's wrong here
On-Demand Instances are incorrect as they do not provide a discount over their standard pricing and are not subject to interruption, failing to meet the scenario's requirements for cost savings and interruptibility based on excess capacity. This option is tempting because it offers immediate availability and sustained capacity for applications that cannot tolerate interruptions, making it suitable for critical, unpredictable workloads where flexibility and guaranteed uptime are prioritised over cost optimisation.
- ✓
Spot Instances
Why this is correct
Spot Instances are the only option that meets the scenario's requirements: they let you use AWS's unused EC2 capacity at a discount of up to 90% compared to On-Demand pricing. The trade-off is that AWS can reclaim this capacity with a 2-minute warning when it needs it back for other workloads, making them ideal for fault-tolerant, interruption-tolerant applications. The discount is directly tied to the availability of spare capacity, and if capacity is no longer available, the instance is interrupted—this matches the scenario precisely.
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Dedicated Instances
Why it's wrong here
Dedicated Instances run on physical hardware that is dedicated exclusively to your AWS account, providing strong isolation for compliance or licensing requirements. They are not related to spare capacity and do not receive any discount for being interruptible; in fact, they are more expensive than standard On-Demand Instances. Because the scenario asks for low-cost, interruptible capacity based on excess AWS resources, Dedicated Instances fail on both cost reduction and interruption tolerance, making them incorrect.
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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.