CLF-C02 Billing, Pricing, and Support Practice Question

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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  On-Demand Instances

  Why it's wrong here

  On-Demand Instances give you immediate capacity with no upfront payment and no long-term commitment, and they are guaranteed only to be interrupted by typical service events rather than spot reclaims. The trade-off is that On-Demand is the most expensive per-hour pricing model, charging the full list price for every second of usage. Because your workload can tolerate interruption and checkpoint, paying this premium for uninterrupted execution is unnecessary, so On-Demand cannot be the lowest-cost option for this batch processing scenario.

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  Reserved Instances (1-year, No Upfront)

  Why it's wrong here

  Reserved Instances (1-year, No Upfront) require a firm 1- or 3-year term commitment in exchange for a discounted hourly rate. Even with No Upfront, you are still locked into paying for the instance for the entire term, which is wasteful when your batch jobs are unpredictable and may not run continuously. No Upfront also means a higher effective hourly rate than full or partial upfront, so it neither provides checkpoint tolerance nor the absolute lowest cost for a short-lived, interruptible workload.

• ✓

  Spot Instances

  Why this is correct

  Spot Instances offer EC2 compute capacity at up to a 90% discount compared to On-Demand because AWS can reclaim that capacity with a two-minute warning when it needs the resources back. For a batch job that can save its progress and resume after interruption, Spot Instances are the ideal match because the workload's fault tolerance makes the risk of interruption acceptable. There is no long-term commitment, and you pay per second only for the time the instance actually runs, making Spot the lowest-cost choice for fault-tolerant, transient, or checkpointable workloads.

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  Dedicated Hosts

  Why it's wrong here

  Dedicated Hosts grant you a physical server entirely dedicated to your account, which is primarily used to satisfy software licensing that is tied to CPU sockets or cores. However, this option is typically the most expensive EC2 pricing model because you are billed for the entire host, regardless of how many instances you run, and each instance still incurs On-Demand charges. For an unpredictable batch job with no special licensing constraints, a Dedicated Host provides zero cost benefit and only amplifies waste, so it is completely inappropriate for lowest-cost processing.

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