Most Cost-Effective Billing Model for Intermittent EC2 Workloads
A company is running a reporting web server application on Amazon EC2 instances. The application runs once every week and once again at the end of the month. The EC2 instances can be shut down when they are not in use. What is the MOST cost-effective billing model for this use case?
Community Votes
67% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
Tests understanding of cost optimization for intermittent workloads where instances are shut down frequently, ruling out long-term commitments.
Determines the optimal AWS billing model for periodic, non-continuous EC2 usage by comparing On-Demand Instances against Reserved and Capacity Reservation options.
Candidates often choose Reserved Instances or Capacity Reservations, mistakenly believing they save money despite the low utilization frequency.
Community Discussion (4 comments)
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Expert Analysis
Why the Answer Is Correct
On-Demand Instances (D) are the most cost-effective option because the workload is highly intermittent (once a week and once a month). With On-Demand pricing, you pay only for the compute time used without any upfront commitment or long-term contract, which minimizes costs for sporadic usage.Why the Other Options Are Wrong
Standard Reserved Instances (A) and Convertible Reserved Instances (B) require a 1-year or 3-year commitment for significant discounts, making them expensive for workloads that run less than 5% of the time. On-Demand Capacity Reservations (C) guarantee capacity in an Availability Zone but do not offer pricing discounts compared to standard On-Demand; they are intended for ensuring availability, not reducing costs.Community Comment Notes
The community consensus strongly favors Option D. As Yomijohnson noted, "On-Demand Instances are ideal for intermittent workloads... allowing the company to pay only for the compute time they use." Yak_Yeti clarified that Capacity Reservations serve a different purpose regarding availability rather than cost savings for idle periods.Exam Strategy
Always evaluate the utilization rate before choosing Reserved Instances. If usage is sporadic or unpredictable, On-Demand Instances are typically cheaper than committing to reservations.
Frequently Asked Questions
Why not use Spot Instances?
Spot Instances are cheaper but can be interrupted. The question asks for the most cost-effective billing model among standard choices, and On-Demand provides necessary reliability for scheduled reporting without interruption risk.
Do Capacity Reservations save money?
No. Capacity Reservations charge the same On-Demand rate but guarantee capacity. They do not reduce costs for unused time.
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