Which AWS purchasing option fits a partial serverless migration?
A company's application is running on Amazon EC2 instances. The company is planning a partial migration to a serverless architecture in the next year and wants to pay for resources up front. Which AWS purchasing option will optimize the company's costs?
Community Votes
69% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
The question tests whether you know which AWS discount model spans both EC2 and serverless compute — the trap is assuming Convertible Reserved Instances offer equivalent flexibility, when they only ever apply to EC2.
A company running on EC2 that plans a partial move to serverless within a year and wants to pay up front should choose Compute Savings Plans, because they discount EC2, Lambda, and Fargate under a single commitment. This page explains why Compute Savings Plans (D) beat Convertible Reserved Instances and EC2 Instance Savings Plans for a workload that will shift toward serverless.
Picking A (Convertible Reserved Instances) because "convertible" sounds flexible; that flexibility only lets you swap EC2 instance family, OS, or tenancy, so it cannot discount future Lambda or Fargate usage at all.
Community Discussion (11 comments)
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Expert Analysis
Why the Answer Is Correct
Compute Savings Plans (D) are the only option here that discounts the whole compute footprint the company is heading toward: they apply to EC2, AWS Lambda, and AWS Fargate usage, regardless of instance family, region, tenancy, or operating system. The company wants to pay up front, and Compute Savings Plans explicitly support an All Upfront payment option in exchange for a 1- or 3-year commitment, which maximizes the discount. Because the migration is only partial and spread over the next year, the plan's service-agnostic scope means the same commitment keeps saving money as EC2 usage shrinks and Lambda/Fargate usage grows. That directly satisfies the scenario's two constraints: upfront payment and a workload that becomes partly serverless.Why the Other Options Are Wrong
A (Convertible Reserved Instances) is EC2-only — you can exchange them for a different instance family, OS, or tenancy, but they will never cover Lambda or Fargate, so the serverless portion of the migration earns no discount. C (EC2 Instance Savings Plans) locks the discount to a single instance family in a single region, so they are even narrower than Convertible RIs for a workload in transition. B (Spot Instances) offer deep discounts but are spare capacity that can be reclaimed with a two-minute interruption notice, and they have nothing to do with paying up front for a predictable commitment. In short, A and C are EC2-scoped and B is not a commitment-based upfront purchase at all.Community Comment Notes
Supercell argued that Compute Savings Plans are the best fit here, and several voters agreed with "SERVERLESS = Compute Saving Plans" reasoning, echoing that the plan spans Lambda and Fargate. Dissent came mainly from ahadh7621, who posted that C is correct because the migration is only "a PARTIAL migration to serverless architecture" — but partial migrations still generate some serverless spend that EC2 Instance Savings Plans simply cannot discount. CharmaineBowman and f964633 backed A, describing how Convertible RIs let you "change instance families, operating systems, or tenancies," which is true but irrelevant to Lambda. chalaka summarized the winning rationale well: Compute Savings Plans "apply to a wide range of compute usage across Amazon EC2, AWS Lambda, and AWS Fargate."Verdict
D is the correct choice: it is the only upfront-paid, commitment-based discount that follows the workload into serverless.Official Reference
Exam Strategy
When a stem mentions serverless, Lambda, or Fargate alongside EC2, treat "spanning services" as the deciding keyword and eliminate any EC2-only discount (Standard RIs, Convertible RIs, EC2 Instance Savings Plans). Only Compute Savings Plans cross the boundary from EC2 to serverless. Also note any "pay up front" phrasing — it points to a commitment-based plan, not Spot capacity.
Frequently Asked Questions
Do Compute Savings Plans cover Lambda and Fargate, not just EC2?
Yes. Compute Savings Plans apply to EC2, AWS Lambda, and AWS Fargate usage regardless of instance family, region, OS, or tenancy, which is why they suit a workload moving partly to serverless.
Why isn't the EC2 Instance Savings Plan (C) the answer for a partial migration?
It cuts costs only for a chosen EC2 instance family in a specific region, so any serverless usage from the migration — Lambda or Fargate — receives no discount at all.
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