SAA-C03 Design Cost-Optimized Architectures Practice Question

A retail company runs a stateless web tier on a fleet of On-Demand EC2 instances behind an Application Load Balancer. Traffic is steady and predictable throughout the year, and the team has committed to running this exact instance family and Region for at least the next three years. Leadership wants to reduce compute cost as much as possible while keeping the ability to change instance size within the same family. Which purchasing option should the solutions architect recommend?

⚠ Common exam trap

The trap here is assuming that the most flexible commitment always produces the lowest bill, when a narrower commitment to a known family and Region actually earns a deeper discount.

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

✓

A 3-year EC2 Instance Savings Plan with the All Upfront payment option

The workload is steady, long-lived, and already pinned to one instance family and Region, which is exactly the profile that EC2 Instance Savings Plans reward most heavily. Committing for three years with All Upfront yields the maximum discount, and the plan continues to allow size changes within the family, satisfying the flexibility requirement that rules out a size-locked reservation.

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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Spot Instances with a capacity-optimized allocation strategy
Why it's wrong here
Spot Instances offer the largest raw discount, but they can be reclaimed with a two-minute interruption notice. A customer-facing stateless web tier with steady, predictable traffic is better served by a firm capacity commitment than by interruption-tolerant capacity, and the requirement is cost reduction without sacrificing availability of the web tier.
✓
A 3-year EC2 Instance Savings Plan with the All Upfront payment option
Why this is correct
Because the workload is steady, stateless, and committed to a single instance family in a single Region for three years, an EC2 Instance Savings Plan gives the deepest discount of any commitment-based option. Paying All Upfront maximizes the discount further, and the plan still allows changing instance size within the same family, so operational flexibility is preserved.
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A 3-year Standard Reserved Instance for a specific instance size
Why it's wrong here
A zonal or size-specific Standard Reserved Instance locks the commitment to an exact instance size, which conflicts with the stated need to change instance size within the family. Although the discount is strong, the rigidity makes it a poorer fit than a Savings Plan, and converting or exchanging the reservation introduces extra effort that the team wanted to avoid.
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A 3-year Compute Savings Plan with the No Upfront payment option
Why it's wrong here
A Compute Savings Plan would lower the cost, but it applies a lower discount rate than an EC2 Instance Savings Plan when the family and Region are already fixed. Because the workload is locked to one instance family and one Region for three years, the broader flexibility of a Compute Savings Plan is paid for with a smaller discount, so it is not the maximum saving here.

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SAA-C03 Design Cost-Optimized Architectures Practice Question

Why each option matters

Option-by-option breakdown

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