Question 818 of 302
SAA-C03 Design Cost-Optimized Architectures Practice Question
A startup runs two EC2-based workloads in the same AWS Region. Its customer-facing API is always on, and its nightly video transcoding fleet can restart jobs from checkpoints if an instance is interrupted. The finance team wants the lowest monthly compute cost without changing the application design. Which two actions should the team take? Select two.
⚠ Common exam trap
A common mix-up: candidates assume Reserved Instances are always the cheapest option, but for interruptible workloads like transcoding, Spot Instances provide far greater savings, and a Savings Plan better covers the steady-state API usage without locking into a specific instance family.
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
✓
Buy a Compute Savings Plan to cover the always-on API baseline usage.
A Compute Savings Plan offers the lowest cost for steady-state workloads like the always-on API, providing up to 66% savings over On-Demand in exchange for a 1- or 3-year commitment. It applies to any EC2 instance family within a Region, making it flexible and cost-effective for the baseline usage. Option C is correct because Spot Instances can be up to 90% cheaper than On-Demand and are ideal for fault-tolerant workloads like the transcoding fleet, which can resume from checkpoints if interrupted.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Purchase an All Upfront Reserved Instance for the transcoding fleet only.
Why it's wrong here
Reserved Instances fit steady, predictable usage, but this batch fleet is interruption-tolerant and variable.
When this WOULD be correct
If the question specified that both workloads must run continuously without interruption and the transcoding fleet cannot tolerate any interruptions, then purchasing All Upfront Reserved Instances for the transcoding fleet would provide the lowest cost for steady-state usage.
- ✓
Buy a Compute Savings Plan to cover the always-on API baseline usage.
Why this is correct
Savings Plans reduce cost for consistent compute usage and are well suited to the always-on API.
- ✓
Run the transcoding fleet on Spot Instances because interrupted jobs can resume from checkpoints.
Why this is correct
Spot Instances are ideal for flexible batch processing when interruptions are acceptable and checkpointing exists.
- ✗
Increase the API instance size so CPU utilization stays below 30 percent.
Why it's wrong here
Larger instances raise cost; right sizing should reduce waste, not add extra unused capacity.
When this WOULD be correct
In a scenario where the application is latency-sensitive and requires consistent low CPU utilization to handle sudden spikes, and cost is not the primary concern, increasing instance size could be correct to ensure performance.
- ✗
Move the API tier to Dedicated Hosts to improve isolation and lower spend.
Why it's wrong here
Dedicated Hosts usually increase cost and are used for licensing or compliance, not savings.
When this WOULD be correct
A question where the company has a per-socket or per-core software license (e.g., Windows Server, SQL Server) that requires dedicated physical servers to remain compliant. In that case, Dedicated Hosts can reduce licensing costs despite higher infrastructure spend.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The SAA-C03 exam frequently reuses these exact scenarios with slightly different constraints.
✓Buy a Compute Savings Plan to cover the always-on API baseline usage.Correct answer▾
Why this is correct
Savings Plans reduce cost for consistent compute usage and are well suited to the always-on API.
✗Purchase an All Upfront Reserved Instance for the transcoding fleet only.Wrong answer — click to see why▾
Why this is wrong here
The transcoding fleet can handle interruptions, so Spot Instances are cheaper than Reserved Instances. Purchasing All Upfront Reserved Instances for the transcoding fleet would lock in higher costs unnecessarily.
★ When this WOULD be the correct answer
If the question specified that both workloads must run continuously without interruption and the transcoding fleet cannot tolerate any interruptions, then purchasing All Upfront Reserved Instances for the transcoding fleet would provide the lowest cost for steady-state usage.
Why candidates choose this
Candidates may think Reserved Instances always provide the lowest cost, overlooking that Spot Instances are even cheaper for fault-tolerant workloads.
✗Increase the API instance size so CPU utilization stays below 30 percent.Wrong answer — click to see why▾
Why this is wrong here
Increasing instance size to keep CPU below 30% wastes compute capacity and increases cost, contradicting the goal of lowest monthly compute cost. The question explicitly states not to change application design, and this action changes the instance type.
★ When this WOULD be the correct answer
In a scenario where the application is latency-sensitive and requires consistent low CPU utilization to handle sudden spikes, and cost is not the primary concern, increasing instance size could be correct to ensure performance.
Why candidates choose this
Candidates may think that larger instances are more cost-effective per unit of compute, or that keeping CPU low improves reliability, but this overlooks that the startup's goal is to minimize total cost, not optimize utilization.
✗Move the API tier to Dedicated Hosts to improve isolation and lower spend.Wrong answer — click to see why▾
Why this is wrong here
Dedicated Hosts increase cost due to per-host billing and do not lower spend; they are used for licensing or compliance, not cost savings. The question asks for lowest compute cost, so this option is counterproductive.
★ When this WOULD be the correct answer
A question where the company has a per-socket or per-core software license (e.g., Windows Server, SQL Server) that requires dedicated physical servers to remain compliant. In that case, Dedicated Hosts can reduce licensing costs despite higher infrastructure spend.
Why candidates choose this
Candidates may think 'dedicated' implies better performance or security at lower cost, but Dedicated Hosts are actually more expensive and are chosen for licensing or regulatory reasons, not cost optimization.
Analysis generated from the official SAA-C03blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Last reviewed: Jun 11, 2026
This SAA-C03 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 SAA-C03 exam.
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