SAA-C03 Design Cost-Optimized Architectures Practice Question
A company runs a media transcoding service on Amazon EC2 instances behind an Application Load Balancer. The workload is steady at 60% CPU utilization from 08:00 to 18:00 local time on weekdays and drops to under 5% overnight and on weekends. A solutions architect must reduce compute costs without changing the application code or degrading transcoding throughput during peak hours. (Choose two.)
⚠ Common exam trap
The trap here is assuming that any commitment-based discount must cover the entire fleet, when in fact the optimal design commits only to the always-on baseline and lets scheduled scaling handle the variable portion.
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
✓
Configure a scheduled scaling action on the Auto Scaling group to reduce desired capacity outside the 08:00-18:00 weekday window.
The workload has two distinct cost components: an always-on baseline and a predictable daily peak. A Compute Savings Plan discounts the continuous baseline usage across any instance family or Region, while scheduled scaling trims the fleet during the known low-traffic windows. Together they reduce spend without touching application code, preserving peak throughput, and avoiding the interruption risk that Spot would introduce.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Replace all On-Demand instances with Spot Instances in a single Availability Zone.
Why it's wrong here
Spot Instances can be reclaimed with a two-minute interruption notice, and concentrating the entire fleet in one Availability Zone removes fault isolation. For a transcoding service that must sustain throughput during peak hours, widespread Spot usage risks capacity loss and job failures, so it is not a safe way to guarantee the required performance.
- ✗
Move the transcoding workload to a larger instance type so fewer instances are needed at peak.
Why it's wrong here
Consolidating onto fewer, larger instances changes the instance mix but does not reduce total compute spend in a meaningful way, and it can reduce the Auto Scaling group's granularity for matching the daily curve. It also risks a coarser failure domain and does not address the overnight idle period where the real waste occurs.
- ✗
Enable detailed CloudWatch monitoring at one-minute resolution for every instance in the group.
Why it's wrong here
Detailed monitoring provides metrics at one-minute granularity and enables faster scaling reactions, but it does not lower the cost of the compute itself. It actually adds a small per-instance charge and does nothing to address the overnight idle capacity that dominates the savings opportunity in this scenario.
- ✓
Configure a scheduled scaling action on the Auto Scaling group to reduce desired capacity outside the 08:00-18:00 weekday window.
Why this is correct
Because demand is highly predictable by time of day, a scheduled scaling action can lower the minimum and desired capacity during nights and weekends so the group stops paying for idle instances. This matches capacity to the known traffic pattern and works alongside a commitment-based discount that covers only the always-on baseline.
- ✓
Purchase a 1-year Compute Savings Plan covering the baseline instance usage that runs every day.
Why this is correct
Compute Savings Plans apply to EC2 usage regardless of instance family, size, tenancy, OS, or Region, and they automatically cover the steady 24/7 baseline portion of this workload. Because roughly a third of the fleet runs continuously even overnight, locking in that floor at a discount reduces cost without affecting peak scaling behavior or requiring any application change.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
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.