SAP-C02 Continuous Improvement for Existing Solutions Practice Question
A company runs a batch processing job on Amazon EC2 instances that are part of an Auto Scaling group. The job runs every night and takes approximately 2 hours. The instances are launched using a launch template with a Spot Instance request. Recently, the job has been failing because Spot Instances are being reclaimed before the job completes. The company wants a cost-effective solution that ensures the job completes reliably. The job can handle interruptions by checkpointing. Which solution should the company implement?
⚠ Common exam trap
SAP-C02 often tests the misconception that Spot Instances alone can be made reliable by simply increasing instance size or that On-Demand is the only reliable option, overlooking the balanced approach of a mixed instances policy with a base of On-Demand capacity.
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
✓
Use a mixed instances policy with a percentage of On-Demand Instances as a fallback.
The mixed instances policy in an Auto Scaling group allows you to combine Spot and On-Demand Instances, with a configurable percentage of On-Demand capacity to act as a fallback when Spot capacity is unavailable or reclaimed. Since the job checkpoints and can tolerate interruptions, using a base of On-Demand instances ensures the job always has enough capacity to complete, while Spot instances provide cost savings for the remainder. This balances reliability and cost-effectiveness better than switching entirely to On-Demand or Reserved Instances.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the instance size to complete the job faster.
Why it's wrong here
Larger instances still run on Spot capacity, so reclamation interrupts the job regardless of size; the fix is a capacity-optimised allocation strategy or Spot Fleet with diversified pools and checkpointing. It tempts because bigger instances do shorten runtime, which suits deadline-bound jobs where interruption risk is negligible.
- ✓
Use a mixed instances policy with a percentage of On-Demand Instances as a fallback.
Why this is correct
A mixed instances policy blends Spot with a percentage of On-Demand capacity, so when Spot capacity is reclaimed the On-Demand fallback keeps the job running. Checkpointing handles interruption, and the blend preserves cost-effectiveness while guaranteeing completion.
- ✗
Switch to On-Demand Instances only.
Why it's wrong here
On-Demand Instances remove reclamation risk but charge full price for the entire two-hour run, discarding the checkpointing capability the stem explicitly offers. They are tempting as the obvious reliability fix, but On-Demand would be correct only if the workload could not tolerate interruption at all.
- ✗
Use Reserved Instances for the batch job.
Why it's wrong here
Reserved Instances give a billing discount on capacity the company still provisions and manages; they do not supply capacity when Spot reclaims instances mid-job. They are tempting for steady, predictable workloads, but here checkpointing already handles interruption, so the requirement is capacity that survives reclamation.
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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 SAP-C02 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 SAP-C02 exam.