AZ-900 Describe cloud concepts Practice Question
A company runs a batch job every night that takes 4 hours and cannot be interrupted. Which VM pricing model provides the lowest cost for this workload?
⚠ Common exam trap
It's easy for candidates to choose Spot VMs for cost savings without recognizing the 'cannot be interrupted' requirement, which directly contradicts Spot's eviction policy. They may also mistakenly assume Reserved Instances are always cheapest for predictable workloads, but a VM running only 4 hours per night does not use the reservation enough to offset paying for idle hours, so Pay-as-you-go is the lower-cost option.
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
✓
Pay-as-you-Go Instances
Pay-as-you-go pricing is the most cost-effective for a nightly 4-hour batch job because it charges only for the time the VM runs, without requiring an upfront commitment. Reserved Instances are designed for always-on workloads; using them for only 4 hours per night would waste the paid capacity during idle hours, making Pay-as-you-go cheaper for intermittent usage.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Spot VMs
Why it's wrong here
Spot VMs offer deep discounts but can be evicted at any time, making them unsuitable for workloads that cannot be interrupted.
- ✗
Reserved Instances (1 or 3-year)
Why it's wrong here
Reserved Instances provide significant discounts for always-on usage. For a VM running only 4 hours nightly, the cost per hour is effectively higher than Pay-as-you-go because you pay for idle capacity.
- ✓
Pay-as-you-Go Instances
Why this is correct
Pay-as-you-go charges only for actual usage with no upfront commitment, making it the lowest-cost option for a predictable but intermittent workload like a nightly 4-hour batch job.
- ✗
Dedicated Hosts
Why it's wrong here
Dedicated Hosts are expensive and designed for regulatory or licensing requirements, not for cost optimization on intermittent workloads.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-900 practice question is part of Courseiva's free Microsoft 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 AZ-900 exam.