An Azure virtual machine scale set is the correct choice because it provides native autoscaling based on CPU usage metrics, allowing a stateless web app to automatically add VM instances during business hours and remove them at night without manual intervention. This works by configuring a scale-out rule when average CPU exceeds a threshold and a scale-in rule when it drops, combined with a scheduled profile to enforce the time-based scaling pattern. On the AZ-104 exam, this scenario tests your understanding of when to choose a virtual machine scale set over standalone VMs or other compute services, and a common trap is selecting Azure App Service autoscaling—but remember that VMSS is the only service that directly manages a group of identical VMs with both metric-based and scheduled scaling. A helpful memory tip: think of VMSS as “elastic VMs on a schedule,” where CPU drives the day and time drives the night.
AZ-104 Deploy and Manage Azure Compute Practice Question
This AZ-104 practice question tests your understanding of deploy and manage azure compute. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Scaling requirement:
- Workload is stateless
- Start with 2 instances
- Increase capacity when average CPU stays above 70% for 10 minutes
- Decrease capacity when demand drops
- All instances should run the same image and configuration
Based on the exhibit, a stateless web app must add VM instances during business hours and remove them at night based on CPU usage. Which Azure service should the administrator deploy?
Scaling requirement:
- Workload is stateless
- Start with 2 instances
- Increase capacity when average CPU stays above 70% for 10 minutes
- Decrease capacity when demand drops
- All instances should run the same image and configuration
A
An availability set with two virtual machines.
Why wrong: An availability set improves resilience, but it does not automatically add or remove VM instances based on load.
B
An Azure virtual machine scale set.
A virtual machine scale set is designed for identical VM instances that can scale out and scale in automatically. It works well for stateless workloads, and autoscale rules can use CPU thresholds or schedules to adjust capacity over time. This exactly matches the requirement for business-hour scaling.
C
A single Azure VM with a larger size.
Why wrong: Resizing one VM can improve performance, but it does not provide automatic horizontal scaling for changing demand.
D
A recovery services vault.
Why wrong: A recovery services vault is used for backup and restore, not autoscaling compute resources.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
An Azure virtual machine scale set.
An Azure virtual machine scale set (VMSS) is the correct choice because it automatically scales the number of VM instances in or out based on CPU usage metrics, and it supports scheduled scaling to add instances during business hours and remove them at night. This aligns with the stateless web app requirement for elastic, automated scaling without manual intervention.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
An availability set with two virtual machines.
Why it's wrong here
An availability set improves resilience, but it does not automatically add or remove VM instances based on load.
✓
An Azure virtual machine scale set.
Why this is correct
A virtual machine scale set is designed for identical VM instances that can scale out and scale in automatically. It works well for stateless workloads, and autoscale rules can use CPU thresholds or schedules to adjust capacity over time. This exactly matches the requirement for business-hour scaling.
Related concept
Read the scenario before looking for a memorised answer.
✗
A single Azure VM with a larger size.
Why it's wrong here
Resizing one VM can improve performance, but it does not provide automatic horizontal scaling for changing demand.
✗
A recovery services vault.
Why it's wrong here
A recovery services vault is used for backup and restore, not autoscaling compute resources.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse availability sets (which provide high availability) with scale sets (which provide autoscaling), leading them to pick Option A for a scenario that explicitly requires dynamic scaling based on load and schedule.
Detailed technical explanation
How to think about this question
VMSS uses an autoscale profile with rules based on metrics like CPU percentage (e.g., scale out when CPU > 75% for 5 minutes) and can also use scheduled conditions to set a specific capacity during business hours. Under the hood, VMSS leverages the Azure Load Balancer or Application Gateway to distribute traffic across instances, and each instance is created from a uniform image or custom VM image, ensuring statelessness. A real-world scenario is an e-commerce site that scales out to 20 instances during the day and scales in to 3 at night, reducing costs while maintaining performance.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-104 question in full detail.
Deploy and Manage Azure Compute — This question tests Deploy and Manage Azure Compute — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: An Azure virtual machine scale set. — An Azure virtual machine scale set (VMSS) is the correct choice because it automatically scales the number of VM instances in or out based on CPU usage metrics, and it supports scheduled scaling to add instances during business hours and remove them at night. This aligns with the stateless web app requirement for elastic, automated scaling without manual intervention.
What should I do if I get this AZ-104 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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