AZ-104 Deploy and Manage Azure Compute Practice Question
Exhibit
Monitoring summary: - CPU averages 18% from 00:00 to 08:00 - CPU averages 74% from 09:00 to 17:00 - CPU averages 22% after 18:00 - The application is stateless and can run on any instance
Based on the exhibit, which Azure compute service should you deploy for a stateless web app that needs more instances during business hours and fewer at night?
⚠ Common exam trap
Many candidates confuse availability sets (high availability) with autoscaling, or think a single large VM can handle variable load by resizing, but autoscaling requires horizontal scaling via VMSS.
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
✓
A virtual machine scale set with autoscale rules.
A virtual machine scale set with autoscale rules is the correct choice because it automatically adjusts the number of VM instances based on demand, scaling out during business hours and scaling in at night. This matches the stateless web app requirement, as scale sets are designed for stateless workloads where instances can be added or removed without data loss.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A single larger virtual machine.
Why it's wrong here
A single larger virtual machine provides only vertical scaling, which has hard limits based on the VM size family and requires a resizing operation (often with a reboot) to change capacity. It cannot automatically add or remove compute resources in response to CPU or traffic metrics, and it remains a single point of failure. For a stateless application with predictable spikes, horizontal scaling through a virtual machine scale set is the appropriate approach, not relying on a fixed, monolithic VM.
When this WOULD be correct
This option would be correct for a legacy application that requires a single, powerful VM with high compute or memory resources and does not support horizontal scaling, such as a monolithic database server or a compute-intensive simulation.
- ✓
A virtual machine scale set with autoscale rules.
Why this is correct
A virtual machine scale set is the right choice because it can run multiple identical instances and scale them automatically when demand changes. The exhibit shows predictable workload spikes, and the app is stateless, so instances can be added or removed without affecting user sessions.
- ✗
An availability set with two VMs.
Why it's wrong here
An availability set with two VMs improves fault tolerance by spreading instances across fault and update domains, but the workload capacity is fixed at two instances. It has no built-in automatic scale-out or scale-in capability based on CPU or demand metrics, so it cannot adapt to the predictable spikes shown in the exhibit. Additionally, you would still need to manually resize or add VMs to handle load changes, which defeats the requirement for automatic elasticity.
When this WOULD be correct
When the question requires high availability for a critical application (e.g., a database tier) that must survive planned or unplanned downtime, and scaling is not needed.
- ✗
A dedicated host with one VM per host.
Why it's wrong here
A dedicated host with one VM per host is intended for scenarios that require physical server isolation, such as regulatory compliance or using existing server licenses, not for achieving elasticity. It does not provide any automatic scaling mechanisms, and the number of running instances is limited by the number of hosts you manually deploy. This option incurs fixed high costs because each host is reserved as a whole, and it fails to address the operational requirement to dynamically respond to workload spikes.
When this WOULD be correct
A dedicated host would be correct for a question requiring a solution for a regulated workload that must run on a dedicated physical server (e.g., for compliance with security or licensing requirements) and does not need autoscaling, such as a legacy application that requires fixed hardware resources.
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 AZ-104 exam frequently reuses these exact scenarios with slightly different constraints.
✓A virtual machine scale set with autoscale rules.Correct answer▾
Why this is correct
A virtual machine scale set is the right choice because it can run multiple identical instances and scale them automatically when demand changes. The exhibit shows predictable workload spikes, and the app is stateless, so instances can be added or removed without affecting user sessions.
✗A single larger virtual machine.Wrong answer — click to see why▾
Why this is wrong here
A single larger virtual machine cannot scale out to meet variable demand; it only scales up (increase size), which does not automatically adjust instance count based on time or load.
★ When this WOULD be the correct answer
This option would be correct for a legacy application that requires a single, powerful VM with high compute or memory resources and does not support horizontal scaling, such as a monolithic database server or a compute-intensive simulation.
Why candidates choose this
Candidates may think a larger VM can handle peak loads by upgrading its size, but they overlook the need for automatic scaling across multiple instances to match fluctuating demand.
✗An availability set with two VMs.Wrong answer — click to see why▾
Why this is wrong here
An availability set with two VMs provides high availability but does not automatically scale instances based on time or load; it cannot increase or decrease instances to match business hours.
★ When this WOULD be the correct answer
When the question requires high availability for a critical application (e.g., a database tier) that must survive planned or unplanned downtime, and scaling is not needed.
Why candidates choose this
Candidates may confuse high availability (availability set) with scalability, or think that two VMs can be manually started/stopped to match demand, ignoring the need for automated scaling.
✗A dedicated host with one VM per host.Wrong answer — click to see why▾
Why this is wrong here
A dedicated host provides physical isolation and dedicated resources for compliance or licensing needs, but it does not offer autoscaling to adjust instances based on time-of-day demand. The question requires a solution that scales instances up during business hours and down at night, which a dedicated host cannot achieve.
★ When this WOULD be the correct answer
A dedicated host would be correct for a question requiring a solution for a regulated workload that must run on a dedicated physical server (e.g., for compliance with security or licensing requirements) and does not need autoscaling, such as a legacy application that requires fixed hardware resources.
Why candidates choose this
Candidates may confuse dedicated hosts with high-availability or scaling solutions, thinking that dedicating physical hardware ensures performance during peak times, but they overlook the lack of dynamic scaling capability.
Analysis generated from the official AZ-104blueprint 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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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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