Quick Answer
The answer is a Virtual Machine Scale Set (VMSS). This is the correct choice because VMSS is specifically designed to deploy and manage a group of identical, load-balanced virtual machines, and it integrates directly with Azure autoscale to automatically adjust the number of instances based on performance metrics like CPU demand. For the AZ-104 exam, this question tests your understanding of scaling solutions: while individual VMs with autoscale can work, VMSS is the only feature that treats the group as a single logical unit with identical configurations, making it the proper answer for deploying 20 identical VMs. A common trap is confusing VMSS with a simple availability set or a load balancer alone—remember that VMSS combines load balancing, identical configuration, and autoscaling into one service. Memory tip: think "Scale Set = Same Set," meaning all VMs are identical and scale together as a set.
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.
You need to deploy 20 identical Azure virtual machines for a web application and automatically scale the number of instances based on CPU demand. Which Azure feature should you use?
An availability set
Why wrong: Availability sets improve resiliency but do not support autoscaling.
A Virtual Machine Scale Set
Scale Sets provide grouped VM deployment and autoscaling.
A Recovery Services vault
Why wrong: A Recovery Services vault is for backup and recovery.
Boot diagnostics
Why wrong: Boot diagnostics helps troubleshoot VM startup issues and does not manage fleet scaling.
Answer choices
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
A Virtual Machine Scale Set (VMSS) is the correct Azure feature because it allows you to deploy and manage a group of identical, load-balanced VMs that can automatically scale in or out based on CPU demand using autoscale rules. This directly meets the requirement for deploying 20 identical VMs with automatic scaling based on a performance metric like CPU utilization.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
An availability set
Why it's wrong here
Availability sets improve resiliency but do not support autoscaling.
A Virtual Machine Scale Set
Why this is correct
Scale Sets provide grouped VM deployment and autoscaling.
Related concept
Read the scenario before looking for a memorised answer.
A Recovery Services vault
Why it's wrong here
A Recovery Services vault is for backup and recovery.
Boot diagnostics
Why it's wrong here
Boot diagnostics helps troubleshoot VM startup issues and does not manage fleet scaling.
Common exam traps
The trap here is that candidates often confuse an availability set (which provides high availability through fault domain distribution) with a Virtual Machine Scale Set (which provides both high availability and automatic scaling), leading them to select Option A when the question explicitly requires automatic scaling based on demand.
Detailed technical explanation
Under the hood, a VMSS uses an autoscale profile that defines the minimum, maximum, and default instance counts, and you configure autoscale rules based on metrics like Percentage CPU (gathered from the Azure Diagnostics extension or the VM's host metrics). The scale-out and scale-in actions are triggered when the metric crosses defined thresholds for a specified duration (e.g., average CPU > 75% for 10 minutes), and the VMSS uses a scale policy (e.g., 'NewestVM' or 'OldestVM') to determine which instances to remove during scale-in. In a real-world scenario, you would also configure a load balancer or Application Gateway in front of the scale set to distribute traffic evenly across the instances.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
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FAQ
Deploy and Manage Azure Compute — This question tests Deploy and Manage Azure Compute — Read the scenario before looking for a memorised answer..
The correct answer is: A Virtual Machine Scale Set — A Virtual Machine Scale Set (VMSS) is the correct Azure feature because it allows you to deploy and manage a group of identical, load-balanced VMs that can automatically scale in or out based on CPU demand using autoscale rules. This directly meets the requirement for deploying 20 identical VMs with automatic scaling based on a performance metric like CPU utilization.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
About these practice questions
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A stateless web application needs a group of identical Azure VMs that can automatically add more instances during the workday and remove them at night based on CPU usage. What should the administrator deploy?
easyWhy B: A virtual machine scale set (VMSS) with autoscale rules is the correct solution because it provides a group of identical, load-balanced VMs that can automatically scale out (add instances) during high CPU usage in the workday and scale in (remove instances) at night based on CPU thresholds. This matches the stateless, elastic requirement perfectly, as VMSS is designed for horizontal scaling of identical instances with autoscale policies tied to metrics like CPU percentage.
Variation 2. A web front end must automatically add or remove instances based on demand. The application is stateless and all instances should be managed as one group. Which Azure service should you use?
easyWhy B: Virtual Machine Scale Sets (VMSS) automatically scale the number of VM instances in or out based on demand or a defined schedule, making them ideal for stateless, horizontally scalable applications. They manage all instances as a single group behind a load balancer, ensuring uniform configuration and seamless scaling without manual intervention.
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Last reviewed: Jun 11, 2026
This AZ-104 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-104 exam.
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