AZ-104 Deploy and Manage Azure Compute Practice Question
You need to deploy 25 identical Azure virtual machines for a web application and scale the number of instances automatically based on CPU demand. Which Azure compute feature should you use?
⚠ Common exam trap
Candidates often confuse an availability set (which provides high availability) with a Virtual Machine Scale Set (which provides both identical deployment and autoscaling), leading them to select Option A because they focus on the 'identical VMs' requirement without recognizing that autoscaling is the key differentiator.
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
A Virtual Machine Scale Set (VMSS) is the correct Azure compute feature because it allows you to deploy and manage a group of identical, load-balanced VMs whose number can automatically increase or decrease in response to CPU demand using autoscale rules. This directly meets the requirement for 25 identical VMs with automatic scaling based on CPU metrics.
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
Why it's wrong here
An availability set is a fault-domain and update-domain boundary that increases the availability of your applications by ensuring that the VMs you place in it are distributed across different physical racks and maintenance windows. However, it lacks any deployment automation, instance orchestration, or autoscaling logic; you must manually create each VM and add it to the set, and you still cannot automatically scale beyond the initial explicit count. This makes it a resilience tool, not a scalable compute solution for a fleet of identical web servers.
When this WOULD be correct
When the question asks for a feature that ensures VMs are placed in separate fault domains to protect against hardware failures within a datacenter, and does not mention scaling or load-based automation.
- ✓
A Virtual Machine Scale Set
Why this is correct
A Virtual Machine Scale Set (VMSS) is a managed Azure service that deploys and manages a group of identically configured virtual machines, making it the ideal choice for running 25 identical web servers. VMSS integrates automatic scaling, enabling the fleet to grow or shrink based on CPU, memory, or custom metrics, and it can work with Azure Load Balancer or Application Gateway for traffic distribution. By defining a single VM image and configuration, you can effortlessly maintain a consistent environment across all instances, which is exactly what this workload requires.
- ✗
A Recovery Services vault
Why it's wrong here
A Recovery Services vault is a data protection resource in Azure, primarily used to store backup data and to configure Azure Site Recovery replication for disaster recovery. It does not provision, host, or organize virtual machines, and it cannot scale compute capacity or distribute traffic to a web application. Attempting to use it to deploy a web server fleet would be inappropriate because its purpose is safeguarding workloads, not running them.
When this WOULD be correct
When the question asks for a service to back up Azure VMs or implement site recovery, a Recovery Services vault would be the correct answer.
- ✗
Boot diagnostics
Why it's wrong here
Boot diagnostics is an Azure VM feature that captures serial port output and host-generated screenshots to help troubleshoot why a virtual machine failed to boot or became unresponsive. It is enabled per VM and provides no capabilities for provisioning multiple instances, coordinating autoscaling, or routing web traffic. While invaluable for diagnosing a single instance's startup problems, it cannot in any way deploy the 25 VMs needed for your web application.
When this WOULD be correct
You need to troubleshoot why a specific Azure VM fails to boot after a configuration change; boot diagnostics would be the correct feature to enable to capture the boot logs and screenshots.
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 SetCorrect answer▾
Why this is correct
A Virtual Machine Scale Set (VMSS) is a managed Azure service that deploys and manages a group of identically configured virtual machines, making it the ideal choice for running 25 identical web servers. VMSS integrates automatic scaling, enabling the fleet to grow or shrink based on CPU, memory, or custom metrics, and it can work with Azure Load Balancer or Application Gateway for traffic distribution. By defining a single VM image and configuration, you can effortlessly maintain a consistent environment across all instances, which is exactly what this workload requires.
✗An availability setWrong answer — click to see why▾
Why this is wrong here
An availability set provides high availability by distributing VMs across fault domains and update domains, but it does not support automatic scaling based on CPU demand. It is a static grouping, not a scaling solution.
★ When this WOULD be the correct answer
When the question asks for a feature that ensures VMs are placed in separate fault domains to protect against hardware failures within a datacenter, and does not mention scaling or load-based automation.
Why candidates choose this
Candidates may confuse availability sets with scale sets because both involve multiple VMs, and they might think availability sets also handle scaling due to the word 'set' implying grouping.
✗A Recovery Services vaultWrong answer — click to see why▾
Why this is wrong here
A Recovery Services vault is used for backup and disaster recovery, not for deploying or scaling virtual machines based on CPU demand.
★ When this WOULD be the correct answer
When the question asks for a service to back up Azure VMs or implement site recovery, a Recovery Services vault would be the correct answer.
Why candidates choose this
Candidates may confuse 'Recovery' with 'scaling' or think it provides some form of automatic recovery that includes scaling, but it is unrelated to compute scaling.
✗Boot diagnosticsWrong answer — click to see why▾
Why this is wrong here
Boot diagnostics captures serial console output and screenshots for troubleshooting VM boot failures, but it does not provide automatic scaling or deployment of multiple VMs.
★ When this WOULD be the correct answer
You need to troubleshoot why a specific Azure VM fails to boot after a configuration change; boot diagnostics would be the correct feature to enable to capture the boot logs and screenshots.
Why candidates choose this
Candidates may confuse boot diagnostics with a feature that helps manage VM health or performance, mistakenly thinking it can be used for scaling decisions based on CPU demand.
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
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.