AZ-104 Deploy and Manage Azure Compute Practice Question
A stateless API must automatically add or remove identical VM instances when CPU usage crosses thresholds. The team also wants Microsoft to distribute instances across fault domains when possible. Which service should the administrator deploy?
⚠ Common exam trap
It's easy for candidates to confuse an availability set with a scale set, thinking that an availability set provides autoscaling, but it only offers fault domain distribution without any automatic instance management.
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 choice because it provides built-in autoscaling capabilities that automatically add or remove identical VM instances based on CPU usage thresholds. VMSS also supports automatic distribution of instances across fault domains when configured with a fault domain count greater than 1, meeting the requirement for Microsoft to distribute instances across fault domains.
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 logical grouping of VMs that spreads instances across fault domains and update domains to protect against hardware failures and maintenance downtime, but it has no scaling logic — it neither monitors demand nor changes the number of running VMs. You must manually add or remove VMs from the set. Therefore, while it improves resiliency, it cannot satisfy the automatic scale-out/in requirement for identical stateless VM instances.
When this WOULD be correct
An availability set would be correct when the requirement is to ensure high availability for a fixed set of VMs (e.g., a multi-tier application) by distributing them across fault domains and update domains, without any need for autoscaling.
- ✗
Azure Load Balancer
Why it's wrong here
Azure Load Balancer is a Layer 4 network component that distributes inbound traffic to a backend pool of existing VMs and uses health probes to remove unresponsive instances from rotation, but it has no knowledge of capacity or demand and cannot create, delete, or scale VM instances. It may be paired with a scale set to route traffic, but the load balancer itself never triggers scaling operations. Hence, it addresses traffic distribution, not lifecycle management of identical VMs.
When this WOULD be correct
An administrator needs to distribute incoming network traffic across multiple VMs in the same region to ensure high availability and no single point of failure, without requiring automatic scaling or fault domain distribution.
- ✓
A 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 fits stateless workloads well and supports placement across fault domains in supported configurations, which helps improve resiliency while also meeting the demand-based scaling requirement.
- ✗
Azure App Service
Why it's wrong here
Azure App Service is a fully managed PaaS offering that runs web apps, API apps, and mobile backends, not raw VM instances; even though its App Service Plan supports autoscale rules based on metrics or schedules, the underlying compute is a shared or dedicated app service plan that abstracts away VM identities and fault domain placement. The question specifically calls for identical VM instances and VM-centric fault domain behavior, which App Service cannot expose. Thus, while autoscaling is built in, it applies to the wrong hosting model.
When this WOULD be correct
A question asking for a fully managed service to host a web application with built-in scaling and high availability, without needing to manage VMs. For example: 'Which service should be used to host a web app that automatically scales based on HTTP traffic and provides built-in load balancing?'
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 is designed for identical VM instances that can scale out and scale in automatically. It fits stateless workloads well and supports placement across fault domains in supported configurations, which helps improve resiliency while also meeting the demand-based scaling requirement.
✗An availability setWrong answer — click to see why▾
Why this is wrong here
An availability set only provides high availability for VMs by distributing them across fault domains and update domains, but it does not support automatic scaling based on CPU thresholds or manage identical VM instances as a group.
★ When this WOULD be the correct answer
An availability set would be correct when the requirement is to ensure high availability for a fixed set of VMs (e.g., a multi-tier application) by distributing them across fault domains and update domains, without any need for autoscaling.
Why candidates choose this
Candidates may confuse the fault domain distribution capability of availability sets with the autoscaling and fault domain distribution of virtual machine scale sets, assuming availability sets can also handle scaling.
✗Azure Load BalancerWrong answer — click to see why▾
Why this is wrong here
Azure Load Balancer distributes traffic across existing VMs but does not automatically add or remove VM instances based on CPU thresholds. It lacks autoscaling and fault domain distribution capabilities for VM instances.
★ When this WOULD be the correct answer
An administrator needs to distribute incoming network traffic across multiple VMs in the same region to ensure high availability and no single point of failure, without requiring automatic scaling or fault domain distribution.
Why candidates choose this
Candidates may confuse load balancing with autoscaling, thinking that a load balancer can automatically manage instance counts, or they may overlook the requirement for fault domain distribution that is not provided by Azure Load Balancer.
✗Azure App ServiceWrong answer — click to see why▾
Why this is wrong here
Azure App Service is a platform-as-a-service for hosting web apps, APIs, and mobile backends, but it does not provide the ability to automatically add or remove identical VM instances based on CPU thresholds or distribute instances across fault domains. It abstracts away the underlying VMs, so you cannot manage VM-level scaling or fault domain distribution.
★ When this WOULD be the correct answer
A question asking for a fully managed service to host a web application with built-in scaling and high availability, without needing to manage VMs. For example: 'Which service should be used to host a web app that automatically scales based on HTTP traffic and provides built-in load balancing?'
Why candidates choose this
Candidates may confuse App Service's auto-scaling capabilities with VM-level scaling, or think that App Service can handle stateless APIs with fault domain distribution, not realizing it abstracts away the VM layer.
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.