AZ-104 Deploy and Manage Azure Compute Practice Question
Two application VMs run in the same Azure region. The business wants to reduce the chance that both VMs are rebooted during planned host maintenance, but a datacenter outage is not part of the requirement. What should the administrator configure?
⚠ Common exam trap
Test-takers frequently confuse availability zones (which protect against datacenter outages) with availability sets (which protect against planned maintenance and hardware failures within a single datacenter), leading them to select availability zones even when the requirement explicitly excludes datacenter-level failures.
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
✓
Availability set
An availability set ensures that VMs are placed on different fault domains and update domains within the same Azure datacenter. This configuration guarantees that during planned host maintenance, only one update domain is rebooted at a time, reducing the chance that both VMs are rebooted simultaneously. Since the requirement explicitly excludes a datacenter outage, an availability set is the correct choice to protect against planned maintenance events.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Availability set
Why this is correct
An availability set spreads VMs across fault domains and update domains within a datacenter. This reduces the chance that all instances are affected by the same host maintenance event. It is the correct choice when the goal is host-level resilience rather than protection against an entire datacenter outage.
- ✗
Availability zone
Why it's wrong here
An availability zone places VMs in separate physical datacenters within a region, each with independent power, cooling, and networking. For this requirement—only protection from simultaneous host maintenance failures—zones are more than necessary and introduce cross-zone network latency and potentially different pricing. Additionally, zone support varies by region and VM SKU, so it is not the simplest targeted solution.
When this WOULD be correct
If the requirement were to protect against a full datacenter outage (e.g., power failure or network cut) while maintaining high availability, deploying VMs across multiple availability zones would be the correct answer.
- ✗
Azure Load Balancer
Why it's wrong here
Azure Load Balancer operates at Layer 4 to distribute incoming traffic across backend VMs, but it has no control over where those VMs are physically placed in the datacenter. Without an availability set, both VMs could be in the same fault domain or update domain, so the load balancer would still see simultaneous downtime during host maintenance. It is a traffic-distribution service, not a placement or availability construct.
When this WOULD be correct
An administrator needs to distribute incoming traffic across multiple VMs for high availability and fault tolerance, but the question does not mention maintenance or datacenter outage requirements.
- ✗
Virtual machine scale set
Why it's wrong here
A VM scale set can spread instances across fault and update domains, but it is primarily designed for elastic scaling and centralized management of many identical VMs. For just two application VMs needing host-maintenance protection, deploying a scale set adds operational overhead, such as instance count policies and autoscale rules, that an availability set avoids. The availability set directly fulfills the requirement in the simplest way, making a scale set an over-engineered choice.
When this WOULD be correct
A virtual machine scale set would be correct if the requirement was to automatically scale the number of VM instances based on demand (e.g., CPU load) while maintaining high availability across multiple VMs. For example, a web application that needs to handle variable traffic and requires auto-scaling and load balancing across instances.
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.
✓Availability setCorrect answer▾
Why this is correct
An availability set spreads VMs across fault domains and update domains within a datacenter. This reduces the chance that all instances are affected by the same host maintenance event. It is the correct choice when the goal is host-level resilience rather than protection against an entire datacenter outage.
✗Availability zoneWrong answer — click to see why▾
Why this is wrong here
Availability zones protect against datacenter-level failures, not planned host maintenance within a single datacenter. The question explicitly excludes datacenter outage requirements.
★ When this WOULD be the correct answer
If the requirement were to protect against a full datacenter outage (e.g., power failure or network cut) while maintaining high availability, deploying VMs across multiple availability zones would be the correct answer.
Why candidates choose this
Candidates confuse availability zones with availability sets, thinking both provide similar fault tolerance, but zones address broader failures (datacenter) while sets address host-level maintenance.
✗Azure Load BalancerWrong answer — click to see why▾
Why this is wrong here
Azure Load Balancer distributes traffic across VMs but does not provide any protection against planned host maintenance reboots; it does not ensure VMs are placed on separate update domains.
★ When this WOULD be the correct answer
An administrator needs to distribute incoming traffic across multiple VMs for high availability and fault tolerance, but the question does not mention maintenance or datacenter outage requirements.
Why candidates choose this
Candidates may think Load Balancer provides high availability by distributing traffic, confusing network-level load balancing with compute-level fault isolation.
✗Virtual machine scale setWrong answer — click to see why▾
Why this is wrong here
Virtual machine scale sets are designed for scaling out multiple VM instances and provide high availability through distribution across fault domains and update domains, but they are not the simplest solution for just two VMs. The question specifically asks to reduce reboots during planned host maintenance for two VMs, which is best achieved by an availability set that separates VMs into different update domains.
★ When this WOULD be the correct answer
A virtual machine scale set would be correct if the requirement was to automatically scale the number of VM instances based on demand (e.g., CPU load) while maintaining high availability across multiple VMs. For example, a web application that needs to handle variable traffic and requires auto-scaling and load balancing across instances.
Why candidates choose this
Candidates may think a scale set provides high availability by distributing VMs across fault and update domains, and it also offers auto-scaling, which seems like a more advanced solution. However, for a fixed set of two VMs, an availability set is simpler and sufficient.
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?”
Go deeper
Related to this question
Learn chapter
Managed Identities for Azure Resources
Key term
Region
A region is a distinct geographic location where a cloud provider operates multiple data centers that are connected by low-latency networks and provide cloud services.
Key term
Availability set
An Availability set is a cloud computing feature that groups virtual machines across multiple fault domains and update domains to ensure high availability during hardware failures or planned maintenance.
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JA
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.