AZ-104 Deploy and Manage Azure Compute Practice Question
Two app VMs must stay available during planned host maintenance in the same region. Datacenter-level redundancy is not required, but the VMs should be spread across update domains. What should you configure?
⚠ Common exam trap
Test-takers frequently confuse availability zones (which provide datacenter-level redundancy) with availability sets (which provide intra-datacenter fault and update domain distribution), leading them to select availability zones even when the question explicitly states datacenter-level redundancy is not required.
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 logically groups VMs to protect against planned maintenance events by distributing them across up to 3 fault domains and 20 update domains. This ensures that during host maintenance, only one update domain is taken offline at a time, keeping the other VMs available. Since datacenter-level redundancy is not required, an availability set is the correct choice.
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 logically groups VMs so Azure distributes them across fault domains (isolated power/network) and update domains (host groups rebooted sequentially). During planned host maintenance, Azure updates one update domain at a time, so at least one VM in the set remains online. This is the targeted placement control that directly matches the scenario's requirement.
- ✗
Availability zone
Why it's wrong here
Availability zones provide physically separate datacenter locations within a region, protecting against a complete datacenter failure. Planned host maintenance, however, occurs within a single datacenter and is already mitigated by update domains in an availability set. Deploying across zones is overkill, adds cross-zone network latency, and requires extra architecture like a load balancer, so it exceeds what this scenario asks for.
When this WOULD be correct
This option would be correct if the question required high availability across datacenter-level failures within a region, such as 'VMs must survive a datacenter outage in the same region' or 'protect against zone-level failures'.
- ✗
Azure Backup
Why it's wrong here
Azure Backup creates recovery points and can restore a VM to a new VM after data loss or a disaster, but it does not keep VMs running during maintenance windows. Maintenance does not destroy data; it reboots or updates the underlying host, and backup cannot prevent that transient downtime. Thus backup is a data-protection recovery tool, not an availability mechanism.
When this WOULD be correct
A question asks: 'You need to ensure VM data is recoverable in case of accidental deletion or corruption. What should you configure?' In that scenario, Azure Backup would be the correct answer.
- ✗
Managed disk
Why it's wrong here
Managed disks offer durable, highly available storage for VM virtual hard disks by replicating data within the storage subsystem, but they do not govern VM placement across maintenance boundaries. The location of a VM on physical hosts is determined by availability sets or zones, not by its disk type. Therefore using managed disks alone leaves a VM vulnerable to downtime when its host undergoes planned maintenance.
When this WOULD be correct
A question asking for a storage solution that provides high availability and fault tolerance for VM disks, such as ensuring data redundancy within a region without requiring VM-level distribution across update domains.
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 logically groups VMs so Azure distributes them across fault domains (isolated power/network) and update domains (host groups rebooted sequentially). During planned host maintenance, Azure updates one update domain at a time, so at least one VM in the set remains online. This is the targeted placement control that directly matches the scenario's requirement.
✗Availability zoneWrong answer — click to see why▾
Why this is wrong here
Availability zones provide datacenter-level redundancy across physically separate zones, which is not required here. The question specifies that datacenter-level redundancy is not needed, and only spreading across update domains within the same region is required, which is a feature of availability sets.
★ When this WOULD be the correct answer
This option would be correct if the question required high availability across datacenter-level failures within a region, such as 'VMs must survive a datacenter outage in the same region' or 'protect against zone-level failures'.
Why candidates choose this
Candidates may confuse availability zones with availability sets, thinking both provide similar fault tolerance, or they may over-engineer the solution by choosing a more redundant option without reading the constraints carefully.
✗Azure BackupWrong answer — click to see why▾
Why this is wrong here
Azure Backup is a data protection service for backing up VMs, not a high-availability feature. It does not distribute VMs across update domains or provide availability during planned host maintenance.
★ When this WOULD be the correct answer
A question asks: 'You need to ensure VM data is recoverable in case of accidental deletion or corruption. What should you configure?' In that scenario, Azure Backup would be the correct answer.
Why candidates choose this
Candidates may confuse backup with high availability, thinking that backing up VMs ensures they stay available during maintenance, or they may misinterpret 'stay available' as 'data is preserved'.
✗Managed diskWrong answer — click to see why▾
Why this is wrong here
Managed disks provide storage redundancy and durability, but they do not distribute VMs across update domains to ensure availability during planned host maintenance.
★ When this WOULD be the correct answer
A question asking for a storage solution that provides high availability and fault tolerance for VM disks, such as ensuring data redundancy within a region without requiring VM-level distribution across update domains.
Why candidates choose this
Candidates may confuse managed disks' built-in replication (e.g., LRS) with the VM-level availability features needed to survive host maintenance events.
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
Dynamic Membership Groups
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.
About these practice questions
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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.