AZ-104 Deploy and Manage Azure Compute Practice Question
Two legacy application VMs must survive planned maintenance and a single host failure. The vendor requires both VMs to stay in the same region, and a datacenter outage is not part of the requirement. What should the administrator use?
⚠ Common exam trap
Test-takers frequently confuse availability zones (which protect against datacenter outages) with availability sets (which protect against host and rack failures), leading them to choose zones even though the requirement explicitly excludes a datacenter outage.
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
✓
An availability set that places the VMs in separate fault and update domains.
An availability set protects against planned maintenance and single host failures by placing VMs in separate fault domains (different physical hardware) and update domains (different maintenance windows). This ensures that during planned Azure maintenance, only one VM is rebooted at a time, and if a host fails, only VMs in that fault domain are affected. Since the requirement specifies a single host failure (not a datacenter outage) and both VMs must stay in the same region, 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.
- ✓
An availability set that places the VMs in separate fault and update domains.
Why this is correct
Availability sets are designed for host-level resilience inside one datacenter. They spread VMs across fault domains and update domains, which helps reduce impact from hardware failures and planned maintenance. Because the requirement does not include surviving a full datacenter outage, an availability set is the right level of protection without the added complexity of zones.
- ✗
Availability zones with one VM in each zone.
Why it's wrong here
Availability zones are physically separate datacenters within a region, each with independent power, cooling, and networking. While placing one VM in each zone protects against a complete datacenter outage, the scenario only requires surviving planned maintenance and host-level faults within a single datacenter. Using zones introduces unnecessary cross-zone data transfer costs, potential latency, and constraints on VM size availability, making it an over-engineered solution for this legacy workload.
When this WOULD be correct
If the requirement were to survive a full datacenter outage (e.g., due to a regional disaster) while keeping VMs in the same region, then availability zones with one VM in each zone would be correct. For example: 'Two VMs must remain available if an entire datacenter fails, but must stay within the same region.'
- ✗
A virtual machine scale set in a single zone.
Why it's wrong here
A virtual machine scale set in a single zone is designed to run a fleet of identical instances that can scale out and in automatically. For legacy VMs with distinct configurations that are not part of a scaling workload, this is architecturally mismatched. More critically, without explicit zone-spreading or availability-set integration, all instances in a single-zone scale set share the same fault and update domains, meaning planned maintenance can still affect all VMs together.
When this WOULD be correct
An administrator needs to deploy multiple identical VMs that automatically scale based on load, and high availability across zones is not required; a scale set in a single zone provides load balancing and scaling.
- ✗
A proximity placement group for both VMs.
Why it's wrong here
A proximity placement group deliberately co-locates VMs to achieve low network latency, often placing them on the same hardware. This arrangement directly opposes availability goals because co-located VMs share the same fault and update domains, so a single maintenance event or hardware failure can affect both simultaneously. It provides no fault-domain or update-domain separation, so it fails to meet the requirement.
When this WOULD be correct
An administrator needs to minimize network latency between two VMs for a high-performance computing workload, and availability requirements are met by other means (e.g., application-level replication).
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.
✓An availability set that places the VMs in separate fault and update domains.Correct answer▾
Why this is correct
Availability sets are designed for host-level resilience inside one datacenter. They spread VMs across fault domains and update domains, which helps reduce impact from hardware failures and planned maintenance. Because the requirement does not include surviving a full datacenter outage, an availability set is the right level of protection without the added complexity of zones.
✗Availability zones with one VM in each zone.Wrong answer — click to see why▾
Why this is wrong here
The requirement is to survive a single host failure, not a datacenter outage. Availability zones protect against datacenter failures, but placing one VM in each zone would not protect against a single host failure because each zone contains multiple hosts, and the VMs could still be on the same host within a zone.
★ When this WOULD be the correct answer
If the requirement were to survive a full datacenter outage (e.g., due to a regional disaster) while keeping VMs in the same region, then availability zones with one VM in each zone would be correct. For example: 'Two VMs must remain available if an entire datacenter fails, but must stay within the same region.'
Why candidates choose this
Candidates may confuse 'host failure' with 'datacenter failure' and think zones provide high availability for any failure, or they may assume that distributing VMs across zones automatically protects against host failures, not realizing that zones are for datacenter-level redundancy.
✗A virtual machine scale set in a single zone.Wrong answer — click to see why▾
Why this is wrong here
A virtual machine scale set in a single zone does not protect against a single host failure because all VMs could be on the same host; it also doesn't meet the requirement of exactly two legacy VMs with separate fault domains.
★ When this WOULD be the correct answer
An administrator needs to deploy multiple identical VMs that automatically scale based on load, and high availability across zones is not required; a scale set in a single zone provides load balancing and scaling.
Why candidates choose this
Candidates may think a scale set inherently provides high availability, but without multiple zones or fault domains, it doesn't protect against host failures.
✗A proximity placement group for both VMs.Wrong answer — click to see why▾
Why this is wrong here
A proximity placement group ensures low network latency between VMs but does not protect against planned maintenance or single host failure, as VMs can still be placed on the same host or fault domain.
★ When this WOULD be the correct answer
An administrator needs to minimize network latency between two VMs for a high-performance computing workload, and availability requirements are met by other means (e.g., application-level replication).
Why candidates choose this
Candidates may confuse proximity placement groups with high availability solutions, thinking that placing VMs close together somehow provides redundancy.
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
Fault domain
A fault domain is a boundary within a computing environment that groups together components that share a single point of failure, helping to isolate the impact of hardware or software failures.
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.
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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.