AZ-104 Deploy and Manage Azure Compute Practice Question
A line-of-business web tier consists of two Azure VMs in a region that supports availability zones. The business requirement is to survive a full datacenter outage in that region without deploying to a second region. What should the administrator use?
⚠ Common exam trap
It's easy for candidates to confuse availability sets (which protect within a datacenter) with availability zones (which protect across datacenters), leading them to choose an availability set despite the explicit requirement to survive a full 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
✓
Availability zones with the VMs placed in different zones
Availability zones are physically separate datacenters within an Azure region, each with independent power, cooling, and networking. Placing the two VMs in different zones ensures that if one entire datacenter fails, the other VM remains operational, meeting the requirement to survive a full datacenter outage without deploying to a second region.
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 with multiple update domains
Why it's wrong here
An availability set provides fault domain and update domain isolation, but both domains operate within a single datacenter (for managed disks, each fault domain maps to a different rack within the same datacenter). This protects against hardware failures like a failed host or power supply, and against planned Azure maintenance windows, but it cannot survive a complete datacenter failure. The requirement here is to tolerate an entire datacenter becoming unavailable, which is beyond what an availability set can handle.
When this WOULD be correct
An availability set would be correct if the requirement was to protect against hardware failures within a single datacenter (e.g., server rack or network switch failure) while keeping VMs in the same datacenter for low latency, and the region does not support availability zones.
- ✓
Availability zones with the VMs placed in different zones
Why this is correct
Availability zones are physically separate datacenter locations within an Azure region, each with independent power, cooling, and networking. By placing the two VMs in different zones, you eliminate a single-datacenter dependency, so if one zone experiences an outage (e.g., a regional storm or cooling failure), the other VM remains online. This is the only option listed that provides true datacenter-level fault isolation while keeping both VMs in the same region for low-latency traffic.
- ✗
A proximity placement group for both VMs
Why it's wrong here
A proximity placement group (PPG) only co-locates VMs to reduce network latency by placing them in the same Azure datacenter or at least in close physical proximity. It does not distribute workloads across fault domains or availability zones, so if that single datacenter fails, both VMs go down together. PPGs are designed for performance-sensitive, tightly coupled workloads requiring low inter-VM latency, not for high availability against datacenter-wide outages.
When this WOULD be correct
An administrator needs to minimize network latency between two VMs for a high-performance computing workload, and the VMs must be in the same region but as close as possible.
- ✗
A single-zone virtual machine scale set
Why it's wrong here
A single-zone virtual machine scale set deploys all VM instances within one availability zone, meaning the entire scale set resides in a single physical datacenter. If that zone suffers an outage, all instances in the scale set fail simultaneously, violating the stated requirement. While scale sets offer auto-scaling and VM distribution across fault domains within the zone, they do not provide cross-zone redundancy unless you explicitly create instances in multiple zones (a zone-redundant scale set).
When this WOULD be correct
If the requirement were to achieve high availability within a single datacenter (e.g., to protect against server or rack failures) without needing to survive a full datacenter outage, a single-zone VMSS with multiple instances would be correct.
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 zones with the VMs placed in different zonesCorrect answer▾
Why this is correct
Availability zones are physically separate datacenter locations within an Azure region, each with independent power, cooling, and networking. By placing the two VMs in different zones, you eliminate a single-datacenter dependency, so if one zone experiences an outage (e.g., a regional storm or cooling failure), the other VM remains online. This is the only option listed that provides true datacenter-level fault isolation while keeping both VMs in the same region for low-latency traffic.
✗An availability set with multiple update domainsWrong answer — click to see why▾
Why this is wrong here
An availability set protects against rack-level failures within a single datacenter, not against a full datacenter outage. The requirement to survive a full datacenter outage demands distribution across availability zones, which are physically separate datacenters within a region.
★ When this WOULD be the correct answer
An availability set would be correct if the requirement was to protect against hardware failures within a single datacenter (e.g., server rack or network switch failure) while keeping VMs in the same datacenter for low latency, and the region does not support availability zones.
Why candidates choose this
Candidates may confuse update domains with fault domains or assume that multiple update domains provide datacenter-level redundancy, not realizing that availability sets only span a single datacenter.
✗A proximity placement group for both VMsWrong answer — click to see why▾
Why this is wrong here
A proximity placement group reduces network latency between VMs but does not protect against a full datacenter outage because all VMs in the group could be in the same datacenter.
★ When this WOULD be the correct answer
An administrator needs to minimize network latency between two VMs for a high-performance computing workload, and the VMs must be in the same region but as close as possible.
Why candidates choose this
Candidates may confuse proximity placement groups with high availability features, thinking that placing VMs close together ensures they are in different failure domains.
✗A single-zone virtual machine scale setWrong answer — click to see why▾
Why this is wrong here
A single-zone VMSS places all VMs in the same availability zone, which cannot survive a full datacenter outage because that zone is tied to a single datacenter.
★ When this WOULD be the correct answer
If the requirement were to achieve high availability within a single datacenter (e.g., to protect against server or rack failures) without needing to survive a full datacenter outage, a single-zone VMSS with multiple instances would be correct.
Why candidates choose this
Candidates may think VMSS inherently provides high availability across zones, but a single-zone VMSS only distributes across fault domains within one zone, not across zones.
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
Availability is the measure of how often a system or service is operational and accessible when needed, typically expressed as a percentage of uptime.
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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.