AZ-104 Deploy and Manage Azure Compute Practice Question
A customer-facing application has two goals: it must keep running if one datacenter in the region fails, and it must be able to scale out automatically during daily peaks. Which two Azure compute choices best match those requirements? Select two.
⚠ Common exam trap
Candidates often confuse Availability Sets (which protect against rack failures) with Availability Zones (which protect against datacenter failures), and they may overlook that a single VM behind a load balancer still has a single point of failure.
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
✓
Deploy the workload across Availability Zones
Deploying across Availability Zones provides datacenter-level fault tolerance: each zone is an isolated physical datacenter with independent power, cooling, and networking. If one zone fails, the application continues running in the other zones. Option C is correct because a Virtual Machine Scale Set with autoscale automatically adjusts the number of VM instances based on CPU or memory metrics, enabling the application to scale out during daily peaks and scale in during off-peak hours.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Deploy the workload across Availability Zones
Why this is correct
Deploying the workload across Availability Zones is correct because each zone is an isolated datacenter with independent power, cooling, and networking. If one zone fails, the other zones continue serving traffic, eliminating a single datacenter as a point of failure. Azure offers a 99.99% availability SLA when instances are distributed across two or more zones, directly supporting the goal of keeping the application running during an outage.
- ✗
Place all instances in one Availability Set
Why it's wrong here
Placing all instances in one Availability Set is wrong because an availability set distributes VMs across fault domains and update domains only within a single datacenter. It protects against rack-level failures and planned maintenance, but it cannot survive a full datacenter outage—if the entire datacenter goes down, every instance in the set is lost. The goal requires surviving a datacenter-level failure, so an availability set alone is insufficient.
When this WOULD be correct
If the question required high availability for a workload within a single datacenter (e.g., protecting against hardware failures) and did not require cross-datacenter resilience or autoscaling, placing VMs in an Availability Set would be correct.
- ✓
Use a Virtual Machine Scale Set with autoscale
Why this is correct
Using a Virtual Machine Scale Set with autoscale is correct as a complementary availability mechanism because it automatically adds or removes identical instances based on demand or a schedule. Autoscaling prevents overload during traffic spikes and can replace unhealthy instances if health probes are configured, but it does not inherently protect against a zonal failure unless the scale set spans multiple zones. Still, it helps maintain capacity and responsiveness, which supports continuous operation.
- ✗
Run a single VM behind a load balancer
Why it's wrong here
Running a single VM behind a load balancer is wrong because the load balancer has only one backend target, making that VM a single point of failure. If the VM fails or becomes unhealthy, the load balancer has no other instance to route traffic to, so the application goes down. A load balancer provides distribution and health-based routing, but it cannot offer failover without at least two redundant VM instances.
When this WOULD be correct
If the question asked for a cost-effective solution for a low-traffic application that requires high availability within a single datacenter (e.g., during planned maintenance), running a single VM behind a load balancer with an Availability Set would be correct.
- ✗
Use a proximity placement group
Why it's wrong here
Using a proximity placement group is wrong because it deliberately co-locates VMs in the same Azure datacenter or rack to minimize network latency. This co-location increases the blast radius: if that datacenter experiences an outage, all VMs in the group fail together. A proximity placement group is a performance optimization, not a resilience mechanism, and can actually reduce availability by making workloads more susceptible to correlated failures.
When this WOULD be correct
For a latency-sensitive application (e.g., high-performance computing) where all VMs must be in close proximity to minimize network latency, and the question does not require fault tolerance across datacenters or autoscaling.
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.
✓Deploy the workload across Availability ZonesCorrect answer▾
Why this is correct
Deploying the workload across Availability Zones is correct because each zone is an isolated datacenter with independent power, cooling, and networking. If one zone fails, the other zones continue serving traffic, eliminating a single datacenter as a point of failure. Azure offers a 99.99% availability SLA when instances are distributed across two or more zones, directly supporting the goal of keeping the application running during an outage.
✗Place all instances in one Availability SetWrong answer — click to see why▾
Why this is wrong here
An Availability Set only protects against rack-level failures within a single datacenter, not against a full datacenter outage. It also does not provide automatic scaling.
★ When this WOULD be the correct answer
If the question required high availability for a workload within a single datacenter (e.g., protecting against hardware failures) and did not require cross-datacenter resilience or autoscaling, placing VMs in an Availability Set would be correct.
Why candidates choose this
Candidates may confuse Availability Sets with Availability Zones, thinking both provide datacenter-level fault tolerance, or they may overlook the requirement for automatic scaling.
✗Run a single VM behind a load balancerWrong answer — click to see why▾
Why this is wrong here
A single VM cannot survive a datacenter failure because it is a single point of failure, and it cannot scale out automatically since scaling requires multiple instances.
★ When this WOULD be the correct answer
If the question asked for a cost-effective solution for a low-traffic application that requires high availability within a single datacenter (e.g., during planned maintenance), running a single VM behind a load balancer with an Availability Set would be correct.
Why candidates choose this
Candidates may think a load balancer provides automatic failover and scaling, but a load balancer alone does not create redundancy or autoscaling without multiple VMs.
✗Use a proximity placement groupWrong answer — click to see why▾
Why this is wrong here
A proximity placement group reduces network latency between VMs but does not provide datacenter failure resilience or automatic scaling, which are the two key requirements.
★ When this WOULD be the correct answer
For a latency-sensitive application (e.g., high-performance computing) where all VMs must be in close proximity to minimize network latency, and the question does not require fault tolerance across datacenters or autoscaling.
Why candidates choose this
Candidates may confuse proximity placement groups with high availability features, thinking that grouping VMs together ensures resilience, or they may overemphasize low latency without considering the explicit requirements for fault tolerance and scaling.
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.
About these practice questions
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Same concept, more angles
1 more way this is tested on AZ-104
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A stateless application must keep serving traffic if one datacenter in the region fails, and it must also add or remove instances during daily load spikes. Which two deployment choices should the administrator make? Select two.
hard- ✓ A.Deploy the application on a virtual machine scale set.
- ✓ B.Configure the deployment to use availability zones.
- C.Use a single availability set with one VM to reduce complexity.
- D.Use a proximity placement group for the workload.
- E.Deploy one larger VM with a premium SSD instead of multiple instances.
Why A: A virtual machine scale set (VMSS) allows automatic scaling of instances in response to load spikes, meeting the requirement to add or remove instances dynamically. Combined with availability zones, which distribute instances across physically separate datacenters within a region, the application remains available even if one entire datacenter fails. This pair ensures both high availability and elastic scaling for a stateless application.
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.