High Availability for VMs Without Availability Zones
An application runs on two identical VMs in a region that does not support availability zones. The app must keep running through planned maintenance and a single hardware fault, and the team does not want to add a second region. Which two deployment choices are appropriate? Select two.
Quick Answer
The answer is a standard virtual machine scale set configured with an availability set, or simply an availability set applied to the two VMs. This works because an availability set distributes VMs across multiple fault domains and update domains within the same datacenter, isolating them from a single hardware fault and from planned maintenance events. Since the region does not support availability zones, this is the only native Azure option to achieve high availability for VMs without availability zones. On the AZ-104 exam, this scenario tests your understanding of regional HA options—specifically that availability sets provide fault and update domain isolation within one datacenter, while availability zones span separate datacenters. A common trap is choosing a proximity placement group, which only reduces latency and does not provide fault tolerance. Remember the mnemonic: “Set for safety, Zones for separation”—when zones are unavailable, an availability set keeps your VMs safe from a single point of failure.
⚠ Common exam trap
The trap here is that candidates might think an availability set is only for legacy scenarios, but it is the correct choice when availability zones are not supported, and a scale set is also valid because it inherently provides fault and update domain isolation without requiring zones.
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
✓
Place the VMs in an availability set.
A is correct because an availability set distributes VMs across multiple fault domains (up to 3) and update domains (up to 20) within the same datacenter. This ensures that during planned maintenance (update domain isolation) or a hardware fault (fault domain isolation), at least one VM remains available, meeting the requirement without needing availability zones or 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.
- ✓
Place the VMs in an availability set.
Why this is correct
An availability set spreads VMs across fault and update domains within the same datacenter scale unit, which protects against planned maintenance and single hardware failures. That matches the region’s lack of zones and the no-second-region requirement.
- ✓
Use a standard virtual machine scale set in the same region.
Why this is correct
A standard VM scale set can spread instances across fault and update domains within a region and can manage multiple identical VMs. It is appropriate when you need platform-managed instance distribution without using availability zones.
- ✗
Put both VMs in the same fault domain to simplify patching.
Why it's wrong here
Placing both VMs in the same fault domain increases correlated failure risk. It defeats the purpose of resilience and would leave the app vulnerable to a single hardware failure.
When this WOULD be correct
If the question asked for a deployment that minimizes maintenance complexity during planned updates and the region does not support availability zones, placing VMs in the same fault domain could simplify patching while still using an availability set to separate update domains.
- ✗
Deploy the workload in availability zones anyway.
Why it's wrong here
The scenario says the region does not support availability zones, so this option is not available. Even if it were, the question requires an answer that works in the stated region.
When this WOULD be correct
If the region supports availability zones and the requirement is to protect against datacenter-level failures, deploying VMs across multiple availability zones would be correct.
- ✗
Use a second Azure region for the primary failover design.
Why it's wrong here
A second region is a disaster recovery pattern, but the scenario explicitly says not to add another region. The question is about in-region resilience only.
When this WOULD be correct
When the question requires high availability across regions to protect against a regional outage, and the team is willing to add a second region, then using a second Azure region for primary failover design (e.g., with Azure Site Recovery or active-passive setup) 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.
✓Place the VMs in an availability set.Correct answer▾
Why this is correct
An availability set spreads VMs across fault and update domains within the same datacenter scale unit, which protects against planned maintenance and single hardware failures. That matches the region’s lack of zones and the no-second-region requirement.
✗Put both VMs in the same fault domain to simplify patching.Wrong answer — click to see why▾
Why this is wrong here
Placing both VMs in the same fault domain defeats the purpose of fault tolerance; a single hardware fault would affect both VMs, causing application downtime. The question requires resilience to a single hardware fault, which necessitates separate fault domains.
★ When this WOULD be the correct answer
If the question asked for a deployment that minimizes maintenance complexity during planned updates and the region does not support availability zones, placing VMs in the same fault domain could simplify patching while still using an availability set to separate update domains.
Why candidates choose this
Candidates may think that keeping VMs in the same fault domain simplifies patching and still provides some protection via update domains, overlooking that fault domains are for hardware fault isolation.
✗Deploy the workload in availability zones anyway.Wrong answer — click to see why▾
Why this is wrong here
The question states the region does not support availability zones, so deploying in availability zones is not possible.
★ When this WOULD be the correct answer
If the region supports availability zones and the requirement is to protect against datacenter-level failures, deploying VMs across multiple availability zones would be correct.
Why candidates choose this
Candidates may assume availability zones are always available or confuse them with availability sets, thinking they provide similar fault isolation without checking regional support.
✗Use a second Azure region for the primary failover design.Wrong answer — click to see why▾
Why this is wrong here
The question explicitly states the team does not want to add a second region, so using a second Azure region for failover contradicts that requirement.
★ When this WOULD be the correct answer
When the question requires high availability across regions to protect against a regional outage, and the team is willing to add a second region, then using a second Azure region for primary failover design (e.g., with Azure Site Recovery or active-passive setup) would be correct.
Why candidates choose this
Candidates may think that using a second region is the only way to achieve high availability, overlooking that availability sets or scale sets within a single region can handle planned maintenance and hardware faults.
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
Azure Virtual Machine Deployment
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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Same concept, more angles
2 more ways 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. An application runs on two VMs in one Azure region. The business wants protection from a single hardware host failure and planned maintenance, but it does not require protection from an entire datacenter outage. Which two choices should the administrator make? Select two.
hard- A.Place the workload in a single VM with a premium SSD.
- ✓ B.Place both VMs in an availability set.
- C.Use availability zones across the region.
- ✓ D.Keep at least two running VMs in that availability set.
- E.Replicate the VMs to another region with Azure Site Recovery.
Why B: An availability set distributes VMs across multiple fault domains (hardware hosts) and update domains within a single Azure datacenter. This protects against a single hardware host failure and planned maintenance (update domains ensure VMs are not rebooted simultaneously during updates). To benefit from this protection, you must have at least two VMs running in the same availability set; a single VM does not receive any fault or update domain isolation. Therefore, Option B (placing both VMs in an availability set) and Option D (keeping at least two running VMs in that availability set) are correct. Availability zones would protect against a full datacenter outage, which is not required here, and Azure Site Recovery is for disaster recovery to another region.
Variation 2. An application uses two Azure VMs in the same datacenter and must continue through planned maintenance and a single hardware host failure. The administrator does not need separate datacenter protection. Which option should be used?
easy- A.Availability zones
- ✓ B.Availability set
- C.Proximity placement group
- D.Virtual machine scale set
Why B: An availability set distributes VMs across multiple fault domains (hardware hosts) and update domains within a single Azure datacenter. This ensures that during planned maintenance (update domains) or a single hardware host failure (fault domains), at least one VM remains available. Since the requirement does not include separate datacenter protection, an availability set is the correct choice.
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.