Azure Virtual Machines are the correct choice because they provide full OS control and support for custom kernel modules, which is exactly what you need when migrating legacy applications that require deep system-level customization. Unlike platform-as-a-service options that abstract away the operating system, Azure VMs give you complete administrative access to install, configure, and load custom kernel modules, while also enabling high availability through availability sets or availability zones that distribute multiple instances across fault domains. On the AZ-900 exam, this question tests your understanding of the core difference between Infrastructure-as-a-Service (IaaS) and higher-level services like App Service or Containers—a common trap is choosing App Service because it’s simpler, but it lacks OS-level access. Remember the memory tip: if the app needs to “touch the kernel,” you need a Virtual Machine.
AZ-900 Describe Azure architecture and services Practice Question
This AZ-900 practice question tests your understanding of describe azure architecture and services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company needs to run a legacy application that requires full control over the operating system, including custom kernel modules. They also need to ensure high availability with multiple instances. Which Azure compute service should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Virtual Machines
Azure Virtual Machines (VMs) are the correct choice because they provide full control over the operating system, including the ability to install custom kernel modules, and support high availability through availability sets or zones. This is essential for legacy applications that require OS-level customization and fault-tolerant deployment.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Azure App Service
Why it's wrong here
App Service is a PaaS offering where you have no control over the OS or kernel.
✗
Azure Functions
Why it's wrong here
Functions are serverless and abstract away the underlying infrastructure entirely.
✓
Azure Virtual Machines
Why this is correct
Correct. VMs offer full OS control and can be deployed in high availability configurations.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Container Instances
Why it's wrong here
Container Instances run containers that share the host OS kernel; you do not have control over the underlying OS.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse Azure App Service or Container Instances as suitable for legacy apps, but those services lack the necessary OS-level access and kernel module support that only IaaS like Virtual Machines provides.
Detailed technical explanation
How to think about this question
Azure VMs run on hypervisor-isolated hardware, giving the guest OS full access to the kernel space, enabling custom kernel modules (e.g., loadable kernel modules in Linux via `insmod`). High availability is achieved by deploying VMs across availability sets (fault and update domains) or availability zones (physically separate datacenters), ensuring at least 99.95% SLA. In contrast, PaaS and serverless services restrict OS access to maintain multi-tenancy and automatic patching.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Azure Virtual Machines — Azure Virtual Machines (VMs) are the correct choice because they provide full control over the operating system, including the ability to install custom kernel modules, and support high availability through availability sets or zones. This is essential for legacy applications that require OS-level customization and fault-tolerant deployment.
What should I do if I get this AZ-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This AZ-900 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-900 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.