- A
Microsoft is responsible for maintaining and patching the guest operating system on Azure virtual machines.
Why wrong: This is incorrect. For Azure virtual machines (IaaS), Microsoft manages only the physical host, hypervisor, and Azure networking. The customer manages the guest OS, including patching and security.
- B
The customer is responsible for maintaining and patching the guest operating system on Azure virtual machines.
This is correct. Under the shared responsibility model for IaaS, the customer has full control over the guest OS, applications, and data, and is therefore responsible for patching and securing the OS.
- C
Microsoft is responsible for patching any application software that runs on Azure virtual machines.
Why wrong: This is incorrect. Application software is the customer's responsibility regardless of the deployment model. Microsoft does not patch customer-installed applications on IaaS VMs.
- D
The customer is responsible for the physical security of the Azure datacenter where the virtual machines are hosted.
Why wrong: This is incorrect. Physical security of Azure datacenters, including access controls, surveillance, and environmental controls, is solely Microsoft's responsibility under the shared responsibility model.
AZ-900 Describe cloud concepts Practice Question
This AZ-900 practice question tests your understanding of describe cloud concepts. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 migrates its on-premises servers to Azure virtual machines (IaaS model). The security team is planning the patching strategy and asks who is responsible for installing security updates on the guest operating system of the Azure VMs. According to the shared responsibility model, which statement is correct?
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
The customer is responsible for maintaining and patching the guest operating system on Azure virtual machines.
In the shared responsibility model for IaaS, the customer retains control over the guest operating system, applications, and data. Microsoft manages the physical host, hypervisor, and underlying Azure infrastructure, but the customer must install and maintain security updates on the guest OS of their Azure VMs. This is because the customer has full administrative access to the VM and is responsible for its configuration and patch management.
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.
- ✗
Microsoft is responsible for maintaining and patching the guest operating system on Azure virtual machines.
Why it's wrong here
This is incorrect. For Azure virtual machines (IaaS), Microsoft manages only the physical host, hypervisor, and Azure networking. The customer manages the guest OS, including patching and security.
- ✓
The customer is responsible for maintaining and patching the guest operating system on Azure virtual machines.
Why this is correct
This is correct. Under the shared responsibility model for IaaS, the customer has full control over the guest OS, applications, and data, and is therefore responsible for patching and securing the OS.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Microsoft is responsible for patching any application software that runs on Azure virtual machines.
Why it's wrong here
This is incorrect. Application software is the customer's responsibility regardless of the deployment model. Microsoft does not patch customer-installed applications on IaaS VMs.
- ✗
The customer is responsible for the physical security of the Azure datacenter where the virtual machines are hosted.
Why it's wrong here
This is incorrect. Physical security of Azure datacenters, including access controls, surveillance, and environmental controls, is solely Microsoft's responsibility under the shared responsibility model.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse IaaS with PaaS or SaaS, where Microsoft does manage the guest OS (e.g., Azure App Service or SQL Database), leading them to incorrectly assume Microsoft handles patching for Azure VMs.
Detailed technical explanation
How to think about this question
Under the hood, Azure VMs run on Hyper-V hosts where Microsoft patches the hypervisor and host OS automatically, but the guest OS (e.g., Windows Server or Linux) is a separate instance managed by the customer. In practice, customers often use Azure Update Manager, Azure Automation Update Management, or third-party tools to schedule and apply patches, but the responsibility for initiating and verifying those updates remains with the customer. A common real-world scenario is a customer failing to patch a critical vulnerability in the guest OS, leading to a breach that Microsoft explicitly states is the customer's liability under the shared responsibility model.
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
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this AZ-900 question test?
Describe cloud concepts — This question tests Describe cloud concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The customer is responsible for maintaining and patching the guest operating system on Azure virtual machines. — In the shared responsibility model for IaaS, the customer retains control over the guest operating system, applications, and data. Microsoft manages the physical host, hypervisor, and underlying Azure infrastructure, but the customer must install and maintain security updates on the guest OS of their Azure VMs. This is because the customer has full administrative access to the VM and is responsible for its configuration and patch management.
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
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Last reviewed: Jun 11, 2026
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.
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