Question 562 of 981
Who Patches the OS? Shared Responsibility in Azure
A company migrates its on-premises SQL Server database to Azure SQL Database. The company's security team is concerned about who is responsible for applying security updates to the operating system that hosts the database engine. According to the shared responsibility model for cloud computing, who is responsible for patching the operating system of the underlying host?
Quick Answer
The answer is Microsoft, because Azure SQL Database is a Platform as a Service (PaaS) offering where the cloud provider manages the underlying host operating system. In the shared responsibility model for OS patching, responsibility shifts from the customer to Microsoft as you move from Infrastructure as a Service (IaaS) to PaaS; with Azure SQL Database, Microsoft handles all hypervisor, host OS, and physical infrastructure updates, while the customer only manages data, access, and database-level configurations. On the AZ-900 exam, this question tests your understanding of how the shared responsibility model applies to different service models—a common trap is assuming the customer must patch the OS for any database service, but PaaS services like Azure SQL Database transfer that duty to Azure. Remember the memory tip: “PaaS patches the platform, IaaS is on you”—if you see a managed database service, the provider owns the OS patches.
⚠ Common exam trap
Many exam-takers confuse IaaS (where the customer patches the OS) with PaaS (where Microsoft patches the OS), leading them to incorrectly select the customer or shared responsibility options.
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
✓
Microsoft (Azure)
In the shared responsibility model for Azure SQL Database, Microsoft is responsible for the underlying infrastructure, including the operating system that hosts the database engine. Azure SQL Database is a Platform as a Service (PaaS) offering, where Microsoft manages the host OS, applies security patches, and ensures the physical and virtual environment is secure. The customer is only responsible for data, access management, and database-level configurations.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The company (customer)
Why it's wrong here
This choice is incorrect because in a PaaS service like Azure SQL Database, the customer does not have administrative access to the underlying operating system and therefore cannot patch it. The customer's responsibility includes securing the database itself (e.g., authentication, encryption at rest/transit), but not OS-level maintenance.
When this WOULD be correct
If the question asked about patching the operating system of a virtual machine running SQL Server on an Azure VM (IaaS), the customer would be responsible for applying OS updates.
- ✓
Microsoft (Azure)
Why this is correct
This choice is correct because Azure SQL Database is a PaaS offering. Microsoft is responsible for managing the host operating system, including applying security updates, patching, and maintaining the infrastructure. The customer only interacts with the database instance at the logical level.
- ✗
Both the company and Microsoft share this responsibility
Why it's wrong here
This choice is incorrect because the responsibility for OS patching is not shared. The provider handles the host OS; the customer handles the data and database access. Shared responsibility applies to other areas, such as network controls, but not to patching the underlying OS in PaaS.
When this WOULD be correct
This option would be correct if the question described a scenario where the customer manages a virtual machine (IaaS) running SQL Server, such as an Azure VM with SQL Server installed, where both the customer and Microsoft share responsibility for patching the OS and SQL Server respectively.
- ✗
A third-party managed service provider
Why it's wrong here
This choice is incorrect because Azure SQL Database is a first-party Microsoft service. There is no third-party vendor involved in managing the infrastructure. If the customer hired a third party to manage their Azure resources, that vendor might assist with configuration, but they would still rely on Microsoft for OS patching.
When this WOULD be correct
This option would be correct if the question described a scenario where the company hires a third-party provider to manage a self-hosted SQL Server on an IaaS VM, and the provider is contractually responsible for OS patching.
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-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Microsoft (Azure)Correct answer▾
Why this is correct
This choice is correct because Azure SQL Database is a PaaS offering. Microsoft is responsible for managing the host operating system, including applying security updates, patching, and maintaining the infrastructure. The customer only interacts with the database instance at the logical level.
✗The company (customer)Wrong answer — click to see why▾
Why this is wrong here
In Azure SQL Database, Microsoft manages the underlying operating system, including patching, as part of the Platform as a Service (PaaS) model. The customer is only responsible for data and access management, not OS patching.
★ When this WOULD be the correct answer
If the question asked about patching the operating system of a virtual machine running SQL Server on an Azure VM (IaaS), the customer would be responsible for applying OS updates.
Why candidates choose this
Candidates may confuse PaaS with IaaS, assuming that because they manage the database, they also manage the underlying OS, or they may overgeneralize on-premises responsibilities to the cloud.
✗Both the company and Microsoft share this responsibilityWrong answer — click to see why▾
Why this is wrong here
In Azure SQL Database, the operating system hosting the database engine is managed by Microsoft as part of the Platform as a Service (PaaS) model. The customer is responsible only for data and access management, not OS patching.
★ When this WOULD be the correct answer
This option would be correct if the question described a scenario where the customer manages a virtual machine (IaaS) running SQL Server, such as an Azure VM with SQL Server installed, where both the customer and Microsoft share responsibility for patching the OS and SQL Server respectively.
Why candidates choose this
Candidates may mistakenly think that security updates are always a shared responsibility in the cloud, not realizing that in PaaS services like Azure SQL Database, Microsoft handles the underlying infrastructure patching entirely.
✗A third-party managed service providerWrong answer — click to see why▾
Why this is wrong here
Azure SQL Database is a PaaS service where Microsoft manages the underlying OS, including patching. A third-party managed service provider is not involved unless explicitly contracted, which is not the case here.
★ When this WOULD be the correct answer
This option would be correct if the question described a scenario where the company hires a third-party provider to manage a self-hosted SQL Server on an IaaS VM, and the provider is contractually responsible for OS patching.
Why candidates choose this
Candidates may confuse Azure SQL Database (PaaS) with a managed service that could be outsourced, or they might think a third-party is always needed for security updates.
Analysis generated from the official AZ-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Same concept, more angles
1 more way this is tested on AZ-900
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 company runs its production database on an Azure SQL Database (PaaS) and its custom application on an Azure virtual machine (IaaS). The company needs to ensure that operating system security patches are applied. According to the shared responsibility model, which resource requires the company to apply OS patches?
medium- A.Azure SQL Database only
- ✓ B.Azure virtual machine only
- C.Both Azure SQL Database and the virtual machine
- D.Neither resource requires the company to apply OS patches
Why B: In the shared responsibility model, the customer is responsible for securing the operating system on IaaS resources like Azure virtual machines. Azure SQL Database is a PaaS service where Microsoft manages the underlying OS, including patch management. Therefore, only the Azure virtual machine requires the company to apply OS security patches.
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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