AZ-900 Describe Azure architecture and services Practice Question
A company is migrating a customer-facing web application to Azure. The application requires a relational database with built-in high availability, automatic backups, and automatic patching of the database engine. The development team is familiar with SQL Server and wants to minimize administrative overhead. They do not want to manage virtual machines or operating systems. Which Azure database service should the team choose?
⚠ Common exam trap
It's easy for candidates to confuse Azure Cosmos DB's 'multi-model' support with relational database capabilities, or they assume IaaS gives more control without realizing the significant administrative overhead it entails, especially when the question explicitly states 'minimize administrative overhead' and 'do not want to manage virtual machines'.
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
✓
Azure SQL Database (PaaS)
Azure SQL Database is a fully managed Platform-as-a-Service (PaaS) offering that provides built-in high availability (99.99% SLA), automatic backups with point-in-time restore, and automatic patching of the database engine. It allows the development team to use their existing SQL Server skills without managing any virtual machines or operating systems, directly meeting the requirement to minimize administrative overhead.
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 Cosmos DB
Why it's wrong here
Azure Cosmos DB is a globally distributed, multi-model NoSQL database service. It does not natively support SQL Server relational queries (like JOINs) and is designed for non-relational (NoSQL) workloads. Thus, it is not the correct choice for a relational SQL Server-based application.
When this WOULD be correct
A company needs a globally distributed, multi-model database with low latency and flexible schema for a real-time application that handles large volumes of unstructured data, such as a global IoT telemetry system or a social media feed.
- ✗
SQL Server on Azure Virtual Machines (IaaS)
Why it's wrong here
SQL Server on Azure VMs is an infrastructure-as-a-service (IaaS) offering. While it provides full control over the SQL Server environment, it requires the team to manage the virtual machines, operating system patches, and SQL Server updates. This does not meet the requirement to minimize administrative overhead.
When this WOULD be correct
A company needs full control over the SQL Server configuration, including custom patching schedules, specific SQL Server versions, or third-party software on the same VM, and is willing to manage the underlying OS and VM.
- ✓
Azure SQL Database (PaaS)
Why this is correct
Azure SQL Database is a platform-as-a-service (PaaS) relational database service based on SQL Server. It includes built-in high availability, automatic backups, and automatic patching of the database engine. The team does not need to manage any virtual machines or operating systems, which aligns perfectly with their goal of minimizing administrative overhead.
- ✗
Azure Database for PostgreSQL
Why it's wrong here
Azure Database for PostgreSQL is a managed relational database service, but it uses the PostgreSQL engine, not SQL Server. While it also provides high availability and automatic backups, it does not support the SQL Server dialect or features the development team is familiar with. The requirement states familiarity with SQL Server, so this is not the correct service.
When this WOULD be correct
A company is migrating an application that uses PostgreSQL and requires a fully managed database service with built-in high availability, automatic backups, and automatic patching, and the team has PostgreSQL expertise. They want to avoid managing virtual machines.
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.
✓Azure SQL Database (PaaS)Correct answer▾
Why this is correct
Azure SQL Database is a platform-as-a-service (PaaS) relational database service based on SQL Server. It includes built-in high availability, automatic backups, and automatic patching of the database engine. The team does not need to manage any virtual machines or operating systems, which aligns perfectly with their goal of minimizing administrative overhead.
✗Azure Cosmos DBWrong answer — click to see why▾
Why this is wrong here
Azure Cosmos DB is a NoSQL database, not a relational database, and does not support SQL Server compatibility or relational querying as required by the question.
★ When this WOULD be the correct answer
A company needs a globally distributed, multi-model database with low latency and flexible schema for a real-time application that handles large volumes of unstructured data, such as a global IoT telemetry system or a social media feed.
Why candidates choose this
Candidates may confuse Cosmos DB's support for SQL API with being a relational database, or assume its high availability and automatic features make it suitable for any database need.
✗SQL Server on Azure Virtual Machines (IaaS)Wrong answer — click to see why▾
Why this is wrong here
SQL Server on Azure VMs (IaaS) requires managing virtual machines and operating systems, which contradicts the requirement to minimize administrative overhead and avoid managing VMs or OS.
★ When this WOULD be the correct answer
A company needs full control over the SQL Server configuration, including custom patching schedules, specific SQL Server versions, or third-party software on the same VM, and is willing to manage the underlying OS and VM.
Why candidates choose this
Candidates may think that because the team is familiar with SQL Server, running it on a VM gives them the most control and familiarity, overlooking the administrative overhead and the requirement for a managed service.
✗Azure Database for PostgreSQLWrong answer — click to see why▾
Why this is wrong here
The question specifies that the team is familiar with SQL Server and wants to minimize administrative overhead with built-in high availability, automatic backups, and patching. Azure Database for PostgreSQL is a different database engine (PostgreSQL) and does not align with the team's SQL Server expertise.
★ When this WOULD be the correct answer
A company is migrating an application that uses PostgreSQL and requires a fully managed database service with built-in high availability, automatic backups, and automatic patching, and the team has PostgreSQL expertise. They want to avoid managing virtual machines.
Why candidates choose this
Candidates may confuse Azure Database for PostgreSQL as a PaaS option similar to Azure SQL Database, or they may not carefully read the requirement for SQL Server familiarity.
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?”
Go deeper
Related to this question
Learn chapter
Azure Regions and Geographies
Key term
SLA
A Service Level Agreement (SLA) is a contract between a service provider and a customer that defines the level of service expected, including metrics like uptime, response time, and penalties for non-compliance.
Key term
PaaS
Platform as a Service (PaaS) is a cloud computing model that provides a managed platform for developers to build, run, and manage applications without dealing with the underlying infrastructure.
About these practice questions
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.