Azure database services: SQL, Cosmos DB and more

The managed-database family the AZ-900 loves to test — the Azure SQL ladder, Cosmos DB for NoSQL, and managed MySQL and PostgreSQL — with the trade-offs pinned down. AZ-900, 2026 edition.

Here are 7 typical Azure-database questions in the exam's own style — free, each answer explained, no sign-up.

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Azure gives you a whole family of database services, and the AZ-900 tests whether you can match a scenario to the right one. The trick is that most of these are managed — Microsoft runs the operating system, the patching, the backups, and the high availability — so you compare them on what engine and how much control rather than who keeps the lights on. The diagram above sorts the family into three columns: relational (the SQL ladder), non-relational (Cosmos DB), and the managed open-source engines. Learn those three groups and this cluster of questions turns into free points.

The Azure SQL ladder: managed to self-managed

For relational, SQL Server-style workloads there is a ladder from fully managed to fully self-managed. It shows up on the exam again and again:

Azure SQL Database — the top rung, fully managed PaaS. Microsoft owns the OS, patching, backups, and built-in high availability. You touch only the database. Least control, least administration.
Azure SQL Managed Instance — the middle rung. Still managed, but with near-100% SQL Server compatibility and instance-level features such as SQL Server Agent and cross-database queries. Built for lift-and-shift migrations of existing SQL Server databases.
SQL Server on an Azure VM — the bottom rung, IaaS. You choose the exact SQL Server build, control the operating system, and install what you like — and in return you own patching, backups, and availability. Most control, most admin.

Read the ladder either way: step up for less administration, step down for more control. That single mental picture answers most of the SQL questions the exam throws at you.

Cosmos DB: managed NoSQL, built to go global

When the data is non-relational — documents, key-value, graph — the answer is Azure Cosmos DB. It is a globally distributed, multi-model, fully managed NoSQL database designed for low, predictable latency (single-digit milliseconds) at scale. Its signature feature is turnkey global distribution: you add a region with a setting, not a rebuild. If a scenario mentions NoSQL, multi-model data, or replicating worldwide with a switch, Cosmos DB is almost always the intended answer.

Managed open-source: MySQL and PostgreSQL

Not every app speaks SQL Server. For teams already running the popular open-source engines, Azure offers Azure Database for MySQL and Azure Database for PostgreSQL — managed PaaS versions of those engines. You keep your existing engine and application, and Microsoft takes over patching, backups, and availability. The exam cue is simple: “we already use MySQL/PostgreSQL and want it managed without changing engines.”

Managed (PaaS) vs a database on a VM

The through-line for all of it: a managed database means Microsoft handles the operational plumbing so your team spends less time on server administration. A database you install on a VM is IaaS — maximum control, but you administer it end to end. Managed is not automatically cheaper, and it does not design your schema or write your queries for you; it removes the server toil, not the data work. Keep that distinction straight and the trade-off questions resolve themselves.

The real exam mixes multiple-choice, true/false, and drag-and-drop formats; the seven questions below are standard multiple-choice, and every explanation carries a “why not the others” so the wrong options teach you as much as the right one.

A three-column map of Microsoft Azure's managed database services. The left column, headed Relational (SQL), shows a ladder of three rungs from most managed to most control: Azure SQL Database, a fully managed PaaS database engine; Azure SQL Managed Instance, near-full SQL Server compatibility with instance-level features, still managed; and SQL Server on an Azure VM, an IaaS option where you run and patch the operating system and the SQL Server software yourself. An arrow beside the ladder is labelled more control, more admin work going down and less admin, fully managed going up. The middle column, headed Non-relational (NoSQL), shows Azure Cosmos DB, described as a globally distributed, multi-model, low-latency managed NoSQL service with turnkey global distribution. The right column, headed Open-source engines, shows Azure Database for MySQL and Azure Database for PostgreSQL, both managed PaaS versions of the popular open-source engines. A caption underneath reads: managed (PaaS) means Microsoft runs the OS, patching, and backups; a database you install on a VM (IaaS) is yours to administer.

7 free AZ-900 practice questions

Answers and explanations — no email wall

AZ-900 Question 1 of 7

A team is building a new line-of-business app on a relational schema. They want Microsoft to handle patching, automated backups, and built-in high availability, and they never want to sign in to the host operating system. They do not need instance-scoped features such as SQL Server Agent or cross-database queries. Which service is the best fit?

Answer: A — Azure SQL Database.

Azure SQL Database is the fully managed PaaS relational engine: Microsoft runs the operating system, patching, backups, and high availability, and you interact only with the database itself. That matches every requirement here. Why not the others: SQL Managed Instance is also managed but exists precisely to add the instance-level features (SQL Agent, cross-database queries) this team says it does not need, so it is more than required. SQL Server on a VM is IaaS — you would own the OS and patching, the opposite of the ask. Cosmos DB is a NoSQL service, not a relational schema. Pro tip: fully managed + relational + no OS access + no instance-level features points straight at Azure SQL Database.

AZ-900 Question 2 of 7

A company is lifting an existing on-premises SQL Server database into Azure. The application relies on instance-scoped features — SQL Server Agent jobs and cross-database queries — so it needs near-full SQL Server compatibility, but the team still wants a managed service rather than administering a server. Which option matches?

Answer: A — Azure SQL Managed Instance.

Azure SQL Managed Instance is the middle rung of the SQL ladder: it delivers near-100% compatibility with the SQL Server engine, including instance-level features such as SQL Server Agent and cross-database queries, while Microsoft still manages patching and backups — ideal for lift-and-shift migrations. Why not the others: plain Azure SQL Database is single-database PaaS and does not expose those instance-scoped features. SQL Server on a VM would give compatibility but hands you the whole OS and software to administer, which the team wants to avoid. Azure Database for PostgreSQL is a different engine entirely. Pro tip: 'lift-and-shift SQL Server + instance-level features + still managed' is the signature of SQL Managed Instance.

AZ-900 Question 3 of 7

A workload needs a specific build of SQL Server, full administrative access to the operating system, and the ability to install third-party agents on the same host. Which Azure option provides that level of control?

Answer: A — SQL Server running on an Azure virtual machine.

Running SQL Server on an Azure virtual machine is the IaaS end of the ladder: you control the OS, choose the exact SQL Server version, and can install anything on the host — in exchange for owning patching, backups, and availability yourself. That maximum-control requirement is what points here. Why not the others: Azure SQL Database and SQL Managed Instance are managed PaaS, so Microsoft owns the OS and you cannot install host-level software. Cosmos DB is a managed NoSQL service and is not SQL Server at all. Pro tip: 'full OS access / specific engine build / install my own agents' means IaaS — SQL Server on a VM.

AZ-900 Question 4 of 7

Ranking the SQL options from the most control (and most administration) to the most fully managed (and least administration), which order is correct?

Answer: A — SQL Server on a VM → Azure SQL Managed Instance → Azure SQL Database.

The SQL ladder runs from IaaS to PaaS: SQL Server on a VM gives the most control and the most admin work; Azure SQL Managed Instance sits in the middle, managed but instance-compatible; Azure SQL Database is the most fully managed with the least administration. So most-control-to-most-managed is VM → Managed Instance → SQL Database. Why not the others: the second option reverses the direction, and the third scrambles the middle. The fourth starts with Cosmos DB, which is NoSQL and not part of the SQL ladder at all. Pro tip: picture the diagram's ladder — control and admin increase as you step down toward the VM, management increases as you step up toward SQL Database.

AZ-900 Question 5 of 7

An app must serve reads and writes with single-digit-millisecond latency, store JSON documents (a non-relational, multi-model shape), and turn on distribution to new regions with a switch rather than a rebuild. Which fully managed Azure service is designed for this?

Answer: A — Azure Cosmos DB.

Azure Cosmos DB is Microsoft's globally distributed, multi-model, managed NoSQL database. It is built for low, predictable latency at scale and offers turnkey global distribution — you add regions with a setting, not a re-architecture — while storing documents and other non-relational shapes. That is exactly this profile. Why not the others: Azure SQL Database and Azure Database for MySQL are relational engines, not multi-model NoSQL, and do not offer Cosmos DB's turnkey global distribution. Blob Storage holds unstructured objects like files and images, not a queryable operational database. Pro tip: 'NoSQL + multi-model + single-digit-ms latency + turnkey global distribution' is the Cosmos DB fingerprint.

AZ-900 Question 6 of 7

A team already runs a production application on PostgreSQL and wants to move to Azure without rewriting the app to a different database engine — but they no longer want to patch or back up the server themselves. Which service fits best?

Answer: A — Azure Database for PostgreSQL.

Azure Database for PostgreSQL is a managed PaaS version of the open-source PostgreSQL engine, so the existing app keeps talking PostgreSQL while Microsoft takes over patching, backups, and availability — no engine rewrite required. (Azure Database for MySQL is the equivalent for MySQL apps.) Why not the others: Azure SQL Database is the SQL Server engine, so moving to it would mean changing engines. Cosmos DB is NoSQL, a bigger change still. SQL Server on a VM keeps the admin burden the team wants to shed and is the wrong engine anyway. Pro tip: 'keep my open-source engine (MySQL or PostgreSQL) but let Microsoft manage it' means Azure Database for MySQL / PostgreSQL.

AZ-900 Question 7 of 7

In the AZ-900, what is the main benefit of choosing a managed (PaaS) database over installing and running a database engine yourself on a virtual machine?

Answer: A — Microsoft handles operational tasks such as OS patching, backups, and high availability, so the team spends less time on server administration.

The defining benefit of a managed PaaS database is reduced operational overhead: Microsoft runs the underlying OS, applies patches, takes backups, and provides built-in high availability, freeing the team from routine server administration. Why not the others: cost depends on the workload — managed is not automatically cheapest, and the exam avoids absolute 'always' claims. You still design your schema and write your own queries; PaaS manages the platform, not your data model. And giving up host-level access is the trade-off of PaaS, not a benefit — installing host software is an IaaS (VM) capability. Pro tip: the PaaS database value proposition is 'less admin, not less design' — Microsoft runs the plumbing, you still own the data.

That is exactly how every question in the course works — answer, explanation, why-not. The real set continues in the practice player: 10 free questions, no sign-up.

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Frequently asked questions

What is the difference between Azure SQL Database and SQL Server on a VM?

Azure SQL Database is a fully managed PaaS service — Microsoft runs the operating system, patching, backups, and high availability, and you only work with the database. SQL Server on an Azure virtual machine is IaaS: you get full control of the OS and the exact SQL Server build, but you are responsible for patching, backups, and availability yourself. In short: SQL Database trades control for the least administration; SQL Server on a VM trades administration for the most control. Azure SQL Managed Instance sits between them — managed, but with near-full SQL Server compatibility.

When should I choose Azure Cosmos DB?

Choose Azure Cosmos DB when you need a non-relational (NoSQL) database with low, predictable latency and easy global reach. It is multi-model, offers turnkey global distribution — you add regions with a setting — and targets single-digit-millisecond response times at scale. If your data is relational (tables and joins), an Azure SQL option or a managed MySQL/PostgreSQL service is usually the better fit.

Are these real exam questions?

No. They are our own questions, written in the style and difficulty of the AZ-900 — never copied from any question bank or the real exam. Reproducing live exam items violates Microsoft's certification agreement and can cost a candidate their certification, and a crammed answer teaches you nothing about the one you have not seen.

Updated for AZ-900 (July 2026). The sample questions above are our own work in the style of the exam — not real exam items. The exam itself is set and marked by the certification body.