Azure Cosmos DB is the correct choice because it is the only Azure database service that supports both relational (SQL) and non-relational (NoSQL) data models with multi-master global distribution. This means Cosmos DB can handle document, key-value, graph, and column-family data while allowing writes to be accepted in any Azure region, automatically replicating changes across the globe with conflict resolution. On the Microsoft Azure Fundamentals AZ-900 exam, this question tests your understanding of Azure’s database portfolio and the unique value of Cosmos DB as a globally distributed, multi-model solution. A common trap is confusing Azure SQL Database, which is single-model and single-master, with Cosmos DB’s ability to span regions for both reads and writes. To remember, think of “Cosmos” as the universe of data models—SQL, NoSQL, and beyond—all connected across the globe with multi-master replication.
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.
Which Azure database service supports both relational (SQL) and non-relational (NoSQL) data models with multi-master global distribution?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Cosmos DB
Azure Cosmos DB is the correct answer because it is a globally distributed, multi-model database service that natively supports both SQL (relational) and NoSQL (non-relational) data models, including document, key-value, graph, and column-family. It offers multi-master replication, enabling writes to be accepted at any region with automatic conflict resolution, which is a unique capability not found in the other listed services.
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 SQL Database
Why it's wrong here
Azure SQL is a relational-only database without multi-model support or global multi-master writes.
✗
Azure Database for PostgreSQL Hyperscale
Why it's wrong here
PostgreSQL Hyperscale distributes Postgres workloads but is not a multi-model global database.
✓
Azure Cosmos DB
Why this is correct
Cosmos DB supports multiple data models (SQL, MongoDB, Cassandra, Graph, Table) with global multi-master distribution.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Synapse Analytics
Why it's wrong here
Synapse is for analytics/data warehousing, not a multi-model transactional database.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Azure SQL Database's elastic scale or Azure Synapse's distributed query capabilities with true multi-model and multi-master support, but only Cosmos DB provides native multi-master writes and support for both relational and non-relational data models.
Detailed technical explanation
How to think about this question
Cosmos DB achieves multi-master distribution through its multi-region writes capability, which uses a conflict resolution mechanism (e.g., last-writer-wins or custom conflict resolution policies) to handle concurrent writes across regions. It exposes multiple APIs (SQL, MongoDB, Cassandra, Gremlin, Table) that allow developers to use familiar query languages while benefiting from the underlying globally distributed, horizontally partitioned storage engine. In a real-world scenario, a global e-commerce platform can use Cosmos DB to serve low-latency reads and writes from any region, with automatic failover and no downtime during regional outages.
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 Cosmos DB — Azure Cosmos DB is the correct answer because it is a globally distributed, multi-model database service that natively supports both SQL (relational) and NoSQL (non-relational) data models, including document, key-value, graph, and column-family. It offers multi-master replication, enabling writes to be accepted at any region with automatic conflict resolution, which is a unique capability not found in the other listed services.
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.
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Question Discussion
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