Azure Cosmos DB for Apache Cassandra is the correct choice because it delivers NoSQL wide-column database storage with native compatibility for Apache Cassandra, allowing you to use the Cassandra Query Language (CQL) and existing Cassandra drivers without any code changes. This service combines Cassandra’s familiar wide-column model with Cosmos DB’s globally distributed, SLA-backed performance, making it the only Azure offering that directly supports Cassandra workloads. On the AZ-900 exam, this question tests your understanding of Azure’s database portfolio, specifically how Cosmos DB adapts to different NoSQL models; a common trap is confusing it with Azure Table Storage or a standard Cosmos DB SQL API, which lack Cassandra wire-protocol compatibility. Remember the memory tip: “Cassandra on Cosmos” — if the question mentions wide-column and Cassandra compatibility, the answer is always Azure Cosmos DB for Apache Cassandra.
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 service provides NoSQL wide-column database storage compatible with Apache Cassandra?
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 for Apache Cassandra
Azure Cosmos DB for Apache Cassandra is the correct choice because it provides a NoSQL wide-column database storage that is fully compatible with the Apache Cassandra Query Language (CQL) and wire protocol. This allows you to run existing Cassandra workloads and tools (like cqlsh and Cassandra drivers) directly on Azure without any code changes, while benefiting from Cosmos DB's global distribution and SLA-backed performance.
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 Table Storage
Why it's wrong here
Table Storage is Azure's basic NoSQL key-value store, not Cassandra-compatible.
✓
Azure Cosmos DB for Apache Cassandra
Why this is correct
Cosmos DB for Cassandra provides wide-column NoSQL storage with Cassandra wire protocol and CQL compatibility.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Cache for Redis
Why it's wrong here
Redis Cache is an in-memory key-value store, not a wide-column Cassandra-compatible database.
✗
Azure SQL Database Hyperscale
Why it's wrong here
SQL Hyperscale is a high-scale relational database, not a NoSQL Cassandra-compatible solution.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse Azure Table Storage (a key-value store) with a wide-column database, or assume that any NoSQL service (like Redis) can substitute for Cassandra's specific data model and protocol compatibility.
Detailed technical explanation
How to think about this question
Under the hood, Azure Cosmos DB for Apache Cassandra implements the Cassandra wire protocol (including native transport protocol v4 and CQL) on top of Cosmos DB's globally distributed, multi-model architecture. This means you get Cassandra's familiar data model (partition keys, clustering columns, and tunable consistency) combined with Cosmos DB's turnkey global distribution, automatic indexing, and 99.999% availability SLAs. A real-world scenario is migrating an on-premises Cassandra cluster to Azure without rewriting application code, while gaining the ability to elastically scale throughput and storage across multiple regions.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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 for Apache Cassandra — Azure Cosmos DB for Apache Cassandra is the correct choice because it provides a NoSQL wide-column database storage that is fully compatible with the Apache Cassandra Query Language (CQL) and wire protocol. This allows you to run existing Cassandra workloads and tools (like cqlsh and Cassandra drivers) directly on Azure without any code changes, while benefiting from Cosmos DB's global distribution and SLA-backed performance.
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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