This DP-900 practice question tests your understanding of describe core data concepts. 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.
You need to store semi-structured JSON documents from a web application in Azure. The data will be accessed by a key/value lookup. Which Azure data store should you use?
Azure Blob Storage
Why wrong: Designed for unstructured data like images and videos, not for querying JSON.
Azure Table Storage
Why wrong: Key-value store but limited querying of JSON content compared to Cosmos DB.
Azure Cosmos DB
NoSQL database that natively supports JSON documents and key-value lookups.
Azure SQL Database
Why wrong: Relational database, not ideal for semi-structured JSON key/value access.
Answer choices
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 choice because it natively supports semi-structured JSON documents and provides key/value lookup via its partition key mechanism. It offers single-digit millisecond latency for point reads, making it ideal for web application data that needs fast, scalable access by a unique key.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Azure Blob Storage
Why it's wrong here
Designed for unstructured data like images and videos, not for querying JSON.
Azure Table Storage
Why it's wrong here
Key-value store but limited querying of JSON content compared to Cosmos DB.
Azure Cosmos DB
Why this is correct
NoSQL database that natively supports JSON documents and key-value lookups.
Related concept
Read the scenario before looking for a memorised answer.
Azure SQL Database
Why it's wrong here
Relational database, not ideal for semi-structured JSON key/value access.
Common exam traps
The trap here is that candidates often confuse Azure Table Storage's key/value capabilities with JSON document support, but Table Storage stores flat entities, not nested JSON, and lacks native indexing for document fields.
Detailed technical explanation
Under the hood, Azure Cosmos DB uses a hash-based partition key to distribute data across physical partitions, enabling O(1) point reads when the partition key and item ID are provided. The JSON documents are stored as items in a container, and the API (e.g., SQL API) allows direct retrieval via `SELECT * FROM c WHERE c.id = 'value'` with the partition key. In a real-world scenario, a web app storing user profiles as JSON can achieve sub-10ms reads by using the user ID as the partition key, whereas Blob Storage would require downloading the entire blob and parsing it client-side.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
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FAQ
Describe core data concepts — This question tests Describe core data concepts — Read the scenario before looking for a memorised answer..
The correct answer is: Azure Cosmos DB — Azure Cosmos DB is the correct choice because it natively supports semi-structured JSON documents and provides key/value lookup via its partition key mechanism. It offers single-digit millisecond latency for point reads, making it ideal for web application data that needs fast, scalable access by a unique key.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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