DP-900 Describe core data concepts Practice Question
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.
A company wants to store JSON documents from IoT devices with low latency and high availability. Which Azure data store should they use?
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 is a fully managed NoSQL database designed for low-latency, high-availability workloads, with native support for JSON documents. It offers single-digit millisecond read/write latencies at the 99th percentile, global distribution with multi-region writes, and multiple consistency models, making it ideal for IoT scenarios that require fast, always-on access to semi-structured data.
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 Blob Storage
Why it's wrong here
Azure Blob Storage is for unstructured data like files, not optimized for querying JSON documents.
✓
Azure Cosmos DB
Why this is correct
Azure Cosmos DB is a globally distributed NoSQL database that natively supports JSON documents.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Table Storage
Why it's wrong here
Azure Table Storage is a key-value store, not designed for JSON documents.
✗
Azure SQL Database
Why it's wrong here
Azure SQL Database supports JSON but is not the best for IoT scenarios needing low latency and high throughput.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Azure Blob Storage's ability to store JSON files with the need for a database that can natively query and index JSON documents, leading them to choose Blob Storage for its low cost rather than Cosmos DB for its low-latency querying capabilities.
Trap categories for this question
Scenario analysis trap
Azure SQL Database supports JSON but is not the best for IoT scenarios needing low latency and high throughput.
Detailed technical explanation
How to think about this question
Under the hood, Cosmos DB uses a write-optimized, log-structured index (LSM-tree) and a multi-master replication protocol to achieve its low-latency guarantees. Its resource governance model uses Request Units (RUs) to provision throughput, allowing predictable performance even under spiky IoT workloads. A real-world scenario is a fleet of temperature sensors sending JSON payloads every second; Cosmos DB can ingest millions of writes per second with automatic indexing of each JSON property, enabling real-time dashboards without schema management.
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 DP-900 question in full detail.
Describe core data concepts — This question tests Describe core data concepts — 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 choice because it is a fully managed NoSQL database designed for low-latency, high-availability workloads, with native support for JSON documents. It offers single-digit millisecond read/write latencies at the 99th percentile, global distribution with multi-region writes, and multiple consistency models, making it ideal for IoT scenarios that require fast, always-on access to semi-structured data.
What should I do if I get this DP-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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