DP-203 Design and implement data storage Practice Question
This DP-203 practice question tests your understanding of design and implement data storage. 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 is designing a data lake solution on Azure Data Lake Storage Gen2. Data will be ingested from IoT devices at high frequency (every 5 seconds). Each device sends a JSON payload of 2 KB. The data must be stored in a hierarchical namespace and partitioned by date and device ID to optimize query performance. Which partition strategy should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Organize folders as /YYYY/MM/DD/DeviceID/ in ADLS Gen2 and use file naming that includes timestamp.
Option B is correct because ADLS Gen2 with a hierarchical namespace allows folder-based partitioning by date and device ID (e.g., /YYYY/MM/DD/DeviceID/), which directly maps to the query optimization requirement. This structure enables efficient partition pruning for time-range and device-specific queries, and the high-frequency 2 KB JSON payloads are well-suited for append-friendly file naming with timestamps.
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.
✗
Use Azure SQL Database with clustered columnstore index on date and device ID.
Why it's wrong here
Azure SQL Database is a relational store, not a data lake, and cannot handle high-frequency ingest efficiently.
✓
Organize folders as /YYYY/MM/DD/DeviceID/ in ADLS Gen2 and use file naming that includes timestamp.
Why this is correct
This folder structure enables efficient partition pruning based on date and device ID.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use Azure Table Storage with PartitionKey set to date and RowKey set to device ID.
Why it's wrong here
Azure Table Storage does not support hierarchical namespace and is not a data lake solution.
✗
Use Azure Cosmos DB with partition key on (date, device ID) and TTL for data retention.
Why it's wrong here
Cosmos DB is not a hierarchical namespace data lake; it's a NoSQL database.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse storage services (ADLS Gen2) with database or NoSQL solutions (SQL Database, Table Storage, Cosmos DB), failing to recognize that the question explicitly requires a data lake with a hierarchical namespace, which only ADLS Gen2 provides.
Detailed technical explanation
How to think about this question
ADLS Gen2 hierarchical namespace enables true directory-level ACLs and atomic rename/delete operations, which are critical for managing high-frequency IoT data. Partitioning by date first (e.g., /YYYY/MM/DD/) ensures that time-range queries scan only relevant folders, while sub-partitioning by DeviceID allows parallel reads across devices. File naming with timestamps (e.g., device_20250320T120000.json) avoids file collisions and supports idempotent writes in append-heavy ingestion pipelines.
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-203 question in full detail.
Design and implement data storage — This question tests Design and implement data storage — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Organize folders as /YYYY/MM/DD/DeviceID/ in ADLS Gen2 and use file naming that includes timestamp. — Option B is correct because ADLS Gen2 with a hierarchical namespace allows folder-based partitioning by date and device ID (e.g., /YYYY/MM/DD/DeviceID/), which directly maps to the query optimization requirement. This structure enables efficient partition pruning for time-range and device-specific queries, and the high-frequency 2 KB JSON payloads are well-suited for append-friendly file naming with timestamps.
What should I do if I get this DP-203 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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