DP-203 Design and implement data storage Practice Question
You are designing a data storage solution for a retail company. The data includes transactional data that requires low-latency queries (under 10 milliseconds) and large historical data for analytics. The solution must minimize storage costs. Which approach should you recommend?
⚠ Common exam trap
A common mix-up: candidates assume a single service like Azure SQL Database or Data Lake Storage can handle both transactional and analytical workloads efficiently, overlooking the cost and performance trade-offs that make a hybrid approach optimal.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Azure Cosmos DB for transactional data and Azure Blob Storage for historical data
Azure Cosmos DB provides single-digit millisecond latency for transactional workloads, meeting the under-10ms requirement, while Azure Blob Storage offers low-cost storage for large historical data. This combination minimizes storage costs by using the most cost-effective service for each workload type.
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 Data Lake Storage Gen2 for both transactional and historical data
Why it's wrong here
Data Lake Storage is optimized for analytics, not low-latency transactions.
- ✗
Use Azure Cache for Redis for transactional data and Azure SQL Database for historical data
Why it's wrong here
Redis is a cache, not a durable data store; it cannot replace a transactional database.
- ✓
Use Azure Cosmos DB for transactional data and Azure Blob Storage for historical data
Why this is correct
Cosmos DB offers low-latency reads/writes, and Blob Storage is cheap for bulk historical data.
- ✗
Use Azure SQL Database with Hyperscale tier for both transactional and historical data
Why it's wrong here
Hyperscale is for large databases but not guaranteed sub-10ms latency for transactions.
Quick reference
Azure Blob Storage Tier Comparison
| Tier | Storage Cost | Retrieval Cost | Latency | Use Case |
|---|---|---|---|---|
| Hot | Highest | Lowest | Immediate | Active data, frequent reads |
| Cool | Lower | Higher | Immediate | Data accessed < once / month |
| Cold | Lower still | Higher | Immediate | Data accessed < once / quarter |
| Archive | Lowest | Highest + rehydration delay | Hours | Long-term compliance retention |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DP-203 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DP-203 exam.