- A
Azure Time Series Insights (TSI)
Azure TSI is purpose-built for time-series data, supports high ingestion, low-latency warm queries, automatic cold tiering, and built-in time-series analytics.
- B
Azure Cosmos DB with analytical store
Why wrong: Azure Cosmos DB is a general-purpose NoSQL database that can handle time-series but is less optimized for high-ingestion rates and low-latency time-series queries, and may have higher cost.
- C
Azure Event Hubs with Azure Data Lake Storage
Why wrong: Event Hubs is a data ingestion service, not a queryable storage service. Data Lake Storage provides cost-effective storage but does not offer low-latency warm queries or built-in time-series analytics.
- D
Azure SQL Database with elastic query
Why wrong: Azure SQL Database is a relational database and is not designed for high-ingestion time-series data or automatic cold tiering of historical data.
Quick Answer
The answer is Azure Time Series Insights (TSI). This service is purpose-built for high-throughput IoT time-series analytics, ingesting millions of events per second while delivering sub-100 ms query latency on warm data less than 30 days old. TSI automatically moves cold data to a cost-optimized warm/cold store and includes built-in analytics and visualization, directly matching the requirement for both real-time and occasional historical queries. On the AZ-305 exam, this scenario tests your ability to differentiate between purpose-built time-series services and general-purpose analytics like Azure Data Explorer or Cosmos DB. A common trap is choosing Azure Stream Analytics for the ingestion speed, but Stream Analytics lacks the automated cold tier and built-in time-series visualization that TSI provides. Remember the memory tip: “TSI is the time-series specialist—warm for speed, cold for cost.”
AZ-305 Design data storage solutions Practice Question
This AZ-305 practice question tests your understanding of design data storage solutions. 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 runs a high-throughput time-series workload that stores sensor data from IoT devices. Data is ingested at a rate of millions of events per second. The application requires low-latency queries (under 100 ms) on recent data (less than 30 days old) and the ability to run occasional analytical queries on historical data older than 30 days. The solution must automatically move cold data to a cost-optimized tier and provide built-in analytics. Which Azure service should they use?
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
Azure Time Series Insights (TSI)
Azure Time Series Insights (TSI) is purpose-built for high-throughput IoT time-series data, supporting millions of events per second with sub-100 ms query latency on warm data (less than 30 days old). It automatically moves cold data to a cost-optimized warm/cold store and provides built-in analytics and visualization for time-series patterns, making it the ideal choice for this scenario.
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 Time Series Insights (TSI)
Why this is correct
Azure TSI is purpose-built for time-series data, supports high ingestion, low-latency warm queries, automatic cold tiering, and built-in time-series analytics.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Azure Cosmos DB with analytical store
Why it's wrong here
Azure Cosmos DB is a general-purpose NoSQL database that can handle time-series but is less optimized for high-ingestion rates and low-latency time-series queries, and may have higher cost.
- ✗
Azure Event Hubs with Azure Data Lake Storage
Why it's wrong here
Event Hubs is a data ingestion service, not a queryable storage service. Data Lake Storage provides cost-effective storage but does not offer low-latency warm queries or built-in time-series analytics.
- ✗
Azure SQL Database with elastic query
Why it's wrong here
Azure SQL Database is a relational database and is not designed for high-ingestion time-series data or automatic cold tiering of historical data.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose Azure Cosmos DB or Event Hubs because they are familiar with high-throughput ingestion, but they overlook the specific requirement for built-in time-series analytics and automatic cold data tiering, which TSI uniquely provides out of the box.
Detailed technical explanation
How to think about this question
Azure Time Series Insights uses a columnar storage format optimized for time-series data, enabling efficient compression and fast range scans on timestamped data. Its warm store retains data in memory for sub-100 ms queries, while the cold store uses Azure Blob Storage for cost-effective long-term retention, with automatic tiering based on configurable retention policies. In a real-world scenario, a manufacturing plant ingesting sensor data from thousands of devices can query recent temperature trends instantly and run historical anomaly detection on cold data without manual data movement.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Design data storage solutions — study guide chapter
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Design data storage solutions practice questions
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FAQ
Questions learners often ask
What does this AZ-305 question test?
Design data storage solutions — This question tests Design data storage solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Azure Time Series Insights (TSI) — Azure Time Series Insights (TSI) is purpose-built for high-throughput IoT time-series data, supporting millions of events per second with sub-100 ms query latency on warm data (less than 30 days old). It automatically moves cold data to a cost-optimized warm/cold store and provides built-in analytics and visualization for time-series patterns, making it the ideal choice for this scenario.
What should I do if I get this AZ-305 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.
About these practice questions
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Last reviewed: Jun 11, 2026
This AZ-305 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 AZ-305 exam.
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