The answer is to use Azure Blob Storage with lifecycle management, transitioning data from Hot to Cool to Archive tiers based on age. This strategy minimizes costs for IoT telemetry because the Hot tier supports low-latency interactive queries during the first 90 days, while the Cool tier reduces storage expenses for infrequent access, and the Archive tier provides the lowest cost for the remaining three years of mandatory retention. On the AZ-305 exam, this scenario tests your understanding of Azure Blob Storage lifecycle management for IoT telemetry cost optimization, often appearing as a design question where the trap is selecting a single tier like Cool-only, which fails to balance query performance with long-term savings. Remember the mnemonic “HCA” for Hot, Cool, Archive—matching the data’s lifespan: 90 days hot, then cool down, then archive away.
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.
Your company is designing a data lake solution for IoT telemetry data. The data is ingested continuously and must be stored cost-effectively while allowing occasional interactive queries. The data has a lifespan of 90 days for hot access and 3 years for archived access. Which Azure storage tiering strategy minimizes costs?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Azure Blob Storage with lifecycle management: Hot for 90 days, then Cool, then Archive after 3 years
Option B is correct because Azure Blob Storage lifecycle management can automatically transition data from Hot to Cool to Archive tiers based on age, minimizing costs for IoT telemetry that needs 90 days of hot access and 3 years of archival. The Hot tier provides low-latency access for interactive queries, Cool offers lower storage cost for infrequent access, and Archive provides the lowest cost for long-term retention. This tiering strategy aligns with the data's lifespan and access patterns, reducing overall storage expenses compared to keeping all data in a single tier.
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 Blob Storage with only Hot tier for 90 days, then delete
Why it's wrong here
Deleting after 90 days does not meet the 3-year archive requirement.
✓
Use Azure Blob Storage with lifecycle management: Hot for 90 days, then Cool, then Archive after 3 years
Why this is correct
Lifecycle management optimizes cost by moving data through tiers.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use Azure Blob Storage with Cool tier for all data
Why it's wrong here
Cool tier is not optimal for frequently accessed hot data.
✗
Use Azure Files with lifecycle management to Archive after 90 days
Why it's wrong here
Azure Files is not a data lake solution and has limited archive tier.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may assume Cool tier is sufficient for all data to save costs, but they overlook the need for hot access during the first 90 days and the even lower Archive tier for long-term retention, leading to higher overall costs.
Detailed technical explanation
How to think about this question
Azure Blob Storage lifecycle management uses rules based on the 'Last Modified' or 'Creation Time' blob property to trigger tier transitions, with a minimum of 30 days in Hot before moving to Cool and 30 days in Cool before moving to Archive. The Archive tier has a 30-day minimum storage charge and requires rehydration (which can take up to 15 hours) before data can be read, so it is ideal for data that is rarely accessed. In a real-world IoT scenario, telemetry data often becomes less valuable over time, making this automated tiering a cost-effective solution that balances access latency with storage cost.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-305 question in full detail.
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: Use Azure Blob Storage with lifecycle management: Hot for 90 days, then Cool, then Archive after 3 years — Option B is correct because Azure Blob Storage lifecycle management can automatically transition data from Hot to Cool to Archive tiers based on age, minimizing costs for IoT telemetry that needs 90 days of hot access and 3 years of archival. The Hot tier provides low-latency access for interactive queries, Cool offers lower storage cost for infrequent access, and Archive provides the lowest cost for long-term retention. This tiering strategy aligns with the data's lifespan and access patterns, reducing overall storage expenses compared to keeping all data in a single tier.
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.
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Question Discussion
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