Describe considerations for working with non-relational data on Azure →mediumMultiple ChoiceObjective-mapped
DP-900 Practice Question: Describe considerations for working with non-relational data on Azure
A company stores historical sensor data in Azure Blob Storage. The data is accessed only a few times per year for compliance audits, but when requested, it must be available for reading within 15 minutes. The company wants to minimize storage costs. Which blob access tier should they use?
⚠ Common exam trap
Candidates often choose Archive for its lowest storage cost without considering the mandatory rehydration delay, which can take up to 15 hours and violates the 15-minute availability requirement.
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
✓
Cool
The Cool tier is the optimal choice because it balances low storage cost with the ability to retrieve data within minutes, meeting the 15-minute availability requirement. Archive would incur a retrieval delay of up to 15 hours, which violates the compliance audit SLA. Hot and Premium tiers are more expensive and unnecessary for data accessed only a few times per year.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Hot
Why it's wrong here
The Hot tier is optimized for frequent read and write operations, so it has the highest storage cost among the online tiers. Since the sensor data is accessed only a few times per year, you would be paying a premium to keep every object on always-ready, high-throughput storage, and even though access charges are lower, total cost of ownership would still be excessive. This overprovisioning makes Hot a poor financial choice even though it could technically retrieve data quickly.
When this WOULD be correct
If the data were accessed frequently (e.g., multiple times per day or week) and required low latency, Hot would be the correct tier to minimize access costs and ensure fast retrieval.
- ✓
Cool
Why this is correct
The Cool access tier is correct because it is designed for data that is infrequently accessed and retained for at least 30 days, such as historical sensor readings. It has significantly lower storage cost than Hot, and while reads cost more per transaction, the data remains immediately readable or can be retrieved in minutes without the long rehydration wait of Archive. This satisfies the 15-minute availability requirement at a lower cost.
- ✗
Archive
Why it's wrong here
Archive has the lowest storage cost because objects are stored in an offline state and must be rehydrated before they can be read. Rehydration typically takes several hours—and can take up to 15 hours in the worst case—which far exceeds the stated 15-minute availability requirement. Even with high-priority rehydration, it may not reliably meet that SLA, so Archive is disqualified despite its cost advantage.
When this WOULD be correct
If the data is rarely accessed and can tolerate a retrieval time of up to 15 hours (e.g., for long-term backup or archival compliance with no time-sensitive retrieval), Archive tier would minimize storage costs.
- ✗
Premium
Why it's wrong here
Premium, typically backed by high-performance SSD storage, is designed for workloads requiring consistently low latency and high transaction rates, not for rarely accessed historical data. Its per-GB storage cost is substantially higher than the standard tiers, and it does not offer a cost advantage for data that will be read only a few times per year. This makes Premium an unnecessarily expensive option that provides no business benefit for slow archival telemetry.
When this WOULD be correct
When the question specifies that data requires sub-millisecond latency for frequent reads (e.g., real-time analytics) and cost is not the primary concern, Premium would be correct.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The DP-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓CoolCorrect answer▾
Why this is correct
The Cool access tier is correct because it is designed for data that is infrequently accessed and retained for at least 30 days, such as historical sensor readings. It has significantly lower storage cost than Hot, and while reads cost more per transaction, the data remains immediately readable or can be retrieved in minutes without the long rehydration wait of Archive. This satisfies the 15-minute availability requirement at a lower cost.
✗HotWrong answer — click to see why▾
Why this is wrong here
The Hot tier is designed for frequently accessed data and has higher storage costs than Cool. Since the data is accessed only a few times per year, using Hot would unnecessarily increase costs.
★ When this WOULD be the correct answer
If the data were accessed frequently (e.g., multiple times per day or week) and required low latency, Hot would be the correct tier to minimize access costs and ensure fast retrieval.
Why candidates choose this
Candidates may assume that 'Hot' is always the best for availability, overlooking that the question prioritizes cost minimization over access speed, and that the 15-minute retrieval requirement is still met by Cool.
✗ArchiveWrong answer — click to see why▾
Why this is wrong here
Archive tier has a retrieval time of up to 15 hours, which exceeds the 15-minute availability requirement for compliance audits.
★ When this WOULD be the correct answer
If the data is rarely accessed and can tolerate a retrieval time of up to 15 hours (e.g., for long-term backup or archival compliance with no time-sensitive retrieval), Archive tier would minimize storage costs.
Why candidates choose this
Candidates may assume 'historical' and 'few times per year' automatically mean Archive, overlooking the specific 15-minute retrieval requirement.
✗PremiumWrong answer — click to see why▾
Why this is wrong here
Premium tier is designed for low-latency, high-performance scenarios (e.g., interactive apps) and is the most expensive, contradicting the goal of minimizing storage costs for infrequently accessed data.
★ When this WOULD be the correct answer
When the question specifies that data requires sub-millisecond latency for frequent reads (e.g., real-time analytics) and cost is not the primary concern, Premium would be correct.
Why candidates choose this
Candidates may mistakenly think 'Premium' implies better overall value or faster retrieval for any scenario, overlooking its high cost and that it's meant for high-performance workloads.
Analysis generated from the official DP-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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 |
Go deeper
Related to this question
Learn chapter
Data Roles and Core Concepts
Key term
Blob storage
Blob storage is a cloud service for storing large amounts of unstructured data, such as text or binary data, like documents, images, and videos.
Key term
Data
Data is raw, unprocessed information, like numbers, words, or measurements, that can be stored, processed, and analyzed by computers.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DP-900 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-900 exam.