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DP-900 Practice Question: Describe considerations for working with non-relational data on Azure

A healthcare organization stores medical imaging files (DICOM) that are actively used by radiologists for the first 30 days. After 30 days, the files are accessed infrequently for up to 5 years. After 5 years, they must be retained for legal compliance but are accessed very rarely. The organization wants to minimize storage costs. Which strategy should they use to manage the data lifecycle in Azure Blob Storage?

⚠ Common exam trap

Test-takers frequently assume the Archive tier is always the cheapest option from day one, ignoring the high retrieval costs and latency for actively used data, or they overlook the need for a graduated tier strategy to match changing access patterns.

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

Store files in the Hot tier, move to Cool tier after 30 days, then to Archive tier after 5 years.

It aligns the data lifecycle with the access patterns: Hot tier for frequent initial access, Cool tier for infrequent access after 30 days, and Archive tier for long-term compliance after 5 years. Azure Blob Storage lifecycle management policies can automate these transitions, minimizing costs by using the most cost-effective tier for each phase.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Store all files in the Hot tier and use lifecycle management to move to the Archive tier after 5 years.

    Why it's wrong here

    Moving directly from Hot to Archive after 5 years is better than staying in Hot forever, but it misses the cost reduction available during the intermediate period. Between 30 days and 5 years, the files are still occasionally accessed for follow-up or comparisons, so keeping them in the Hot tier for the entire five years is wasteful; the Cool tier offers lower storage cost while still providing low-latency access. A lifecycle policy that moves to Cool after 30 days and then to Archive after 5 years minimizes cost at each stage.

    When this WOULD be correct

    If the question stated that files are accessed frequently for the first 30 days, then accessed very rarely after that, but with a compliance requirement to retain for 5 years without any intermediate access pattern, moving directly to Archive after 5 years would be appropriate.

  • Store files in the Hot tier, move to Cool tier after 30 days, then to Archive tier after 5 years.

    Why this is correct

    This lifecycle strategy aligns storage cost with data access patterns: the Hot tier supports frequent reads during the first 30 days when imaging files are actively used, the Cool tier lowers cost during the subsequent infrequent-access period, and the Archive tier provides the least expensive long-term retention after 5 years during which the data is rarely needed. Applying lifecycle management automates the transitions, avoiding both the high storage cost of keeping files in Hot for years and the retrieval latency of Archive for files that are still being accessed.

  • Store all files in the Archive tier from the beginning to minimize cost.

    Why it's wrong here

    Archiving files immediately minimizes storage cost, but it makes sense only for data that is truly immutable and never accessed; medical images in the first 30 days are frequently read by clinicians, and Archive access requires rehydrating the blob first, which can take up to 15 hours and incurs data retrieval charges. Therefore, the operational cost and latency far outweigh the storage savings during the active period, making this strategy unsuitable. It also violates the practical requirement that active medical images be available on demand.

    When this WOULD be correct

    A question where data is never accessed actively, only retained for long-term compliance with no immediate retrieval needs, e.g., 'A company must store financial audit logs for 7 years with zero access expected; which tier minimizes cost?'

  • Store all files in the Cool tier to balance cost and access.

    Why it's wrong here

    Using only the Cool tier is more expensive than it needs to be because after 5 years the files are almost never accessed, yet Cool's storage price remains significantly higher than Archive's. While Cool offers a balance of cost and low-latency access for moderately accessed data, it does not capture the savings of moving truly cold files to Archive. Over a long retention time typical for medical imaging, avoiding Archive means paying a premium for retrieval capabilities that are rarely used.

    When this WOULD be correct

    If the question stated that data is accessed infrequently from the start (e.g., monthly) and must be retained for 5 years with no need for immediate access, storing all files in the Cool tier would balance cost and access without requiring lifecycle management.

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.

Store files in the Hot tier, move to Cool tier after 30 days, then to Archive tier after 5 years.Correct answer

Why this is correct

This lifecycle strategy aligns storage cost with data access patterns: the Hot tier supports frequent reads during the first 30 days when imaging files are actively used, the Cool tier lowers cost during the subsequent infrequent-access period, and the Archive tier provides the least expensive long-term retention after 5 years during which the data is rarely needed. Applying lifecycle management automates the transitions, avoiding both the high storage cost of keeping files in Hot for years and the retrieval latency of Archive for files that are still being accessed.

Store all files in the Hot tier and use lifecycle management to move to the Archive tier after 5 years.Wrong answer — click to see why

Why this is wrong here

This option fails to move files to the Cool tier after 30 days, missing cost savings during the infrequent access period (30 days to 5 years). Keeping files in Hot tier for 5 years incurs higher storage costs than necessary.

★ When this WOULD be the correct answer

If the question stated that files are accessed frequently for the first 30 days, then accessed very rarely after that, but with a compliance requirement to retain for 5 years without any intermediate access pattern, moving directly to Archive after 5 years would be appropriate.

Why candidates choose this

Candidates may think that only the final archive step matters for cost savings, overlooking the cost benefit of moving to Cool tier during the infrequent access period.

Store all files in the Archive tier from the beginning to minimize cost.Wrong answer — click to see why

Why this is wrong here

Storing all files in the Archive tier from the beginning would make them unavailable for immediate access by radiologists during the first 30 days, as Archive tier requires rehydration (up to 15 hours) before reading.

★ When this WOULD be the correct answer

A question where data is never accessed actively, only retained for long-term compliance with no immediate retrieval needs, e.g., 'A company must store financial audit logs for 7 years with zero access expected; which tier minimizes cost?'

Why candidates choose this

Candidates see 'minimize cost' and assume Archive tier is always cheapest, overlooking that it cannot serve active access needs and incurs high retrieval costs if accessed frequently.

Store all files in the Cool tier to balance cost and access.Wrong answer — click to see why

Why this is wrong here

The Cool tier is not cost-optimal for data that is actively used for the first 30 days, and it does not provide the lowest cost for long-term retention after 5 years. The Hot tier is needed for active access, and the Archive tier is required for minimal cost after 5 years.

★ When this WOULD be the correct answer

If the question stated that data is accessed infrequently from the start (e.g., monthly) and must be retained for 5 years with no need for immediate access, storing all files in the Cool tier would balance cost and access without requiring lifecycle management.

Why candidates choose this

Candidates may think the Cool tier is a good middle ground that reduces cost compared to Hot while still allowing access, overlooking that the Hot tier is cheaper for the first 30 days of active use and the Archive tier is much cheaper for long-term retention.

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

TierStorage CostRetrieval CostLatencyUse Case
HotHighestLowestImmediateActive data, frequent reads
CoolLowerHigherImmediateData accessed < once / month
ColdLower stillHigherImmediateData accessed < once / quarter
ArchiveLowestHighest + rehydration delayHoursLong-term compliance retention

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Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

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