AZ-305 Design data storage solutions Practice Question
You are designing a solution to store large binary files (videos) that are accessed infrequently but must be retained for 7 years for compliance. The solution must minimize storage costs while allowing retrieval within 24 hours. Which Azure storage tier should you use?
⚠ Common exam trap
It's easy for candidates to choose Cool tier because they see 'infrequent access' and '24-hour retrieval' and mistakenly think Archive's retrieval time is too slow, but the question explicitly allows up to 24 hours, making Archive the correct cost-optimized choice.
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
✓
Archive tier
The Archive tier is the correct choice because it is the lowest-cost storage tier for infrequently accessed data that must be retained for long periods (7 years). It allows retrieval within 24 hours via standard rehydration, meeting the compliance requirement while minimizing storage costs. The other tiers (Premium, Hot, Cool) are more expensive and designed for higher-frequency access, making them unsuitable for this cost-optimization scenario.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Premium tier
Why it's wrong here
Azure Premium Blob Storage is optimized for low-latency, high-throughput workloads using SSDs, not for data that is simply stored for long periods. Its per-gigabyte price is roughly the highest among blob tiers, and it charges for operations regardless of access rarity, making it financially impractical for archival of large binaries. The tier also uses fixed-size charge units that can inflate costs when storing many small objects, which is the opposite of an archive use case.
- ✗
Cool tier
Why it's wrong here
Cool storage is intended for data that is accessed a few times per quarter, with a 30-day minimum retention period and per-gigabyte retrieval costs that are lower than Hot but still nontrivial. Its monthly storage rate is more expensive than Archive, and because the data is only occasionally needed, the combination of moderate storage cost plus access fees quickly exceeds Archive's total cost. Additionally, Cool does not offer the same low per-terabyte cost that Archive guarantees for multi-year retention.
- ✗
Hot tier
Why it's wrong here
The Hot tier assumes frequent reads and writes, with no minimum storage duration but the highest monthly per-gigabyte price of the online tiers. For large binary files that will remain untouched for months or years, leaving them in Hot means paying a premium for access speed that is never used. Over a long retention period, the cumulative storage charges dwarf any potential savings from avoiding rehydration delays.
- ✓
Archive tier
Why this is correct
The Archive tier has the lowest per-gigabyte storage cost in Azure Blob Storage, making it the designated choice for long-term retention where data is rarely accessed. It requires rehydration to a Hot or Cool tier before reading, with a retrieval latency of up to 15 hours (typically a few hours), which is acceptable for archival scenarios. A 180-day minimum storage period and higher per-GB retrieval fees are the trade-offs, but for large binaries stored for years, the storage cost savings dominate.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.