AZ-305 Design data storage solutions Practice Question
A company stores terabytes of archival data that must be retained for 10 years per regulatory requirements. The data is accessed infrequently (once or twice per year) and retrieval latency of up to 5 hours is acceptable. The company wants the lowest storage cost. They also need to ensure data is encrypted at rest and immutability to prevent deletion or modification during the retention period. Which Azure storage solution should they choose?
⚠ Common exam trap
It's easy for candidates to confuse legal hold (which is indefinite and does not prevent modification) with time-based retention immutability policy, or they incorrectly choose a higher-cost tier like Hot or Cool thinking lifecycle management will reduce costs, ignoring that the Archive tier itself is the cheapest and directly meets the latency 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
✓
Azure Blob Storage with Archive tier and immutability policy (time-based retention)
Azure Blob Storage's Archive tier offers the lowest storage cost for infrequently accessed data, and the immutability policy with time-based retention provides WORM (Write Once, Read Many) compliance to prevent deletion or modification for the required 10-year period. The 5-hour retrieval latency is acceptable for archival data accessed once or twice per year, and encryption at rest is automatically enabled for all Azure Blob Storage tiers.
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 Blob Storage with Hot tier and lifecycle management to Archive tier with WORM policy
Why it's wrong here
Although a lifecycle rule can eventually move blobs to Archive, this design is more expensive because blobs are initially stored in Hot tier, which bills at the highest per-GB storage price. Hot tier also incurs higher write and read operation costs before the transition, and lifecycle transitions may be delayed by minimum age conditions, leaving data in Hot longer. A WORM policy, implemented as a time-based retention immutability policy, is a compliance control and can be applied directly to Archive-tier blobs, so staging in Hot is neither cost-effective nor technically necessary.
- ✗
Azure Blob Storage with Cool tier and lifecycle management to Archive tier with legal hold
Why it's wrong here
Using Cool tier as an intermediate destination before lifecycle to Archive incurs unnecessary charges, because Archive tier is cheaper than Cool tier for every byte stored. A legal hold is an indefinite, manually managed immutability setting; it has no retention period or expiration and must be explicitly cleared, so it cannot implement a automated '10 years then release' compliance requirement. Lifecycle management changes access tiers but cannot apply or manage legal holds, and legal hold does not provide the scheduled, time-based immutability needed here.
- ✓
Azure Blob Storage with Archive tier and immutability policy (time-based retention)
Why this is correct
This design places blobs directly in Archive tier, which offers the lowest storage cost of any Blob Storage tier and is specifically designed for long-lived, rarely accessed data. A time-based retention immutability policy on the container can be locked, making it WORM-compliant and preventing blobs from being deleted or overwritten for the configured 10-year period. Because the retention period is enforced automatically and expires on schedule, and because no earlier tier is used, there are no unnecessary transition costs or manual steps.
- ✗
Azure Files with premium tier and soft delete
Why it's wrong here
Azure Files is a managed file share service built for SMB/NFS workloads requiring persistent, low-latency file access, and its premium tier uses SSDs at prices far higher than any archival storage option. It has no archive tier, so it cannot satisfy the 'lowest storage cost' requirement for terabytes of archival data. Soft delete in Azure Files only guards against accidental deletion by retaining a deleted share for a configurable period; it does not prevent authorized users from modifying or overwriting files, so it fails to provide the immutable WORM guarantee the retention policy demands.
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 |
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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.