AZ-305 Design data storage solutions Practice Question
This AZ-305 practice question tests your understanding of design data storage solutions. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A financial services company needs to store transaction logs for regulatory compliance. The logs must be stored in a cost-effective manner, and they must be immutable to prevent tampering. The logs are accessed infrequently but must be retained for 7 years. Which Azure storage solution should you recommend?
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 immutable storage policy and cool access tier
Azure Blob Storage with an immutable storage policy (WORM) ensures that transaction logs cannot be modified or deleted during the retention period, meeting compliance requirements. The cool access tier is cost-effective for infrequently accessed data, and the 7-year retention aligns with the policy's time-based retention. This combination provides both immutability and low-cost storage for long-term archival.
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.
✗
Azure Cosmos DB with time-to-live (TTL)
Why it's wrong here
Cosmos DB is a database, not designed for log storage.
✓
Azure Blob Storage with immutable storage policy and cool access tier
Read the scenario before looking for a memorised answer.
✗
Azure SQL Database with long-term retention backup
Why it's wrong here
Not cost-effective for large-scale log storage.
✗
Azure Files with share snapshots
Why it's wrong here
Share snapshots provide point-in-time recovery but not immutability.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse Azure SQL Database long-term retention (which is for backup recovery, not immutable storage) with true immutability, or assume that any snapshot or TTL mechanism can satisfy regulatory immutability requirements when they actually allow deletion or modification.
Detailed technical explanation
How to think about this question
Immutable storage in Azure Blob uses a WORM (Write Once, Read Many) policy enforced at the container level, leveraging time-based retention locks that prevent any deletion or modification until the retention period expires. The cool access tier has lower storage costs but higher access costs, making it ideal for logs accessed only a few times per year. Under the hood, the immutable policy is enforced by the Azure Storage resource provider, which rejects any PUT or DELETE operations that would violate the retention lock, even for privileged accounts.
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: Azure Blob Storage with immutable storage policy and cool access tier — Azure Blob Storage with an immutable storage policy (WORM) ensures that transaction logs cannot be modified or deleted during the retention period, meeting compliance requirements. The cool access tier is cost-effective for infrequently accessed data, and the 7-year retention aligns with the policy's time-based retention. This combination provides both immutability and low-cost storage for long-term archival.
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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