AZ-305 Design data storage solutions Practice Question
A financial services company needs to store sensitive transaction records in Azure for 7 years to meet regulatory compliance. The data must be immutable and cannot be deleted or modified during the retention period. Which Azure storage feature should you enable?
⚠ Common exam trap
Many exam-takers confuse soft delete or versioning with immutability, not realizing that only immutable blob storage provides true WORM protection that prevents any modification or deletion during the retention period.
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
✓
Immutable blob with time-based retention policy
Immutable blob storage with a time-based retention policy enforces WORM (Write Once, Read Many) compliance, ensuring that data cannot be deleted or modified for a specified retention period. This meets the 7-year regulatory requirement for sensitive transaction records, as the policy locks the data at the blob level and prevents any overwrite or deletion, even by administrators with elevated permissions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Blob versioning with lifecycle management
Why it's wrong here
Blob versioning with lifecycle management does not enforce write-once-read-many (WORM) semantics. While versioning captures historical versions on overwrites, any version—including a current or previous one—can be permanently deleted at any time by an authorized user. Lifecycle management rules can even automatically purge versions once they exceed an age threshold, so they provide no fixed data-retention guarantee. This makes versioning a convenience for rollback, not a compliance control.
- ✗
Soft delete for blob storage
Why it's wrong here
Soft delete for Azure Storage only preserves deleted blobs for a configurable recovery period (typically 1 to 365 days); it does not prevent deletion from occurring in the first place. During the soft-delete window, data is still physically removed from the active namespace and can be permanently purged after the retention expires. Moreover, soft delete does not protect against overwrites or modifications to active blobs. Thus, it lacks the immutable, tamper-proof guarantee needed for regulatory WORM storage.
- ✓
Immutable blob with time-based retention policy
Why this is correct
A time-based retention policy on an immutable blob container enforces a WORM (write-once, read-many) model, prohibiting any deletion or modification of blobs until the specified retention interval has elapsed. The policy is enforced by Azure Storage and cannot be shortened or removed before expiry, ensuring data meets SEC 17a-4-style compliance requirements. It can be applied at the container level or to individual blob versions, and is protected from administrative tampering. This is the appropriate choice for a fixed retention period.
- ✗
Legal hold on the storage container
Why it's wrong here
A legal hold, while also providing immutability, is designed for indefinite retention during litigation or investigation, not for a fixed retention schedule. Once a legal hold is placed on a container or blob, the data is protected from deletion or modification until the hold is explicitly cleared. Because there is no defined expiration date, it cannot meet a requirement to preserve data for exactly a specified time period. Time-based immutable retention is needed for finite, regulatory-defined retention windows.
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