AZ-900 Describe Azure architecture and services Practice Question
A company needs to store and analyze large amounts of unstructured log data at low cost. Which Azure storage solution is MOST appropriate?
⚠ Common exam trap
Watch out — candidates often confuse Azure Table Storage (a NoSQL key-value store) with a cost-effective solution for unstructured data, but it is actually designed for semi-structured data and lacks the low-cost tiering and append capabilities of Blob Storage for log analytics.
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 cool tier
Azure Blob Storage with cool tier is the most appropriate solution because it is optimized for storing large amounts of unstructured log data at low cost. The cool tier offers lower storage costs than the hot tier, making it ideal for infrequently accessed data like logs, while still providing high durability and scalability. Blob Storage natively supports unstructured data such as text logs, binary files, and streaming data, which aligns perfectly with the requirement.
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 SQL Database
Why it's wrong here
Azure SQL Database is a fully managed relational DBMS that enforces schemas, relationships, ACID transactions, and rich indexing for structured business data, all of which create overhead per record on mass ingestion of varied log messages. Its pricing is based on reserved DTUs/vCores plus predictable per-GB storage, which becomes prohibitively expensive for gigabytes to terabytes of unstructured log data while also requiring data-shaping transforms before writes. For this workload, it offers none of the cost advantages of object-tier storage and is therefore clearly wrong.
- ✗
Azure Table Storage
Why it's wrong here
Azure Table Storage is a schemaless NoSQL key-value store built for fast point-queries using partition and row keys, typically powering live application state with predictable low latency. It is not suited to large-scale analytics or archival log storage because queries outside the key structure are inefficient, there is no built-in tiering from hot to archive for cost reduction, and capacity costs add up when storing high-volume telemetry. Therefore, while it can hold semi-structured records, it does not match the cost model or analytical access patterns required here.
- ✓
Azure Blob Storage with cool tier
Why this is correct
Azure Blob Storage is a massively scalable object store designed for unstructured data, such as application logs, telemetry, and backup files, with no fixed schema limiting ingestion. The cool access tier specifically lowers storage price for data that is infrequently accessed yet needs to be retained for long periods, charging higher per-GB access but making bulk log retention far cheaper than hot or transactional stores. This combination of virtually unlimited capacity, REST-based ingestion, and tiered cost optimization is exactly why it is the correct answer.
- ✗
Azure Files
Why it's wrong here
Azure Files provides managed SMB/NFS file shares that are ideal for migrating on-premises file servers to the cloud, preserving file-level protocols, ACLs, and directory structures. However, it is not optimized for cost-effective large-scale unstructured data storage because file-share billing per GiB is significantly higher than object storage, and it lacks the tiered hot/cool/archive lifecycle policies that make Blob Storage economical for log archives. Thus, for mass log ingestion, it is the wrong choice.
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 |
Go deeper
Related to this question
Learn chapter
Azure Regions and Geographies
Key term
Blob
A blob is a large piece of unstructured data, like a photo or video, stored in the cloud with a unique identifier.
Key term
Scalability
Scalability is the ability of a system, network, or process to handle a growing amount of work by adding resources, either by making the existing resources more powerful (vertical scaling) or by adding more resources (horizontal scaling).
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-900 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-900 exam.