AZ-900 Describe Azure architecture and services Practice Question
A company has a large dataset of historical financial records that must be retained for 10 years to comply with regulatory requirements. The data is accessed only a few times per year during audits. When accessed, a retrieval delay of up to 15 hours is acceptable. The company wants to minimize storage costs for this dataset. Which Azure Blob storage access tier should the company use?
⚠ Common exam trap
Watch out — candidates often choose Cool tier because they see 'rarely accessed' and think Cool is sufficient, but they overlook the 10-year retention and the fact that Archive is specifically designed for data that is accessed only a few times per year with acceptable retrieval delays, offering the lowest cost.
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 data that is rarely accessed and has a flexible retrieval time. With a 10-year retention requirement and only a few accesses per year, the Archive tier's retrieval time of up to 15 hours (actual range is 1–15 hours for standard retrieval) is acceptable, and it minimizes storage costs compared to other 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.
- ✗
Hot tier
Why it's wrong here
The Hot tier is designed for data that is accessed or modified frequently, such as active files, and its pricing reflects that with higher per-GB storage costs than Cool or Archive. Although retrieval is immediate, the company tolerates a delay of up to 15 hours, so the low latency provides no value; what matters is minimizing cost for an access pattern of only a few times per year. Since archival data sits idle most of the time, Hot's storage fees would unnecessarily inflate the company's Azure bill.
When this WOULD be correct
A company needs to store data that is accessed frequently (multiple times per day) and requires low latency (milliseconds) for real-time applications, such as serving images on a website or streaming video content.
- ✗
Cool tier
Why it's wrong here
The Cool tier is for infrequently accessed data with lower storage costs than Hot, but it still charges higher storage fees than Archive and has lower retrieval latency. It is not the cheapest option given the very rare access pattern.
When this WOULD be correct
A company has data that is accessed infrequently (e.g., monthly) but requires immediate retrieval (within seconds). The data must be stored for a medium term (e.g., 90 days) and cost savings over Hot tier are desired.
- ✓
Archive tier
Why this is correct
The Archive tier offers the lowest storage costs and is designed for long-term retention of data that is rarely accessed. Retrieval times are measured in hours (up to 15 hours), which matches the company's acceptable delay. This is the most cost-effective choice.
- ✗
Premium tier
Why it's wrong here
The Premium tier is engineered for sub-second latency and high transaction rates, backed by SSDs and optimized for active, interactive workloads such as streaming or high-frequency read/write applications. Its storage and operation costs are significantly higher than Archive's, and it offers no benefit for data that will be written once and read a few times per year. Thus, using Premium for this historical financial dataset would result in excessive cost without any retrieval performance advantage.
When this WOULD be correct
A company requires sub-millisecond latency for frequently accessed data, such as for an interactive real-time application or an online transaction processing (OLTP) system, and is willing to pay higher costs for performance.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Archive tierCorrect answer▾
Why this is correct
The Archive tier offers the lowest storage costs and is designed for long-term retention of data that is rarely accessed. Retrieval times are measured in hours (up to 15 hours), which matches the company's acceptable delay. This is the most cost-effective choice.
✗Hot tierWrong answer — click to see why▾
Why this is wrong here
The Hot tier is designed for frequently accessed data with low latency requirements, but this dataset is accessed only a few times per year and a 15-hour retrieval delay is acceptable, making Hot tier unnecessarily expensive.
★ When this WOULD be the correct answer
A company needs to store data that is accessed frequently (multiple times per day) and requires low latency (milliseconds) for real-time applications, such as serving images on a website or streaming video content.
Why candidates choose this
Candidates may assume that all data should be stored in the Hot tier for quick access, overlooking the cost savings of lower tiers when access frequency is low and latency is acceptable.
✗Cool tierWrong answer — click to see why▾
Why this is wrong here
The Cool tier offers lower storage cost than Hot but higher retrieval costs and faster access than Archive. However, the data is accessed only a few times per year with a 15-hour retrieval delay acceptable, making the Archive tier cheaper overall.
★ When this WOULD be the correct answer
A company has data that is accessed infrequently (e.g., monthly) but requires immediate retrieval (within seconds). The data must be stored for a medium term (e.g., 90 days) and cost savings over Hot tier are desired.
Why candidates choose this
Candidates may think 'infrequent access' automatically means Cool tier, without considering that the acceptable retrieval delay of 15 hours allows the even cheaper Archive tier.
✗Premium tierWrong answer — click to see why▾
Why this is wrong here
The Premium tier is designed for low-latency, high-performance scenarios and is the most expensive tier, which contradicts the requirement to minimize storage costs for infrequently accessed data with a 15-hour retrieval delay.
★ When this WOULD be the correct answer
A company requires sub-millisecond latency for frequently accessed data, such as for an interactive real-time application or an online transaction processing (OLTP) system, and is willing to pay higher costs for performance.
Why candidates choose this
Candidates may mistakenly think 'Premium' implies better overall value or assume it is suitable for all data, overlooking that it is cost-prohibitive for archival data with minimal access needs.
Analysis generated from the official AZ-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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
Dataset
A dataset is a collection of related data, usually in a structured format, that can be used for analysis, training models, or reporting in Azure data services.
About these practice questions
This AZ-900 question is part of Courseiva's 981-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
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.