AZ-900 Describe Azure architecture and services Practice Question
A company needs to store log files from multiple applications. The logs are accessed infrequently for compliance audits but must be retained for 10 years. Storage cost must be minimized. Which Azure Storage access tier should they use for the blob storage?
⚠ Common exam trap
It's easy for candidates to confuse the Cold tier (which is still for infrequent access but not archival) with the Archive tier, or they assume the Cool tier is sufficient for long-term retention without considering that the Archive tier is the only one designed to minimize storage cost for data that is accessed less than once a year.
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 designed for data that is rarely accessed and has a flexible retrieval latency of up to 15 hours, making it ideal for compliance logs that are accessed infrequently but must be retained for 10 years. It offers the lowest storage cost among all Azure Blob Storage access tiers, which directly minimizes storage costs for long-term retention. The Hot, Cool, and Cold tiers are progressively more expensive and are optimized for more frequent access patterns, not for archival scenarios.
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
Hot tier is optimized for data with high access frequency and requires the highest storage cost among the tiers. For log files that are only sporadically retrieved, paying for Hot's low-latency performance and premium storage pricing is wasteful. The scenario does not demand immediate access, so Archive's lower cost and longer rehydration time are more appropriate. Hot tier is therefore an incorrect and unnecessarily expensive choice.
When this WOULD be correct
A company needs to store log files that are accessed frequently (e.g., daily) for real-time monitoring and analysis, with a short retention period (e.g., 30 days). The priority is low latency and high throughput, not cost minimization.
- ✗
Cool tier
Why it's wrong here
Cool tier is designed for data that is infrequently accessed and held for at least 30 days, offering lower storage cost than Hot but higher than Archive. However, for log files that are only occasionally accessed, Cool's storage pricing remains significantly above Archive, and its default access latency, while faster, is unnecessary for a use case where high retrieval latency is acceptable. Therefore, Cool tier is not the most cost-effective choice for long-term log retention.
- ✗
Cold tier
Why it's wrong here
Cold tier is meant for data that is accessed occasionally but must be kept for long periods, and it has a lower storage cost than Cool but a higher one than Archive. It requires a minimum retention period of 90 days and provides millisecond latency, which is not needed for this log-retention scenario. Because Archive is even cheaper per gigabyte and the logs are accessed so rarely, the storage savings from Archive make Cold the wrong choice.
When this WOULD be correct
A company needs to store data that is accessed occasionally (e.g., monthly) and retained for a few months to a year, with a requirement for lower cost than Cool but faster retrieval than Archive.
- ✓
Archive tier
Why this is correct
Archive tier provides the lowest per-gigabyte storage cost of all Azure Blob access tiers, making it the optimal choice for retaining log files that are rarely accessed. Data remains offline, and rehydration can take up to 15 minutes, but this high-latency access pattern is perfectly acceptable for logs that are only retrieved occasionally. Additionally, Archive has a 180-day minimum retention period, which aligns well with long-term archiving of application logs. This combination of minimal cost and tolerable latency makes Archive the correct tier.
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
Archive tier provides the lowest per-gigabyte storage cost of all Azure Blob access tiers, making it the optimal choice for retaining log files that are rarely accessed. Data remains offline, and rehydration can take up to 15 minutes, but this high-latency access pattern is perfectly acceptable for logs that are only retrieved occasionally. Additionally, Archive has a 180-day minimum retention period, which aligns well with long-term archiving of application logs. This combination of minimal cost and tolerable latency makes Archive the correct tier.
✗Hot tierWrong answer — click to see why▾
Why this is wrong here
The Hot tier is designed for frequently accessed data and has the highest storage cost, which contradicts the requirement to minimize storage costs for infrequently accessed logs retained for 10 years.
★ When this WOULD be the correct answer
A company needs to store log files that are accessed frequently (e.g., daily) for real-time monitoring and analysis, with a short retention period (e.g., 30 days). The priority is low latency and high throughput, not cost minimization.
Why candidates choose this
Candidates may assume 'Hot' is the default or safest choice without considering cost implications, or they may overlook the specific access pattern and retention period described in the question.
✗Cold tierWrong answer — click to see why▾
Why this is wrong here
The Cold tier has a minimum retention period of 30 days and higher storage costs than Archive, making it unsuitable for 10-year retention with infrequent access where cost minimization is key.
★ When this WOULD be the correct answer
A company needs to store data that is accessed occasionally (e.g., monthly) and retained for a few months to a year, with a requirement for lower cost than Cool but faster retrieval than Archive.
Why candidates choose this
Candidates may confuse 'Cold' with 'Archive' due to similar names, or think that Cold is the cheapest tier for long-term storage without considering the even lower cost of Archive for infrequent access.
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 storage
Blob storage is a cloud service for storing large amounts of unstructured data, such as text or binary data, like documents, images, and videos.
Key term
Azure Storage
Azure Storage is Microsoft's cloud-based service for storing data like files, messages, and backups with high durability and scalability.
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.