Azure Blob Storage Cool vs Archive Tier
You plan to store backup files that are written once per week and are rarely accessed except during an audit. The company wants the lowest storage cost but still needs online access within hours, not days. Which blob access tier should you choose?
Quick Answer
The answer is the Cool tier. This is the correct choice because Cool tier is designed for data that is infrequently accessed and stored for at least 30 days, offering significantly lower storage costs than Hot tier while still providing millisecond latency for online access. Since the backup files are written once per week and rarely accessed except during an audit, Cool tier meets the requirement of online access within hours at the lowest storage cost among the online tiers; Archive tier would be cheaper for storage but requires rehydration taking up to 15 hours, which violates the “within hours” constraint. On the AZ-104 exam, this scenario tests your ability to distinguish between access frequency, retrieval time, and cost trade-offs across Hot, Cool, and Archive tiers—a common trap is choosing Archive for its low storage cost without considering the rehydration delay. Remember the memory tip: “Cool for occasional, Archive for frozen.”
⚠ Common exam trap
Test-takers frequently choose Archive for the lowest storage cost without considering the rehydration time requirement, mistakenly assuming 'online access within hours' is satisfied by Archive's standard rehydration priority of up to 15 hours.
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
✓
Cool
The Cool tier is the correct choice because it is designed for data that is infrequently accessed and stored for at least 30 days, offering lower storage costs than Hot while still providing millisecond latency for online access. Since backups are written once per week and rarely accessed except during an audit, Cool tier meets the requirement of online access within hours at the lowest storage cost among the online 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
Why it's wrong here
Hot is optimized for frequent access and usually costs more for storage.
When this WOULD be correct
A question where data is accessed frequently (e.g., multiple times per day) and low latency is critical, such as a production database backup that is restored often. The requirement would be lowest latency, not lowest cost.
- ✓
Cool
Why this is correct
Cool is appropriate for infrequently accessed data that still needs to remain online.
- ✗
Archive
Why it's wrong here
Archive has the lowest storage cost but requires rehydration and is not online for normal access.
When this WOULD be correct
If the question stated that data is rarely accessed and retrieval within 24-48 hours is acceptable, or if the requirement was lowest storage cost with no specific online access time constraint, Archive would be correct.
- ✗
Premium
Why it's wrong here
Premium is for workloads requiring low latency and high IOPS, not low-cost backup retention.
When this WOULD be correct
A question where the workload requires consistent, low-latency access (e.g., <10ms) for frequently updated data, such as an interactive application's active dataset, and cost is not the primary concern.
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-104 exam frequently reuses these exact scenarios with slightly different constraints.
✓CoolCorrect answer▾
Why this is correct
Cool is appropriate for infrequently accessed data that still needs to remain online.
✗HotWrong answer — click to see why▾
Why this is wrong here
Hot tier is designed for frequently accessed data with the lowest access latency, but it has the highest storage cost. The scenario requires lowest storage cost and only occasional access, making Hot unnecessarily expensive.
★ When this WOULD be the correct answer
A question where data is accessed frequently (e.g., multiple times per day) and low latency is critical, such as a production database backup that is restored often. The requirement would be lowest latency, not lowest cost.
Why candidates choose this
Candidates may assume 'online access within hours' means Hot is needed, but Cool also provides online access within hours at lower cost. They overlook that Hot is for frequent access, not just online availability.
✗ArchiveWrong answer — click to see why▾
Why this is wrong here
Archive tier has the lowest storage cost but retrieval times can take up to 15 hours, which does not meet the requirement of online access within hours.
★ When this WOULD be the correct answer
If the question stated that data is rarely accessed and retrieval within 24-48 hours is acceptable, or if the requirement was lowest storage cost with no specific online access time constraint, Archive would be correct.
Why candidates choose this
Candidates see 'lowest storage cost' and 'rarely accessed' and immediately think Archive, overlooking the 'online access within hours' constraint that Archive cannot satisfy.
✗PremiumWrong answer — click to see why▾
Why this is wrong here
Premium tier is designed for low-latency, high-performance workloads and has the highest cost, which contradicts the requirement for lowest storage cost. The scenario does not need sub-second access, only online access within hours.
★ When this WOULD be the correct answer
A question where the workload requires consistent, low-latency access (e.g., <10ms) for frequently updated data, such as an interactive application's active dataset, and cost is not the primary concern.
Why candidates choose this
Candidates may assume 'Premium' implies better overall performance and reliability, not realizing it is optimized for specific high-cost, low-latency scenarios and is not suitable for cost-sensitive backup storage.
Analysis generated from the official AZ-104blueprint 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
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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
Cool tier
Cool tier is a low-cost, online-only storage access tier in Microsoft Azure Blob Storage designed for data that is infrequently accessed and stored for at least 30 days.
About these practice questions
Courseiva writes every AZ-104 question from scratch — 1,049 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on AZ-104
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A compliance team keeps signed contract scans in blob storage. The files are usually not accessed, but when they are needed they must be available immediately without waiting for rehydration. The team wants the lowest-cost online tier that still allows immediate reads. Which access tier should you choose?
medium- A.Hot
- B.Cool
- ✓ C.Cold
- D.Archive
Why C: The Cold tier (C) is correct because it is the lowest-cost online access tier that provides immediate read access without requiring rehydration. Unlike the Archive tier, Cold tier data is always online and can be read instantly, while still offering lower storage costs than Cool or Hot tiers for data that is rarely accessed.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-104 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-104 exam.