AZ-900 Describe Azure architecture and services Practice Question
A company uses Azure Blob Storage to store backup files that must survive a complete regional outage. The company needs the data to be automatically accessible from a secondary region if the primary region becomes unavailable, without any manual failover. Which storage redundancy option should the company use?
⚠ Common exam trap
It's easy for candidates to choose GRS (Option C) because they know it provides geo-replication, but they overlook the 'without any manual failover' requirement, which only RA-GRS satisfies by offering automatic read access to the secondary region.
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
✓
Read-Access Geo-Redundant Storage (RA-GRS)
Read-Access Geo-Redundant Storage (RA-GRS) is the correct choice because it provides geo-redundancy (data replicated to a secondary region for disaster recovery) and, crucially, enables read access to the secondary region without requiring a manual failover. This ensures that if the primary region becomes unavailable, the data is automatically accessible from the secondary region for read operations, meeting the requirement of no manual intervention.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Locally Redundant Storage (LRS)
Why it's wrong here
LRS replicates data three times within a single datacenter. It protects against server rack and drive failures but not against a full datacenter or regional outage. Therefore, it does not meet the requirement for surviving a complete regional outage.
When this WOULD be correct
If the question specifies that the data must survive a single datacenter failure within a region and cost is the primary concern, LRS would be the correct choice.
- ✗
Zone-Redundant Storage (ZRS)
Why it's wrong here
ZRS replicates data synchronously across three Azure availability zones within a primary region. It protects against a zone failure but not against a full regional outage. Data is not replicated to a secondary region, so it does not satisfy the requirement.
When this WOULD be correct
A company needs to protect against datacenter-level failures within a single region, such as a fire or flood affecting one availability zone, and requires automatic failover without manual intervention. ZRS would be the correct choice in that scenario.
- ✗
Geo-Redundant Storage (GRS)
Why it's wrong here
GRS replicates data to a paired secondary region, providing resilience against a regional outage. However, to access data in the secondary region, a customer must initiate a manual failover (or rely on Microsoft-managed failover for rare events). The question specifies 'without any manual failover,' so GRS alone does not meet the requirement.
When this WOULD be correct
A company needs to store backup files that must survive a complete regional outage and is willing to perform a manual failover to access the data from the secondary region. The company does not require automatic read access from the secondary region.
- ✓
Read-Access Geo-Redundant Storage (RA-GRS)
Why this is correct
RA-GRS is identical to GRS in replication (data is copied to a secondary region), but it additionally enables read access to the secondary region at all times. If the primary region fails, data is automatically readable from the secondary endpoint without any manual failover steps, exactly matching the requirement. (The same logic applies to RA-GZRS for zone-redundant geo-replication.)
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.
✓Read-Access Geo-Redundant Storage (RA-GRS)Correct answer▾
Why this is correct
RA-GRS is identical to GRS in replication (data is copied to a secondary region), but it additionally enables read access to the secondary region at all times. If the primary region fails, data is automatically readable from the secondary endpoint without any manual failover steps, exactly matching the requirement. (The same logic applies to RA-GZRS for zone-redundant geo-replication.)
✗Locally Redundant Storage (LRS)Wrong answer — click to see why▾
Why this is wrong here
LRS replicates data three times within a single datacenter in the primary region, so it cannot survive a complete regional outage.
★ When this WOULD be the correct answer
If the question specifies that the data must survive a single datacenter failure within a region and cost is the primary concern, LRS would be the correct choice.
Why candidates choose this
Candidates may confuse local redundancy with sufficient protection, not realizing that a regional outage affects all datacenters in that region.
✗Zone-Redundant Storage (ZRS)Wrong answer — click to see why▾
Why this is wrong here
Zone-Redundant Storage (ZRS) replicates data synchronously across three Azure availability zones within a single region, but does not provide protection against a complete regional outage.
★ When this WOULD be the correct answer
A company needs to protect against datacenter-level failures within a single region, such as a fire or flood affecting one availability zone, and requires automatic failover without manual intervention. ZRS would be the correct choice in that scenario.
Why candidates choose this
Candidates may confuse 'zone' with 'region' and think ZRS provides cross-region redundancy, or they may not fully understand that ZRS is limited to a single region.
✗Geo-Redundant Storage (GRS)Wrong answer — click to see why▾
Why this is wrong here
Geo-Redundant Storage (GRS) replicates data to a secondary region for durability, but it does not provide automatic read access from the secondary region without a manual failover. The question requires automatic accessibility from the secondary region, which only RA-GRS offers.
★ When this WOULD be the correct answer
A company needs to store backup files that must survive a complete regional outage and is willing to perform a manual failover to access the data from the secondary region. The company does not require automatic read access from the secondary region.
Why candidates choose this
Candidates may confuse GRS with RA-GRS, assuming that geo-replication automatically provides read access from the secondary region, or they may overlook the 'automatic accessibility' requirement in the question.
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
Region
A region is a distinct geographic location where a cloud provider operates multiple data centers that are connected by low-latency networks and provide cloud services.
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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.