AZ-900 Describe Azure architecture and services Practice Question
A company stores critical customer data in Azure Blob Storage. The compliance team requires that the data remains available for read operations even if the primary Azure region experiences a complete outage. They plan to use an Azure storage redundancy option that automatically replicates data to a secondary region and allows read access from that secondary region during an outage, without requiring any manual failover action. Which storage redundancy option should they configure on the storage account?
⚠ Common exam trap
A common mix-up: candidates confuse GRS with RA-GRS, assuming that geo-redundancy alone provides automatic read access from the secondary region, but GRS requires a manual failover to enable reads, whereas RA-GRS explicitly enables read access without any manual action.
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)
RA-GRS (Read-access geo-redundant storage) is correct because it replicates data to a secondary region (geo-redundancy) and, crucially, enables read access to that secondary replica during a primary region outage without requiring any manual failover. This meets the compliance requirement for automatic read availability during a complete primary region failure.
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
Locally-redundant storage (LRS) replicates each blob three times within a single datacenter in the primary region. This protects against drive and rack failures, but it provides no redundancy against a datacenter-wide outage or a regional disaster. Because the compliance requirement demands resilience beyond the primary region, LRS fails to meet it.
When this WOULD be correct
When the compliance requirement is only to protect data against local hardware failures within a single datacenter, and cost minimization is the primary goal, LRS is the appropriate choice.
- ✗
Zone-redundant storage (ZRS)
Why it's wrong here
Zone-redundant storage (ZRS) synchronously replicates data across three Azure availability zones within the primary region, protecting against individual zone failures. However, it does not copy data to a paired secondary region, so a complete regional outage would still result in data unavailability. Without any geo-redundancy, ZRS cannot satisfy the requirement for automatic read access during a region-wide disaster.
When this WOULD be correct
A company requires high availability within a single Azure region, protecting against datacenter-level failures (e.g., due to zone outages), but does not need cross-region disaster recovery. ZRS would be correct if the requirement is to withstand zone failures without multi-region replication.
- ✗
Geo-redundant storage (GRS)
Why it's wrong here
GRS replicates data to a paired secondary region for regional disaster recovery, but read access to the secondary region is not enabled by default. To read data from the secondary region during an outage, a manual failover must be initiated, which does not satisfy the requirement for automatic read access.
When this WOULD be correct
A company needs geo-redundancy for disaster recovery but does not require immediate read access from the secondary region during an outage. They are willing to perform a manual failover to restore read access, making GRS the appropriate choice.
- ✓
Read-access geo-redundant storage (RA-GRS)
Why this is correct
RA-GRS replicates data to a paired secondary region and provides read-only access to the secondary endpoint at all times. During a primary region outage, data can still be read from the secondary region without any manual action, meeting the compliance requirement.
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 replicates data to a paired secondary region and provides read-only access to the secondary endpoint at all times. During a primary region outage, data can still be read from the secondary region without any manual action, meeting the compliance requirement.
✗Locally-redundant storage (LRS)Wrong answer — click to see why▾
Why this is wrong here
LRS stores data only within a single datacenter in the primary region, providing no protection against a regional outage, so it cannot ensure read availability during a complete primary region failure.
★ When this WOULD be the correct answer
When the compliance requirement is only to protect data against local hardware failures within a single datacenter, and cost minimization is the primary goal, LRS is the appropriate choice.
Why candidates choose this
Candidates may mistakenly believe that LRS offers some level of regional redundancy due to the term 'redundant', or they may overlook the requirement for read access during a regional outage.
✗Zone-redundant storage (ZRS)Wrong answer — click to see why▾
Why this is wrong here
ZRS replicates data synchronously across availability zones within a single region, not to a secondary region. It does not provide read access during a primary region outage because there is no secondary region to fail over to.
★ When this WOULD be the correct answer
A company requires high availability within a single Azure region, protecting against datacenter-level failures (e.g., due to zone outages), but does not need cross-region disaster recovery. ZRS would be correct if the requirement is to withstand zone failures without multi-region replication.
Why candidates choose this
Candidates may confuse 'zone' with 'region' and think ZRS provides cross-region redundancy, or they may assume that 'zone-redundant' implies protection against regional outages similar to geo-redundancy.
✗Geo-redundant storage (GRS)Wrong answer — click to see why▾
Why this is wrong here
GRS replicates data to a secondary region but does not provide read access to that secondary region during an outage unless a manual failover is initiated. The question requires automatic read access without manual action, which is only provided by RA-GRS.
★ When this WOULD be the correct answer
A company needs geo-redundancy for disaster recovery but does not require immediate read access from the secondary region during an outage. They are willing to perform a manual failover to restore read access, making GRS the appropriate choice.
Why candidates choose this
Candidates may confuse GRS with RA-GRS, assuming that geo-replication inherently includes read access to the secondary region, or they may overlook the specific requirement for automatic read access without manual failover.
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
Blob
A blob is a large piece of unstructured data, like a photo or video, stored in the cloud with a unique identifier.
About these practice questions
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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.