AZ-900 Describe Azure architecture and services Practice Question
A company uses Azure Blob Storage to store archival backups of financial records. The company requires that the data is protected against a complete regional outage by replicating it to another Azure region. However, they do not need to access the replicated copy unless the primary region fails. The company wants to minimize storage costs while meeting this requirement. Which type of storage replication should the company configure?
⚠ Common exam trap
Watch out — candidates often confuse GRS with RA-GRS, assuming that geo-replication automatically provides read access to the secondary copy, but RA-GRS is a separate, more expensive SKU that enables continuous read access, which is not required when you only need failover capability.
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
✓
Geo-redundant storage (GRS)
Geo-redundant storage (GRS) replicates your data synchronously three times within the primary region using LRS, then asynchronously to a secondary region hundreds of miles away. This meets the requirement of protecting against a complete regional outage while minimizing costs, because the secondary copy is not accessible for reads unless Microsoft initiates a failover, and GRS is less expensive than RA-GRS which includes read-access to the secondary region.
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 data center in the primary region. This protects against server rack and drive failures but does not protect against a regional outage, so it does not meet the requirement.
When this WOULD be correct
LRS would be correct if the question required the lowest-cost replication option and the company could tolerate data loss from a regional disaster, or if the data could be easily recreated from another source.
- ✓
Geo-redundant storage (GRS)
Why this is correct
GRS replicates data asynchronously to a paired secondary region. It provides protection against a complete regional outage without offering read access to the secondary copy, which keeps costs lower than RA-GRS. This meets the company's requirement.
- ✗
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, ensuring durability against datacenter-level failures such as rack or drive losses. However, because all replicas reside in the same geographic region, ZRS does not provide any protection against a region-wide outage, which a disaster recovery strategy would require. Thus, it fails the company's need for a secondary-region failover capability while preserving cost efficiency.
When this WOULD be correct
ZRS would be correct if the question required high availability within a single region (e.g., protecting against datacenter failures) and the company did not need cross-region disaster recovery, but still wanted synchronous replication for durability.
- ✗
Read-access geo-redundant storage (RA-GRS)
Why it's wrong here
RA-GRS replicates to a secondary region like GRS, but it also provides read access to the secondary copy. This incurs additional cost (due to the read access functionality). Since the company does not need read access unless the primary fails, GRS is the more cost-effective option.
When this WOULD be correct
A company needs to replicate data to another region for disaster recovery and also requires read-only access to the secondary region for reporting or analytics during normal operations, even though the primary region is available.
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.
✓Geo-redundant storage (GRS)Correct answer▾
Why this is correct
GRS replicates data asynchronously to a paired secondary region. It provides protection against a complete regional outage without offering read access to the secondary copy, which keeps costs lower than RA-GRS. This meets the company's requirement.
✗Locally redundant storage (LRS)Wrong answer — click to see why▾
Why this is wrong here
LRS only replicates data within a single datacenter in the primary region, so it does not protect against a complete regional outage, which is a key requirement in the question.
★ When this WOULD be the correct answer
LRS would be correct if the question required the lowest-cost replication option and the company could tolerate data loss from a regional disaster, or if the data could be easily recreated from another source.
Why candidates choose this
Candidates may choose LRS because it is the cheapest option and they overlook the requirement for regional outage protection, focusing only on minimizing costs.
✗Zone-redundant storage (ZRS)Wrong answer — click to see why▾
Why this is wrong here
ZRS replicates data synchronously across three Azure availability zones within a single region, not across regions. It does not protect against a complete regional outage, which requires geo-replication to a secondary region.
★ When this WOULD be the correct answer
ZRS would be correct if the question required high availability within a single region (e.g., protecting against datacenter failures) and the company did not need cross-region disaster recovery, but still wanted synchronous replication for durability.
Why candidates choose this
Candidates may confuse 'zone' with 'region' or think ZRS provides cross-region protection because it involves multiple zones, not realizing zones are within one region.
✗Read-access geo-redundant storage (RA-GRS)Wrong answer — click to see why▾
Why this is wrong here
RA-GRS provides read access to the secondary region, which is not required because the company only needs access during a primary region failure. This adds unnecessary cost compared to GRS.
★ When this WOULD be the correct answer
A company needs to replicate data to another region for disaster recovery and also requires read-only access to the secondary region for reporting or analytics during normal operations, even though the primary region is available.
Why candidates choose this
Candidates may confuse RA-GRS with GRS, thinking the extra read access is beneficial, but overlook that the question explicitly states they do not need to access the replicated copy unless the primary fails, making RA-GRS costlier than necessary.
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
Geo-redundant storage
Geo-redundant storage is a data storage strategy that automatically copies and maintains data in at least two geographically separated locations to protect against regional disasters and ensure high availability.
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.