AZ-900 Describe Azure architecture and services Practice Question
A company stores critical financial data in Azure Blob Storage. The data must remain available even if an entire Azure region becomes unavailable. Additionally, the company needs the ability to read the data from the secondary region immediately during a regional outage, without waiting for Microsoft to initiate a failover. Which storage redundancy option should the company configure?
⚠ Common exam trap
Many candidates confuse GRS with RA-GRS, assuming that geo-redundancy alone provides immediate read access, but GRS only allows reads after a Microsoft-initiated failover, not instantly during an outage.
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 replicates data to a secondary region (geo-redundancy) and allows immediate read access to that secondary copy during a regional outage, without waiting for Microsoft to initiate a failover. This meets both the availability requirement and the need for instant read access from 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 datacenter in a single region. It does not provide any protection against an entire regional outage, as all copies are lost if the datacenter or region fails.
When this WOULD be correct
A company needs to store non-critical data that can be lost in a regional disaster, but requires the lowest cost and highest throughput within a single datacenter.
- ✗
Geo-Redundant Storage (GRS)
Why it's wrong here
GRS replicates data to a paired secondary region, but read access to the secondary region is not available unless Microsoft performs a failover. This does not meet the requirement for immediate read access during an outage.
When this WOULD be correct
A company needs to ensure data durability across regions but does not require immediate read access during an outage; they can wait for Microsoft to failover. For example, a backup storage solution where data is only needed for disaster recovery after failover.
- ✓
Read-Access Geo-Redundant Storage (RA-GRS)
Why this is correct
RA-GRS replicates data to a secondary region and provides read-only access to the data in the secondary region at all times. This allows the company to continue reading data immediately during a regional outage, meeting both the availability and immediate read access requirements.
- ✗
Zone-Redundant Storage (ZRS)
Why it's wrong here
Zone-Redundant Storage (ZRS) synchronously replicates data across three Azure availability zones within the same primary region, providing high availability (99.99%) against datacenter-level failures. Because all copies reside in a single region, ZRS offers no protection or read access during a complete regional outage — the primary endpoint is the only endpoint available. Unlike RA-GRS, there is no secondary read-only endpoint or independent copy in a geographically distant paired region, making immediate read access during a region-wide disaster impossible. Consequently, while ZRS delivers strong durability within a region, it fails the company's requirement for continuous readable availability when an entire region fails.
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 does not require cross-region disaster recovery. ZRS would be the correct choice to ensure data durability and availability across zones in the same region.
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 secondary region and provides read-only access to the data in the secondary region at all times. This allows the company to continue reading data immediately during a regional outage, meeting both the availability and immediate read access requirements.
✗Locally Redundant Storage (LRS)Wrong answer — click to see why▾
Why this is wrong here
LRS only replicates data within a single datacenter, not across regions, so it cannot provide availability during a regional outage.
★ When this WOULD be the correct answer
A company needs to store non-critical data that can be lost in a regional disaster, but requires the lowest cost and highest throughput within a single datacenter.
Why candidates choose this
Candidates may confuse LRS with a basic redundancy option and overlook the requirement for regional failover, assuming any replication is sufficient.
✗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 data unless Microsoft initiates a failover. The question requires immediate read access during an outage, which GRS cannot provide.
★ When this WOULD be the correct answer
A company needs to ensure data durability across regions but does not require immediate read access during an outage; they can wait for Microsoft to failover. For example, a backup storage solution where data is only needed for disaster recovery after failover.
Why candidates choose this
Candidates may confuse GRS with RA-GRS, assuming that geo-replication inherently allows read access, or they may overlook the 'read-access' requirement in the question.
✗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 it does not provide protection against a region-wide outage. The question requires data availability even if an entire region becomes unavailable, which ZRS cannot fulfill.
★ 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 does not require cross-region disaster recovery. ZRS would be the correct choice to ensure data durability and availability across zones in the same region.
Why candidates choose this
Candidates may confuse 'zone' with 'region' or think that ZRS provides multi-region redundancy because it involves multiple zones, but zones are within one region, not across regions.
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
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.
Key term
Availability
Availability is the measure of how often a system or service is operational and accessible when needed, typically expressed as a percentage of uptime.
About these practice questions
Courseiva writes every AZ-900 question from scratch — 981 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 →
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.