Question 173 of 1,031

Describe Azure architecture and services →mediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is Zone-redundant storage (ZRS). ZRS synchronously replicates data across three Azure availability zones within the same region, so if an entire zone fails, your data remains intact with zero data loss—exactly meeting the requirement for intra-region resilience without cross-region replication. On the AZ-900 exam, this scenario tests your ability to distinguish between redundancy options based on replication scope and synchronicity; a common trap is confusing ZRS with GRS, which replicates to a secondary region asynchronously. Remember that ZRS keeps everything local but spreads it across zones, while LRS only uses a single zone and risks data loss during a zone outage. For a quick memory tip: think “ZRS = Zone = Zero data loss within the region.”

AZ-900 Describe Azure architecture and services Practice Question

This AZ-900 practice question tests your understanding of describe azure architecture and services. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A company runs a critical transaction-processing application on Azure virtual machines in the East US region. The application writes data to Azure managed disks and also stores files in Azure Blob Storage. The company's disaster recovery policy requires that all storage data must survive a complete failure of an Azure availability zone within the same region without any data loss. The solution must use synchronous replication and must not replicate data to a different Azure region. Which Azure storage redundancy option should the company configure for the Blob Storage account?

Question 1mediummultiple choice

Full question →

A
Locally redundant storage (LRS)
Why wrong: LRS replicates data three times within a single physical location in the primary region. This protects against server rack and drive failures, but not against a failure of an entire availability zone, because all replicas reside in the same datacenter.
B
Zone-redundant storage (ZRS)
ZRS replicates data synchronously across three Azure availability zones within the primary region. This ensures that if one zone fails, the data remains available and durable from the other zones, meeting the requirement for zone-level protection without cross-region replication.
C
Geo-redundant storage (GRS)
Why wrong: GRS asynchronously replicates data from the primary region to a secondary region hundreds of miles away. While this provides disaster recovery across regions, it does not meet the requirement to remain within the same region, and the asynchronous replication means there could be some data loss if a regional disaster occurs.
D
Read-access geo-redundant storage (RA-GRS)
Why wrong: RA-GRS is identical to GRS but additionally provides read access to the data in the secondary region. It also uses asynchronous replication and replicates to a different region, which does not fulfill the stated requirement of staying within the same region and using synchronous replication.

Full breakdown with real-world context →

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

✓

Zone-redundant storage (ZRS)

Zone-redundant storage (ZRS) synchronously replicates data across three Azure availability zones within the same region, ensuring no data loss if an entire zone fails. This meets the disaster recovery requirement for synchronous replication and intra-region resilience without replicating to a different region.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

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 physical location in the primary region. This protects against server rack and drive failures, but not against a failure of an entire availability zone, because all replicas reside in the same datacenter.
✓
Zone-redundant storage (ZRS)
Why this is correct
ZRS replicates data synchronously across three Azure availability zones within the primary region. This ensures that if one zone fails, the data remains available and durable from the other zones, meeting the requirement for zone-level protection without cross-region replication.
Related concept
Read the scenario before looking for a memorised answer.
✗
Geo-redundant storage (GRS)
Why it's wrong here
GRS asynchronously replicates data from the primary region to a secondary region hundreds of miles away. While this provides disaster recovery across regions, it does not meet the requirement to remain within the same region, and the asynchronous replication means there could be some data loss if a regional disaster occurs.
✗
Read-access geo-redundant storage (RA-GRS)
Why it's wrong here
RA-GRS is identical to GRS but additionally provides read access to the data in the secondary region. It also uses asynchronous replication and replicates to a different region, which does not fulfill the stated requirement of staying within the same region and using synchronous replication.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often confuse ZRS with LRS, assuming LRS provides zone-level resilience, or mistakenly choose GRS/RA-GRS because they think geo-replication is required for disaster recovery, ignoring the explicit synchronous and intra-region constraints.

Detailed technical explanation

How to think about this question

ZRS uses synchronous writes across three availability zones within the same region, leveraging Azure Storage's commit protocol to ensure all copies are updated before acknowledging a write. This provides a Recovery Point Objective (RPO) of zero and a Recovery Time Objective (RTO) of minutes for zone failures, but note that ZRS does not protect against a regional disaster. In real-world scenarios, ZRS is ideal for applications requiring high availability within a region, such as transaction-processing systems that cannot tolerate even seconds of data loss.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this AZ-900 question test?

Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Zone-redundant storage (ZRS) — Zone-redundant storage (ZRS) synchronously replicates data across three Azure availability zones within the same region, ensuring no data loss if an entire zone fails. This meets the disaster recovery requirement for synchronous replication and intra-region resilience without replicating to a different region.

What should I do if I get this AZ-900 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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