The answer is Zone-Redundant Storage (ZRS). This is the correct Azure storage redundancy option because it synchronously replicates your data across three distinct Azure availability zones within a single region, meaning your data remains durable and accessible even if an entire zone—including all its physical data centers—goes offline. On the Microsoft Azure Fundamentals AZ-900 exam, this question tests your understanding of how Azure balances high availability and cost; a common trap is confusing ZRS with Locally Redundant Storage (LRS), which only replicates within a single data center, or Geo-Redundant Storage (GRS), which replicates to a separate region. To remember it, think of the "Z" in ZRS as standing for "Zone"—it keeps your data safe across multiple zones in one region, not across the globe.
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.
Which Azure storage redundancy option replicates data across multiple availability zones within a single region?
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) is the correct answer because it synchronously replicates data across three Azure availability zones within a single region, ensuring durability even if an entire zone fails. This provides higher availability than LRS (which replicates within a single data center) and lower latency than GRS/RA-GRS (which replicate to a secondary 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 stores three copies within a single data center, not across availability zones.
✗
Geo-Redundant Storage (GRS)
Why it's wrong here
GRS replicates to a paired region, not across availability zones within one region.
✓
Zone-Redundant Storage (ZRS)
Why this is correct
ZRS replicates synchronously across three availability zones within a single region.
Related concept
Read the scenario before looking for a memorised answer.
✗
Read-Access Geo-Redundant Storage (RA-GRS)
Why it's wrong here
RA-GRS provides geo-replication with read access in a paired region, not AZ replication.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'zone' with 'region' and incorrectly choose GRS or RA-GRS, thinking that 'redundancy across zones' means across regions, or they pick LRS because they assume 'local' implies zone-level redundancy.
Detailed technical explanation
How to think about this question
Under the hood, ZRS uses synchronous replication to three separate availability zones, each with independent power, cooling, and networking infrastructure, providing a Recovery Point Objective (RPO) of zero and a Recovery Time Objective (RTO) of minutes for most scenarios. In a real-world scenario, if an application requires high availability within a region (e.g., for compliance or low-latency reads) and cannot tolerate the latency of cross-region replication, ZRS is the optimal choice over GRS or RA-GRS.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
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) is the correct answer because it synchronously replicates data across three Azure availability zones within a single region, ensuring durability even if an entire zone fails. This provides higher availability than LRS (which replicates within a single data center) and lower latency than GRS/RA-GRS (which replicate to a secondary 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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Question Discussion
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