The answer is Zone-Redundant Storage (ZRS). ZRS is the correct choice because it synchronously replicates your data across three distinct Azure availability zones within a single region, meaning every write is committed to all three zones before the operation is acknowledged, providing strong consistency and resilience against an entire zone failure. On the Microsoft Azure Fundamentals AZ-900 exam, this question tests your understanding of the core redundancy options, often contrasting ZRS with Locally-Redundant Storage (LRS), which only replicates within a single data center, or Geo-Redundant Storage (GRS), which adds asynchronous replication to a secondary region. A common trap is confusing ZRS with GRS, but remember that ZRS is strictly regional and synchronous, while GRS involves a separate paired region. For a quick memory tip, think of ZRS as “Zone-Ready Sync” — three zones, all written at the same time.
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 synchronously across three 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 high durability and availability even if an entire zone fails. This meets the exact requirement of the question: synchronous replication across multiple zones in one 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 datacenter, not across availability zones.
✓
Zone-Redundant Storage (ZRS)
Why this is correct
ZRS replicates data synchronously across three availability zones in one region.
Related concept
Read the scenario before looking for a memorised answer.
✗
Geo-Redundant Storage (GRS)
Why it's wrong here
GRS replicates to a secondary region but not necessarily across availability zones in the primary.
✗
Geo-Zone-Redundant Storage (GZRS)
Why it's wrong here
GZRS combines zone redundancy in the primary region with geo-replication to a secondary region.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse ZRS with LRS, thinking LRS provides zone-level redundancy, but LRS only replicates within a single datacenter and does not protect against zone failures.
Detailed technical explanation
How to think about this question
ZRS uses synchronous replication at the storage layer, writing data to three separate availability zones before acknowledging a write, which provides a Recovery Point Objective (RPO) of zero and a Recovery Time Objective (RTO) of minutes. Under the hood, Azure Storage partitions data into chunks and distributes replicas across fault domains in each zone, ensuring that a zone-level outage (e.g., power or network failure) does not compromise data durability. In a real-world scenario, a retail application requiring high availability during a regional disaster would benefit from ZRS to maintain uptime without relying on geo-replication.
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 high durability and availability even if an entire zone fails. This meets the exact requirement of the question: synchronous replication across multiple zones in one 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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