The answer is Locally Redundant Storage (LRS), which stores three copies of your data within a single data center in a single region. This works by writing each piece of data to three separate fault domains—typically different server racks and drives—inside that one facility, ensuring durability even if a disk or rack fails. On the Microsoft Azure Fundamentals AZ-900 exam, this question tests your understanding of the trade-offs between cost and protection: LRS is the cheapest option but offers no defense against a full data center outage, making it a common trap for candidates who assume “three copies” means total safety. A helpful memory tip is to think of LRS as “Local” meaning “Limited” to one location—if the building burns down, your data goes with it, so use it only for easily reconstructable data or non-critical workloads.
AZ-900 Describe Azure architecture and services Practice Question
This AZ-900 practice question tests your understanding of describe azure architecture and services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 stores three copies of data within a single data center in 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
✓
Locally Redundant Storage (LRS)
Locally Redundant Storage (LRS) replicates data three times within a single physical data center in a single region. This provides protection against server rack and drive failures but does not protect against a full data center outage. It is the lowest-cost redundancy option and is suitable for scenarios where data can be reconstructed from other sources.
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.
✗
Zone-Redundant Storage (ZRS)
Why it's wrong here
ZRS stores copies across three availability zones (three separate data centers) within a region.
✗
Geo-Redundant Storage (GRS)
Why it's wrong here
GRS replicates data to a secondary region, not just within a single data center.
✓
Locally Redundant Storage (LRS)
Why this is correct
LRS keeps three copies within a single data center in one region — the lowest cost option.
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 replicates to a secondary region and provides read access there — not a single data center option.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse 'zone' (availability zone) with 'data center' and incorrectly choose ZRS, thinking it replicates within a single data center, when in fact ZRS spans multiple data centers (availability zones) within a region.
Detailed technical explanation
How to think about this question
LRS uses a write-across-three-replicas model within a single storage scale unit, ensuring that a write is acknowledged only after all three copies are committed to disk. This provides 11 nines (99.999999999%) durability over a given year, but it is vulnerable to a complete data center loss (e.g., fire, flooding). In practice, LRS is often used for non-critical data or as a building block for higher-level redundancy strategies like GRS, where the primary region uses LRS before asynchronous 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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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: Locally Redundant Storage (LRS) — Locally Redundant Storage (LRS) replicates data three times within a single physical data center in a single region. This provides protection against server rack and drive failures but does not protect against a full data center outage. It is the lowest-cost redundancy option and is suitable for scenarios where data can be reconstructed from other sources.
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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