- A
Locally-redundant storage (LRS)
Why wrong: LRS replicates data three times within a single physical datacenter in the primary region. If the entire datacenter fails, the data is lost. LRS does not meet the requirement to survive a datacenter failure.
- B
Zone-redundant storage (ZRS)
ZRS replicates data synchronously across three Azure availability zones within the primary region. Each zone is a physically separate datacenter (or multiple datacenters) with independent power and networking. This protects against the failure of a single datacenter. ZRS is more expensive than LRS but less expensive than geo-redundant options, making it the most cost-effective choice for this requirement.
- C
Geo-redundant storage (GRS)
Why wrong: GRS replicates data to a secondary region that is hundreds of kilometers apart. While this provides region-level disaster recovery, it is more expensive than ZRS. The company only needs protection within the primary region, so GRS is unnecessarily costly and does not offer a cost advantage.
- D
Read-access geo-redundant storage (RA-GRS)
Why wrong: RA-GRS includes all the features of GRS plus read access to the secondary region. This is even more expensive than GRS and provides functionality (reading from secondary) that the company explicitly does not require. It is not the most cost-effective option for the stated need.
Quick Answer
The correct choice is Zone-redundant storage (ZRS). ZRS replicates your data synchronously across three separate Azure availability zones within a single region, so if an entire datacenter—which corresponds to one zone—fails, your compliance logs remain available without interruption. This meets the requirement for protection against a datacenter failure within the primary region while keeping costs lower than geo-redundant options, since you are not paying for cross-region replication. On the AZ-900 exam, this scenario tests your understanding of how ZRS balances high availability and cost; a common trap is choosing Geo-redundant storage (GRS) because it also offers durability, but GRS is more expensive and provides secondary region access that the company explicitly does not need. Remember the memory tip: “ZRS = Zone Redundancy, Same Region” — if you only need to survive a datacenter failure locally and want to save money, ZRS is your zone-based shield.
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 stores compliance logs in Azure Blob Storage. The logs must remain available even if an entire Azure datacenter within the primary region fails. The company is cost-conscious and wants to minimize storage costs while meeting this availability requirement. The company does not need to access the data from a secondary location during a disaster. Which storage replication option should the company choose?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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) replicates data synchronously across three Azure availability zones within the primary region. This ensures data remains available even if an entire datacenter (one zone) fails, while avoiding the higher cost and cross-region replication of GRS. Since the company does not need secondary region access and wants to minimize costs, ZRS meets the requirement without paying for geo-redundancy.
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 datacenter in the primary region. If the entire datacenter fails, the data is lost. LRS does not meet the requirement to survive a datacenter failure.
- ✓
Zone-redundant storage (ZRS)
Why this is correct
ZRS replicates data synchronously across three Azure availability zones within the primary region. Each zone is a physically separate datacenter (or multiple datacenters) with independent power and networking. This protects against the failure of a single datacenter. ZRS is more expensive than LRS but less expensive than geo-redundant options, making it the most cost-effective choice for this requirement.
Clue confirmation
The clue words "primary", "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Geo-redundant storage (GRS)
Why it's wrong here
GRS replicates data to a secondary region that is hundreds of kilometers apart. While this provides region-level disaster recovery, it is more expensive than ZRS. The company only needs protection within the primary region, so GRS is unnecessarily costly and does not offer a cost advantage.
- ✗
Read-access geo-redundant storage (RA-GRS)
Why it's wrong here
RA-GRS includes all the features of GRS plus read access to the secondary region. This is even more expensive than GRS and provides functionality (reading from secondary) that the company explicitly does not require. It is not the most cost-effective option for the stated need.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose LRS thinking it is cheapest, but they overlook that LRS cannot survive a full datacenter failure, while ZRS provides the required availability at minimal additional cost.
Detailed technical explanation
How to think about this question
ZRS uses synchronous replication across three Azure availability zones, each with independent power, cooling, and networking, providing a Recovery Point Objective (RPO) of zero and a Recovery Time Objective (RTO) typically within minutes. Unlike GRS, ZRS does not require a secondary region, so there is no cross-region bandwidth cost or additional latency for write operations. In a real-world scenario, if a zone fails, Azure automatically fails over to another zone without manual intervention, and the storage account endpoint remains unchanged.
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.
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) replicates data synchronously across three Azure availability zones within the primary region. This ensures data remains available even if an entire datacenter (one zone) fails, while avoiding the higher cost and cross-region replication of GRS. Since the company does not need secondary region access and wants to minimize costs, ZRS meets the requirement without paying for geo-redundancy.
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.
Are there clue words in this question I should notice?
Yes — watch for: "primary", "minimum / minimize". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
2 more ways this is tested on AZ-900
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company stores a critical database in Azure Blob Storage. The data must remain available even if an entire Azure datacenter fails. The company uses the East US region, which supports availability zones. They want the lowest-cost storage redundancy option that protects against a full datacenter failure while keeping all data within the East US region. Which redundancy option should they choose?
medium- A.Locally redundant storage (LRS)
- ✓ B.Zone-redundant storage (ZRS)
- C.Geo-redundant storage (GRS)
- D.Read-access geo-redundant storage (RA-GRS)
Why B: Zone-redundant storage (ZRS) is the correct choice because it synchronously replicates data across three availability zones within the East US region, ensuring data remains accessible even if an entire datacenter (one zone) fails. This meets the requirement for intra-region protection against a full datacenter failure at the lowest cost, as ZRS does not incur the additional expense of geo-replication.
Variation 2. A healthcare organization stores patient records in Azure Blob Storage. They require that data remains available even if an entire Azure datacenter fails, and they also need to ensure data is replicated within the same region for low latency. Which storage redundancy option should they choose?
hard- A.Locally Redundant Storage (LRS)
- ✓ B.Zone-Redundant Storage (ZRS)
- C.Geo-Redundant Storage (GRS)
- D.Read-Access Geo-Redundant Storage (RA-GRS)
Why B: Zone-Redundant Storage (ZRS) synchronously replicates data across three Azure availability zones within the same region, ensuring data remains available even if an entire datacenter (one zone) fails. This meets both the availability requirement and the low-latency requirement because replication stays within the region, avoiding cross-region latency.
Last reviewed: Jun 11, 2026
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.
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