Azure Cosmos DB is the correct choice because it is a fully managed NoSQL database designed for globally distributed, JSON document-oriented applications that demand single-digit millisecond latency for reads and writes at any scale, and it natively supports multi-region writes with automatic failover through its multi-master replication. This capability is rooted in Cosmos DB’s turnkey global distribution model, which allows you to configure multiple write regions, ensuring high availability and low latency worldwide regardless of geographic load. On the Microsoft Azure Solutions Architect Expert AZ-305 exam, this scenario tests your understanding of selecting the appropriate data store for global, latency-sensitive workloads, often appearing as a trap where candidates might mistakenly choose Azure SQL Database or Azure Table Storage—both lack native multi-region write support and automatic failover for NoSQL JSON data. A key memory tip is to associate “global, low-latency, multi-write” directly with Cosmos DB’s multi-master feature, and remember that if the requirement specifies JSON documents, Cosmos DB’s SQL API is the natural fit.
AZ-305 Design data storage solutions Practice Question
This AZ-305 practice question tests your understanding of design data storage solutions. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 needs a fully managed NoSQL database for a JSON document-oriented application that requires low latency (single-digit milliseconds) for reads and writes at any scale. The application will run globally and needs multi-region writes with automatic failover. Which Azure data store should they use?
Cosmos DB offers multi-region writes, elastic scalability, and guarantees single-digit millisecond latency at the 99th percentile. It supports document models natively.
B
Azure Table Storage
Why wrong: Azure Table Storage is a NoSQL key-value store but does not support multi-region writes or automatic failover. Latency is higher and scaling is more manual.
C
Azure SQL Database
Why wrong: Azure SQL Database is a relational database engine, not a NoSQL document store. It does not natively store JSON documents as primary data.
D
Azure Cache for Redis
Why wrong: Azure Cache for Redis is an in-memory data store primarily used for caching and session state. It is not a durable NoSQL database for global writes with automatic failover.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Cosmos DB
Azure Cosmos DB is the correct choice because it is a fully managed NoSQL database that natively supports JSON documents, offers single-digit millisecond latency for reads and writes at any scale, and provides multi-region writes with automatic failover through its multi-master replication capability. Its global distribution model allows you to configure multiple write regions, ensuring high availability and low latency worldwide.
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.
✓
Azure Cosmos DB
Why this is correct
Cosmos DB offers multi-region writes, elastic scalability, and guarantees single-digit millisecond latency at the 99th percentile. It supports document models natively.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Table Storage
Why it's wrong here
Azure Table Storage is a NoSQL key-value store but does not support multi-region writes or automatic failover. Latency is higher and scaling is more manual.
✗
Azure SQL Database
Why it's wrong here
Azure SQL Database is a relational database engine, not a NoSQL document store. It does not natively store JSON documents as primary data.
✗
Azure Cache for Redis
Why it's wrong here
Azure Cache for Redis is an in-memory data store primarily used for caching and session state. It is not a durable NoSQL database for global writes with automatic failover.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Azure Table Storage (a simple key-value store) with a fully managed NoSQL database, overlooking that it lacks native JSON support, multi-region writes, and automatic failover capabilities required for global, low-latency applications.
Detailed technical explanation
How to think about this question
Azure Cosmos DB achieves single-digit millisecond latency by using a multi-master replication protocol and indexing all data automatically. Its consistency levels (e.g., bounded staleness, session, consistent prefix) allow you to trade off between performance and consistency, which is critical for globally distributed applications. In a real-world scenario, a global e-commerce platform would use Cosmos DB to handle shopping cart data with multi-region writes, ensuring that users in different continents experience low latency and seamless failover during regional outages.
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-305 question in full detail.
Design data storage solutions — This question tests Design data storage solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Azure Cosmos DB — Azure Cosmos DB is the correct choice because it is a fully managed NoSQL database that natively supports JSON documents, offers single-digit millisecond latency for reads and writes at any scale, and provides multi-region writes with automatic failover through its multi-master replication capability. Its global distribution model allows you to configure multiple write regions, ensuring high availability and low latency worldwide.
What should I do if I get this AZ-305 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.
About these practice questions
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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 gaming company is developing a multiplayer online game that requires a low-latency data store for player profiles, inventory, and session state. The data is accessed globally, and the solution must support millions of concurrent players. The company expects write-heavy workloads with occasional reads. The solution must provide single-digit millisecond latency for reads and writes. The company also needs to run analytics on the data to understand player behavior, but analytics queries can tolerate higher latency (minutes). Which Azure data storage solution should the company recommend for the transactional data?
medium
A.Azure SQL Database with active geo-replication
B.Azure Redis Cache with persistence
✓ C.Azure Cosmos DB with multiple write regions
D.Azure Table Storage with geo-redundancy
Why C: Option B is correct because Azure Cosmos DB with multi-master writes provides global low-latency access and high throughput. Option A is wrong because Azure SQL Database with geo-replication may have higher latency for writes due to replication. Option C is wrong because Azure Redis Cache is a caching layer, not a durable data store. Option D is wrong because Azure Table Storage is not designed for single-digit millisecond latency and global distribution.
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This AZ-305 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-305 exam.
Question Discussion
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