AZ-305 Design data storage solutions Practice Question
This AZ-305 practice question tests your understanding of design data storage solutions. 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.
A global e-commerce company needs a database solution that can handle high-velocity writes from user transactions across multiple regions. They require multi-region writes with automatic conflict resolution and single-digit millisecond latency for reads and writes. Which Azure data store should they use?
Cosmos DB provides global distribution with multi-master support, automatic conflict resolution, and single-digit millisecond latency.
B
Azure Table Storage
Why wrong: Table Storage supports geo-replication but does not offer multi-region writes with automatic conflict resolution; it uses a single primary region for writes.
C
Azure SQL Database
Why wrong: Azure SQL Database supports active geo-replication for read-scale but not multi-region writes; failover groups require a single write region.
D
Azure Redis Cache
Why wrong: Redis Cache is an in-memory cache, not a durable, globally write-capable database for transaction persistence.
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 offers multi-region writes with automatic conflict resolution using last-writer-wins (LWW) or custom conflict resolution policies, and it guarantees single-digit millisecond latency for both reads and writes at the 99th percentile. Its globally distributed, multi-model design is purpose-built for high-velocity transactional workloads that require active-active replication across regions.
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 provides global distribution with multi-master support, automatic conflict resolution, and single-digit millisecond latency.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Table Storage
Why it's wrong here
Table Storage supports geo-replication but does not offer multi-region writes with automatic conflict resolution; it uses a single primary region for writes.
✗
Azure SQL Database
Why it's wrong here
Azure SQL Database supports active geo-replication for read-scale but not multi-region writes; failover groups require a single write region.
✗
Azure Redis Cache
Why it's wrong here
Redis Cache is an in-memory cache, not a durable, globally write-capable database for transaction persistence.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Azure SQL Database's active geo-replication (which supports only read-scale secondaries) with true multi-region writes, or they assume Azure Table Storage's global replication is equivalent to Cosmos DB's active-active capability.
Detailed technical explanation
How to think about this question
Azure Cosmos DB achieves single-digit millisecond latency through its multi-homing API and automatic indexing of all data, combined with a wire protocol that supports direct connectivity to the nearest regional endpoint. Under the hood, conflict resolution can be configured with custom stored procedures or LWW, and the system uses a quorum-based replication model with tunable consistency levels (from eventual to strong) to balance performance and correctness. In a real-world scenario, a global e-commerce platform would use Cosmos DB's multi-region writes to handle Black Friday traffic spikes across continents without downtime.
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 offers multi-region writes with automatic conflict resolution using last-writer-wins (LWW) or custom conflict resolution policies, and it guarantees single-digit millisecond latency for both reads and writes at the 99th percentile. Its globally distributed, multi-model design is purpose-built for high-velocity transactional workloads that require active-active replication across regions.
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.
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Question Discussion
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