DP-900 Describe core data concepts Practice Question
This DP-900 practice question tests your understanding of describe core data concepts. 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 THREE factors should you consider when choosing between Azure SQL Database and Azure Cosmos DB for a new application?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Need for multi-region writes
Option A is correct because Azure Cosmos DB supports multi-region writes with its multi-master replication, enabling low-latency writes across multiple geographic regions, which is a key differentiator from Azure SQL Database that only supports a single write region. This is critical for globally distributed applications requiring high availability and local write performance.
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.
✓
Need for multi-region writes
Why this is correct
Cosmos DB supports multi-master replication; SQL Database requires failover groups for multi-region.
Related concept
Read the scenario before looking for a memorised answer.
✓
Schema flexibility requirements
Why this is correct
Cosmos DB is schema-agnostic, while SQL Database requires a fixed schema.
Related concept
Read the scenario before looking for a memorised answer.
Read the scenario before looking for a memorised answer.
✗
Support for JSON data
Why it's wrong here
Both support JSON; SQL Database has JSON functions, Cosmos DB natively stores JSON.
✗
Support for T-SQL queries
Why it's wrong here
Both support SQL-like queries; Cosmos DB SQL API is similar to T-SQL.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may assume JSON support or T-SQL compatibility are deciding factors, but both databases handle JSON (though differently) and T-SQL is exclusive to SQL Database, so the real differentiators are multi-region writes, schema flexibility, and transaction consistency guarantees (e.g., ACID in SQL Database vs. tunable consistency levels in Cosmos DB).
Trap categories for this question
Similar concept trap
Both support SQL-like queries; Cosmos DB SQL API is similar to T-SQL.
Detailed technical explanation
How to think about this question
Azure Cosmos DB's multi-region writes are enabled by its multi-master replication protocol, which uses a conflict resolution mechanism (e.g., last-writer-wins or custom) to handle concurrent updates, ensuring eventual consistency across regions. In contrast, Azure SQL Database relies on active geo-replication with a single primary for writes, requiring failover for write region changes. Schema flexibility in Cosmos DB is inherent due to its document model, while Azure SQL Database requires predefined schemas with ALTER TABLE operations for changes, impacting development agility.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-900 question in full detail.
Describe core data concepts — This question tests Describe core data concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Need for multi-region writes — Option A is correct because Azure Cosmos DB supports multi-region writes with its multi-master replication, enabling low-latency writes across multiple geographic regions, which is a key differentiator from Azure SQL Database that only supports a single write region. This is critical for globally distributed applications requiring high availability and local write performance.
What should I do if I get this DP-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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