DP-900 Practice Question: Describe considerations for working with non-relational data on Azure
Which TWO of the following are true about Azure Cosmos DB?
⚠ Common exam trap
DP-900 often tests the confusion between Cosmos DB and Azure SQL Database — candidates may incorrectly associate DTUs with Cosmos DB or assume the default consistency is Strong, when it is actually Session.
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
✓
It guarantees single-digit millisecond latency for reads and writes at the 99th percentile.
Option C is correct because Azure Cosmos DB is designed and SLA-backed to deliver single-digit millisecond latency for reads and writes at the 99th percentile, which is one of its core differentiators as a globally distributed database. Option E is correct because Cosmos DB is a multi-model database that natively supports document (SQL/Core API), key-value (Table API), graph (Gremlin API), and column-family (Cassandra API) data models. Option A is incorrect because the default consistency level in Cosmos DB is Session, not Strong; Strong is the strongest of the five levels but is not the default. Option B is incorrect because Cosmos DB measures throughput in Request Units per second (RU/s), whereas DTUs are the performance unit used by Azure SQL Database. Option D is incorrect because Cosmos DB is a NoSQL, multi-model database service, not a relational database management system.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The default consistency level is Strong.
Why it's wrong here
Azure Cosmos DB offers multiple consistency levels, including Strong, Bounded Staleness, Session, Consistent Prefix, and Eventual, but the default is Session, not Strong. Session consistency guarantees monotonic reads and writes for a single client session, providing a practical balance between performance and data consistency. Strong consistency is available but comes with higher read latency and is not supported with multi-region write configurations, making it unsuitable as the default for most workloads.
- ✗
It uses DTUs to measure performance.
Why it's wrong here
Azure Cosmos DB measures performance using Request Units (RUs) per second, not DTUs. DTUs (Database Transaction Units) are a partially abstracted metric used by Azure SQL Database to represent a blended mix of CPU, memory, and I/O capacity. In Cosmos DB, each operation's resource consumption depends on factors like item size, indexing, consistency level, and query complexity, so RU provisioning accurately reflects the cost of each request and enables fine-grained scaling.
- ✓
It guarantees single-digit millisecond latency for reads and writes at the 99th percentile.
Why this is correct
Azure Cosmos DB's globally distributed, multi-master architecture and automatic indexing capabilities are fundamental to its ability to guarantee single-digit millisecond latency for reads and writes at the 99th percentile. This performance commitment is enshrined in its financially-backed Service Level Agreement (SLA), ensuring predictable and consistent high-speed data access. This accurately describes a core truth about Azure Cosmos DB, directly satisfying the question's requirement to identify a true characteristic.
- ✗
It is a relational database management system.
Why it's wrong here
Cosmos DB is a NoSQL database that uses a schema-agnostic, multi-model approach with APIs for document, graph, and key-value data, whereas a relational database management system enforces a fixed schema with ACID transactions and SQL-based joins. It is tempting because Cosmos DB offers a SQL API that mimics relational query syntax, but it still lacks relational integrity constraints and normalised table structures, making it the correct choice only for globally distributed, low-latency workloads that do not require strict relational modelling.
- ✓
It supports multiple data models including document, key-value, graph, and column-family.
Why this is correct
Azure Cosmos DB is a multi-model NoSQL database that natively supports document, key-value, graph, and column-family data models through its diverse APIs. You can interact with the same underlying storage using the SQL API for documents, the Cassandra API for wide-column data, the Gremlin API for graphs, and the Table API for key-value stores. This breadth allows you to employ a single globally distributed service across heterogeneous application patterns without needing separate database engines.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
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