Describe considerations for working with non-relational data on Azure →mediumMultiple ChoiceObjective-mapped
DP-900 Practice Question: Describe considerations for working with non-relational data on Azure
A global e-commerce company needs to store user session data (key-value pairs) for a web application hosted in multiple Azure regions. The data must support low-latency reads and writes (under 10 ms) and be automatically replicated across regions for high availability. The development team also requires the ability to query sessions by user ID using a simple key lookup and occasionally filter by secondary attributes such as timestamp. Which Azure data store should they choose?
⚠ Common exam trap
It's easy for candidates to confuse Azure Cache for Redis as a durable data store for session data, overlooking that it is primarily a caching layer and lacks the built-in multi-region replication and durability guarantees required for high availability in a global e-commerce scenario.
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
✓
Azure Cosmos DB
Azure Cosmos DB is correct because it provides globally distributed, multi-region writes with automatic replication, guaranteeing low-latency reads and writes under 10 ms at the 99th percentile. Its key-value API (Table API or SQL API) supports simple key lookups by user ID and secondary indexing on attributes like timestamp, meeting all stated requirements.
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
Azure Cosmos DB is purpose-built for globally distributed, horizontally scalable key-value workloads. It offers turnkey multi-region replication with multiple consistency models, automatic indexing, and single-digit-millisecond reads/writes at any scale, so user session data can be read and written from any Azure region with low latency. Its partition-key-based design maps directly to session IDs, and its SLA-backed availability and tunable consistency make it the correct durable, globally distributed store for this scenario.
- ✗
Azure Table Storage
Why it's wrong here
Azure Table Storage is a regional NoSQL key-value store, not a globally replicated service; replicating across regions requires manual configuration (e.g., Azure Storage replication options) and does not provide automatic, per-key multi-region writes or failover. It also lacks secondary indexes, so while point lookups by partition key and row key are fast, any query on a session attribute (e.g., user ID, timestamp, or status) forces a full table scan, which is inefficient at e-commerce scale. These limitations make it wrong for a globally distributed session store that needs both low-latency multi-region access and secondary query capability.
When this WOULD be correct
A company needs to store structured, non-relational data (e.g., device telemetry) with flexible schema, cost-effective storage, and simple key-based lookups, but does not require multi-region replication or sub-10 ms latency.
- ✗
Azure SQL Database
Why it's wrong here
Azure SQL Database is a relational (tabular) database with strict schema, ACID transactions, and SQL querying—features that are overkill and misaligned for simple key-value session lookups. Relational storage forces you to define a fixed schema (e.g., session ID, user ID, expiry, payload), and each lookup incurs the overhead of query planning, row parsing, and index maintenance, yielding higher latency and cost per operation compared to Cosmos DB's optimized key-value API. While SQL Database supports geo-replication, its design goal is transactional relational workloads, not low-latency, schema-flexible, globally distributed key-value access, making it wrong for this use case.
When this WOULD be correct
A question requiring a relational database with ACID transactions, complex queries (e.g., JOINs), and strong consistency for structured data like financial transactions or inventory management, where multi-region replication is not a primary requirement.
- ✗
Azure Cache for Redis
Why it's wrong here
Azure Cache for Redis is an in-memory cache, not a durable database: it is designed for ephemeral, low-latency caching and does not guarantee data persistence by default. Although Redis Enterprise (or Azure Cache tiers) can add persistence and active geo-replication, the standard service is not a globally distributed durable store—data can be lost on a node failure or reboot unless persistence is explicitly enabled, and enabling persistence introduces performance overhead. For user session data that must survive failures and be available across regions with strong consistency options, Redis fails as the primary durable store, whereas Cosmos DB provides guaranteed persistence and global distribution as a core feature.
When this WOULD be correct
A web application requires sub-millisecond read/write latency for frequently accessed session data, can tolerate data loss on failure, and does not need complex queries or automatic multi-region replication. The team plans to implement custom replication or use Redis as a cache layer in front of a persistent store.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The DP-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Azure Cosmos DBCorrect answer▾
Why this is correct
Azure Cosmos DB is purpose-built for globally distributed, horizontally scalable key-value workloads. It offers turnkey multi-region replication with multiple consistency models, automatic indexing, and single-digit-millisecond reads/writes at any scale, so user session data can be read and written from any Azure region with low latency. Its partition-key-based design maps directly to session IDs, and its SLA-backed availability and tunable consistency make it the correct durable, globally distributed store for this scenario.
✗Azure Table StorageWrong answer — click to see why▾
Why this is wrong here
Azure Table Storage does not support automatic multi-region replication for low-latency global access; it requires manual configuration or a separate multi-region setup, and its latency may exceed 10 ms for cross-region reads.
★ When this WOULD be the correct answer
A company needs to store structured, non-relational data (e.g., device telemetry) with flexible schema, cost-effective storage, and simple key-based lookups, but does not require multi-region replication or sub-10 ms latency.
Why candidates choose this
Candidates may confuse Table Storage's key-value nature and scalability with Cosmos DB's global distribution, overlooking the specific requirement for automatic multi-region replication and guaranteed low latency.
✗Azure SQL DatabaseWrong answer — click to see why▾
Why this is wrong here
Azure SQL Database is a relational database that does not natively support key-value storage with low-latency reads/writes under 10 ms across multiple regions, nor does it provide automatic multi-region replication for session data without complex configuration.
★ When this WOULD be the correct answer
A question requiring a relational database with ACID transactions, complex queries (e.g., JOINs), and strong consistency for structured data like financial transactions or inventory management, where multi-region replication is not a primary requirement.
Why candidates choose this
Candidates may associate SQL Database with high availability and global distribution features, but they overlook that it is not optimized for simple key-value lookups and sub-10 ms latency required for session state.
✗Azure Cache for RedisWrong answer — click to see why▾
Why this is wrong here
Azure Cache for Redis is an in-memory cache, not a fully managed database with automatic multi-region replication and persistent storage. It does not natively support querying by secondary attributes like timestamp without additional indexing logic.
★ When this WOULD be the correct answer
A web application requires sub-millisecond read/write latency for frequently accessed session data, can tolerate data loss on failure, and does not need complex queries or automatic multi-region replication. The team plans to implement custom replication or use Redis as a cache layer in front of a persistent store.
Why candidates choose this
Candidates associate Redis with fast key-value lookups and session storage, overlooking the question's requirements for automatic multi-region replication and secondary attribute queries, which are not native Redis features.
Analysis generated from the official DP-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Data Roles and Core Concepts
Key term
Data
Data is raw, unprocessed information, like numbers, words, or measurements, that can be stored, processed, and analyzed by computers.
Key term
Table
A table is a structured collection of data organized into rows and columns, used in databases and spreadsheets to store and manage information efficiently.
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Senior Network & Security Engineer · founder of Courseiva
This DP-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 DP-900 exam.