DA0-002 Data Concepts and Environments Practice Question
A company needs to store user session data for a web application. Each session has a unique session ID, and the data must be retrieved very quickly by session ID. The data does not require complex relationships or transactions. Which type of NoSQL database is most appropriate?
⚠ Common exam trap
Many candidates choose a document store like MongoDB because they associate 'session data' with JSON objects, overlooking that key-value stores are purpose-built for the exact use case of fast, simple key-based retrieval without the overhead of document querying.
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
✓
Key-value store (e.g., Redis)
A key-value store like Redis is the most appropriate choice because it is optimized for extremely fast lookups by a unique key (session ID) and does not require complex relationships or transactions. Redis stores data in memory, providing sub-millisecond retrieval times ideal for session management, and supports built-in expiration (TTL) to automatically clean up stale sessions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Key-value store (e.g., Redis)
Why this is correct
Key-value stores provide high-performance lookups by key.
- ✗
Wide-column store (e.g., Cassandra)
Why it's wrong here
Wide-column stores are for large-scale analytics, not simple key lookups.
- ✗
Document store (e.g., MongoDB)
Why it's wrong here
A document store like MongoDB organises data in flexible, schema-less JSON-like documents, which is unnecessary here because the requirement is simply to retrieve a blob of session data by a unique key, not to query nested fields or run aggregations. This option is tempting because document stores are often used for session storage in practice, but the correct choice is a key-value store, which directly maps session IDs to values with lower overhead and faster lookups. A document store would be appropriate if the session data required complex queries on subfields or needed to be indexed by multiple attributes.
- ✗
Graph database (e.g., Neo4j)
Why it's wrong here
Graph databases are for relationships, not session storage.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DA0-002 practice question is part of Courseiva's free CompTIA 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 DA0-002 exam.