Quick Answer
The answer is graph, document, and key-value. These three are core NoSQL database types, each designed for specific data models that differ from traditional relational tables. Document databases like MongoDB store data in flexible, JSON-like structures, allowing nested fields and schema-less designs, while key-value stores such as Redis use a simple associative array for fast lookups, and graph databases like Neo4j excel at managing interconnected entities and relationships. On the CompTIA Data+ DA0-001 exam, this question tests your ability to distinguish NoSQL categories from SQL or from hybrid systems like NewSQL; a common trap is confusing wide-column stores (e.g., Cassandra) with key-value or document types. To remember the three core types, think of the mnemonic “DKG” for Document, Key-value, Graph—each handles data differently, but all reject rigid table schemas.
This DA0-001 practice question tests your understanding of comparing and contrasting data concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 of the following are NoSQL database types?
Document
Document stores (e.g., MongoDB) are NoSQL.
Hierarchical
Why wrong: Hierarchical databases are an older model, not typically considered NoSQL.
Relational
Why wrong: Relational databases (SQL) are not NoSQL.
Key-Value
Key-value stores (e.g., Redis) are NoSQL.
Graph
Graph databases are a NoSQL category.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Document
Option A is correct because document databases, such as MongoDB, store data in flexible, JSON-like documents (BSON in MongoDB's case). This allows for nested structures and schema-less designs, making them a core NoSQL category distinct from relational models.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Document
Why this is correct
Document stores (e.g., MongoDB) are NoSQL.
Related concept
Read the scenario before looking for a memorised answer.
Hierarchical
Why it's wrong here
Hierarchical databases are an older model, not typically considered NoSQL.
Relational
Why it's wrong here
Relational databases (SQL) are not NoSQL.
Key-Value
Why this is correct
Key-value stores (e.g., Redis) are NoSQL.
Related concept
Read the scenario before looking for a memorised answer.
Graph
Why this is correct
Graph databases are a NoSQL category.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
CompTIA often tests the distinction between legacy database models (hierarchical) and modern NoSQL categories, leading candidates to mistakenly include hierarchical as a NoSQL type due to its non-relational nature.
Detailed technical explanation
NoSQL databases are broadly categorized into document, key-value, column-family, and graph types. Key-value stores (e.g., Redis) use a simple hash map for ultra-fast lookups, while graph databases (e.g., Neo4j) leverage nodes and edges with traversal algorithms like BFS for relationship-heavy queries. Document stores internally use B-tree or LSM-tree indexes on fields, enabling rich queries beyond simple key lookups.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the DA0-001 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Comparing and Contrasting Data Concepts — This question tests Comparing and Contrasting Data Concepts — Read the scenario before looking for a memorised answer..
The correct answer is: Document — Option A is correct because document databases, such as MongoDB, store data in flexible, JSON-like documents (BSON in MongoDB's case). This allows for nested structures and schema-less designs, making them a core NoSQL category distinct from relational models.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This DA0-001 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 DA0-001 exam.
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