DA0-002 Data Concepts and Environments Practice Question
Which database index type is most commonly used for exact-match lookups and range queries in a B-tree structure?
⚠ Common exam trap
Candidates often confuse 'clustered index' as a separate index type, but it is actually a physical implementation of a B-tree where the leaf nodes contain the full row data, not a different algorithmic structure.
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
✓
B-tree index
A B-tree index is the correct answer because it maintains sorted data in a balanced tree structure, enabling both exact-match lookups (via equality searches) and efficient range queries (via ordered traversal of leaf nodes). This dual capability makes it the standard index type in relational databases like MySQL, PostgreSQL, and Oracle for general-purpose querying.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
B-tree index
Why this is correct
A B-tree index stores keys in sorted order across balanced nodes, so exact-match lookups traverse a single root-to-leaf path in logarithmic time, while range queries exploit the sorted leaf chain to scan contiguous values. This satisfies both the equality and range requirements stated in the stem.
- ✗
Hash index
Why it's wrong here
Hash indexes map keys to buckets through a hash function, so they support equality predicates only and cannot satisfy range queries since bucket order bears no relation to key order. Tempting for fast exact-match lookups, but the stem also demands range scans, which B-tree indexes provide.
- ✗
Clustered index
Why it's wrong here
A clustered index defines the physical row order of the table itself, so only one can exist per table and it governs storage rather than providing the separate lookup structure the stem describes. It is tempting because clustered indexes do support exact-match and range seeks; they are chosen when physical ordering on that key benefits the workload.
- ✗
Bitmap index
Why it's wrong here
Bitmap indexes store one bit per distinct value per row, suiting low-cardinality columns in analytical warehouses, not ordered traversal. They cannot serve range predicates efficiently because bitmaps carry no key ordering; B-tree indexes maintain sorted keys, which is what exact-match and range scans require.
Visual reference
Go deeper
Related to this question
About these practice questions
Courseiva writes every DA0-002 question from scratch — 1,004 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
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.