C100DEV Drivers, Tools, Transactions, and Search Practice Question
Exhibit
{
"name": "default",
"definition": {
"mappings": {
"dynamic": true
}
}
}Refer to the exhibit. What is the impact of setting 'dynamic' to true in this Atlas Search index definition?
⚠ Common exam trap
Candidates often underestimate the resource cost of dynamic indexing. They assume it is a 'set and forget' feature, ignoring how it bloats the search index and consumes excessive Atlas resources.
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 automatically indexes all fields in every document.
Setting 'dynamic' to true enables Atlas Search to automatically index all fields in every document within the collection. This is useful for rapid prototyping or collections with unpredictable schemas. However, it can significantly increase the size of the index and consume more resources compared to manual mappings. Understanding this balance is critical for developers managing performance and cost when dealing with large datasets and varying document structures in search-enabled collections.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
It forces all documents to follow a strict schema.
Why it's wrong here
Dynamic mapping actually removes the requirement for a strict schema, as the indexer infers types and indexes all fields automatically. This approach is the opposite of a strict schema approach, where you would explicitly define field types and exclusions for better control over the search index structure.
- ✗
It prevents the creation of any custom field mappings.
Why it's wrong here
Dynamic mapping acts as a fallback or base configuration. You can still define specific field mappings alongside a dynamic configuration. The dynamic setting simply ensures that fields not explicitly defined in the index definition are still indexed by the system using an inferred data type.
- ✓
It automatically indexes all fields in every document.
Why this is correct
When dynamic mapping is enabled, Atlas Search scans the documents and automatically indexes every field it encounters. This provides a 'search-everything' capability out of the box, which is extremely convenient for collections where you do not want to manually define mappings for every individual document field.
- ✗
It disables the indexing of nested object fields.
Why it's wrong here
Dynamic mapping includes nested object fields by default. It traverses the document structure, including embedded objects and arrays, and indexes them accordingly. If you wanted to exclude specific fields or handle nested structures differently, you would need to use static or custom mapping definitions instead.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official MongoDB exam blueprint
This C100DEV practice question is part of Courseiva's free MongoDB 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 C100DEV exam.