Free MongoDB C100DEV Exam Questions

Become MongoDB Certified with updated C100DEV exam questions and correct answers

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Total 411 Questions | Updated On: Mar 08, 2026

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Question 1

In MongoDB, which statement accurately describes a typical task for a MongoDB developer related to schema validation?

A : Schema validation enables the creation of complex relationships between multiple collections.

B : Schema validation guarantees the uniqueness of a specific field across all documents in a collection.

C : Schema validation ensures the presence of required fields and their data types within a document.

D : Schema validation provides real-time data synchronization across multiple MongoDB instances.

Answer: C

Question 2

Which of the following constraints might impact your data model for MongoDB? (Select three)

A : Operating System

B : RAM

C : Network

D : File System Type

E : Security & Compliance

Answer: B,C,E

Question 3

Consider a MongoDB collection named products which has documents in the following format:

{

"_id" : ObjectId("5f5b0d2f3e3dfbcc11c84444"),

"name" : "Smartphone",

"brand" : "Apple",

"category" : "Electronics",

"price" : 1000,

"discount" : 0.1

}

What is the correct syntax to update the "price" field of all documents in the products collection by multiplying it with (1 - discount) using the $set operator and the $multiply operator?

A : db.products.update( {}, { $set: { price: { $multiply: ["$price", { $subtract: [1, "$discount"] }] } } })

B : db.products.updateMany( {}, { $set: { price: { $multiply: ["$price", 1 - $discount] } } })

C : db.products.update( {}, { $set: { price: { $multiply: ["$price", 1 - $discount] } } })

D : db.products.updateMany( {}, { $set: { price: { $multiply: ["$price", { $subtract: [1, "$discount"] }] } } })

Answer: D

Question 4

As a MongoDB Developer, you are tasked with optimizing a MongoDB database. Your collection has documents with the following structure:

{

"_id": ObjectId(),

"user_id": Number,

"user_data": {

"name": String,

"email": String,

"phone": String,

"address": {

"city": String,

"state": String,

"country": String

}

"transactions": [

{

"transaction_id": Number,

"amount": Number,

"date": Date

}

]

}

The application frequently queries for the total transaction amount for users based on the city. Which index should you create to optimize the performance of these queries?

A : db.collection.createIndex({"user_data.address.city": 1})

B : db.collection.createIndex({"user_data.address.city": 1, "transactions.amount": 1})

C : db.collection.createIndex({"user_id": 1})

D : db.collection.createIndex({"transactions.amount": 1})

E : db.collection.createIndex({"transactions": 1})

Answer: B

Question 5

In your database there is a collection named trips with the following document structure:

{

'_id': ObjectId("572bb8222b288919b68abf6d"),

'trip_duration': 858,

'start_station id': 532,

'end_station_id': 401,

'bike_id': 17057,

'start_station_loc': { type: 'Point', coordinates: [ -73.960876, 40.710451 ] },

'end_station_loc': { type: 'Point', coordinates: [ -73.98997825, 40.72019576 ] },

'start_time': ISODate("2016-01-01T00:09:31.000Z"),

'stop_time': ISODate("2016-01-01T00:23:49.000Z")

}

How can you extract all trips from this collection ended at stations that are to the west of the -73.5 longitude coordinate?

A : db.trips.find( { 'end_station_loc.coordinates.0': { $gt: -73.5 } } )

B : db.trips.find( { 'coordinates': { $lt: -73.5 } } )

C : db.trips.find( { 'end_station_loc.coordinates.0': { $lt: -73.5 } } )

D : db.trips.find( { 'end_station_loc.coordinates.1': { $lt: -73.5 } } )

Answer: C

Page: 1 / 83

Total 411 Questions | Updated On: Mar 08, 2026

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