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 the context of MongoDB development, you are creating a new service that is expected to handle high load. You've decided to leverage the MongoDB drivers' connection pooling capability. What best describes connection pooling and its advantages?

A : Connection pooling ensures secure data transfer between the client and the server by encrypting all connections in the pool.

B : Connection pooling allows a client to connect to a database only when a data transfer operation occurs, reducing the memory requirements.

C : Connection pooling involves maintaining a "pool" of open database connections, which can be reused for multiple requests, improving performance.

D : Connection pooling refers to the storage of multiple connection strings for redundancy, increasing system reliability.

Answer: C

Question 2

What is the best practice in using the $match operator?

A : It doesn't matter when we apply $match stage.

B : MongoDB does not have a $match stage.

C : The later in the pipeline, the better.

D : The earlier in the pipeline, the better. Not only because we will be using expression filters which reduce the number of documents to be processed, but also because we can use indexes.

Answer: D

Question 3

Suppose you have a restaurants collection with the following document structure:

{

_id: ObjectId("5eb3d668b31de5d588f42931"),

address: {

building: '6409',

coord: [ -74.00528899999999, 40.628886 ],

street: '11 Avenue',

zipcode: '11219'

borough: 'Brooklyn',

cuisine: 'American',

grades: [

{

date: ISODate("2014-07-18T00:00:00.000Z"),

grade: 'A',

score: 12

{

date: ISODate("2013-07-30T00:00:00.000Z"),

grade: 'A',

score: 12

{

date: ISODate("2013-02-13T00:00:00.000Z"),

grade: 'A',

score: 11

{ date: ISODate("2012-08-16T00:00:00.000Z"),

grade: 'A',

score: 2 },

{

date: ISODate("2011-08-17T00:00:00.000Z"),

grade: 'A',

score: 11

}

name: 'Regina Caterers',

restaurant_id: '40356649'

}

You don't have any indexes so far. What will the query plan look like for the following query?

db.restaurants.find( { "cuisine": "American" } )

A : IXSCAN

B : SORT

C : FETCH

D : COLLSCAN

Answer: D

Question 4

Where is the MongoDB configuration file usually located?

A :

B :

C :

D :

E :

Answer: B

Question 5

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

{

name: 'Wize',

relationships: [

{

is_past: false,

title: 'Head of Product',

person: {

first_name: 'Ethan',

last_name: 'Smith',

permalink: 'ethan-smith'

}

{

is_past: true,

title: 'Director, Business Development',

person: {

first_name: 'Stephanie',

last_name: 'Quay',

permalink: 'stephanie-quay'

}

{

is_past: true,

title: 'Sr. Engineer',

person: {

first_name: 'Stefan',

last_name: 'Antonowicz',

permalink: 'stefan-antonowicz'

}

]

}

Which of the following queries should you use to extract all companies that have "Co-Founder" title in relationships field (Array)?

A : db.companies.find( { relationships: { $expr: { title: 'Co-Founder' } } } )

B : db.companies.find( { relationships: { $elemMatch: { title: 'Co-Founder' } } } )

C : db.companies.find( { relationships: { $match: { title: 'Co-Founder' } } } )

D : db.companies.find( { relationships: { $eq: { title: 'Co-Founder' } } } )

Answer: B

Page: 1 / 83

Total 411 Questions | Updated On: Mar 08, 2026

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