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Stay Ahead with Latest C100DEV MongoDB Certified Developer Associate Practice Test Questions 2026

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Total 411 Questions | Updated On: Sep 22, 2026

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Question 1

Suppose you have a companies collection in your database. Only the following documents are stored in this collection:

{

_id: ObjectId("52cdef7c4bab8bd675297da4"),

category_code: 'search',

founded_year: 2006

{

_id: ObjectId("52cdef7c4bab8bd675297da5"),

category_code: 'advertising',

founded_year: 2002

{

_id: ObjectId("52cdef7c4bab8bd675297da7"),

category_code: 'advertising',

founded_year: 2004

{

_id: ObjectId("52cdef7c4bab8bd675297da8"),

category_code: 'advertising',

founded_year: 2008

{

_id: ObjectId("52cdef7c4bab8bd675297daa"),

category_code: 'games_video',

founded_year: 2007

{

_id: ObjectId("52cdef7c4bab8bd675297dac"),

category_code: 'games_video',

founded_year: 2004

{

_id: ObjectId("52cdef7c4bab8bd675297dae"),

category_code: 'web',

founded_year: 2006

}

What is the default sort order in the result set returned in response to the following query?

db.companies.aggregate( [ { "$sortByCount": "$category_code" } ] )

A : ascending

B : descending

Answer: B

Question 2

Select true statements about capped collections. (select 2)

A : Capped collections are fixed-size collections.

B : If the collection is full, the oldest document in the collection is removed when a new document is added to the collection.

C : Capped collections don't guarantee preservation of the insertion order.

D : Capped collections automatically remove the most recent documents in the collection to make room for new documents.

Answer: A,B

Question 3

Data modeling. You are considering the use of nesting or references in your data model. Documents can grow rapidly. Which option would be more appropriate?

A : Use of reference.

B : Use of nesting.

Answer: A

Question 4

A collection called players contains the following documents:

[

{ _id: 1, user: 'Tom', scores: [ 23, 56, 3, 52, 62 ], bonus: 5 },

{ _id: 2, user: 'Jane', scores: [ 42, 50, 10 ], bonus: 3 }

]

You want to add additional fields to each document:

-> total_score (sum of the scores Array)

-> avg_score (average score in scores Array)

-> total_score_with_bonus (total_score + bonus)

Expected output:

[

{

_id: 1,

user: 'Tom',

scores: [ 23, 56, 3, 52, 62 ],

bonus: 5,

total_score: 196,

avg_score: 39.2,

total_score_with_bonus: 201

{

_id: 2,

user: 'Jane',

scores: [ 42, 50, 10 ],

bonus: 3,

total_score: 102,

avg_score: 34,

total_score_with_bonus: 105

}

]

Which query do you need to use?

A : db.players.aggregate([{ $addFields: { total_score: { $sum: '$scores' }, avg_score: { $avg: '$scores' } }}, { $addFields: { total_score_with_bonus: { $add: ['$total_score', '$bonus'] } }}])

B : db.players.aggregate([{ $addFields: { total_score: { $sum: '$scores' }, avg_score: { $avg: '$scores' }, total_score_with_bonus: { $add: ['$total_score', '$bonus'] } }}])

C : db.players.aggregate([{ $add: { total_score: { $sum: '$scores' }, avg_score: { $avg: '$scores' } }}, { $add: { total_score_with_bonus: { $add: ['$total_score', '$bonus'] } }}])

Answer: A

Question 5

Use case: e-learning platform

Which of the following scenarios is the best candidate to use the Extended Reference Pattern to avoid additional reads by joins/lookups?

A : Our app needs to retrieve a course and information about its instructor.

B : A course model needs to store references to image of the course that are kept in an external location outside the database.

C : Our app needs to retrieve a course and its ten most recent reviews.

D : A course model needs to store a counter representing the number of times it was purchased.

Answer: A

Page: 1 / 83

Total 411 Questions | Updated On: Sep 22, 2026

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