100% Free MongoDB C100DEV Practice Exam Questions Online 2026

Question 1

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

Question 2

Consider a collection named orders with the following documents:{ "_id" : ObjectId("5f0a7e80d8c9c7b5a48c49e1"), "order_id" : 101, "customer_name" : "John Doe", "order_date" : ISODate("2022-01-01T00:00:00.000Z"), "items" : [ { "product_name" : "Apple", "quantity" : 2, "price" : 0.99 }, { "product_name" : "Banana", "quantity" : 5, "price" : 0.5 } ]} { "_id" : ObjectId("5f0a7e80d8c9c7b5a48c49e2"), "order_id" : 102, "customer_name" : "Jane Doe", "order_date" : ISODate("2022-01-02T00:00:00.000Z"), "items" : [ { "product_name" : "Orange", "quantity" : 3, "price" : 0.79 }, { "product_name" : "Mango", "quantity" : 2, "price" : 1.99 } ]} { "_id" : ObjectId("5f0a7e80d8c9c7b5a48c49e3"), "order_id" : 103, "customer_name" : "Bob Smith", "order_date" : ISODate("2022-01-03T00:00:00.000Z"), "items" : [ { "product_name" : "Peach", "quantity" : 4, "price" : 1.49 }, { "product_name" : "Pear", "quantity" : 1, "price" : 2.99 } ]}What is the query to retrieve the total sales for each customer in the orders collection?

A : db.orders.aggregate([ { $group: { _id: "$customer_name", total_sales: { $sum: { $multiply: ["$items.quantity", "$items.price"] } } } }])

B : db.orders.aggregate([ { $unwind: "$items" }, { $group: { _id: "$customer_name", total_sales: { $sum: { $multiply: ["$items.quantity", "$items.price"] } } } }])

C : db.orders.aggregate([ { $unwind: "$items" }, { $group: { total_sales: { $sum: { $multiply: ["$items.quantity", "$items.price"] } } } }])

D : db.orders.aggregate([ { $unwind: "$items" }, { $group: { _id: "$customer_name", total_sales: { $sum: { $multiply: ["quantity", "price"] } } } }])

Answer: B

Question 3

Suppose you have a products collection with an index:{ product_category: 1 }For which of the following queries can MongoDB look at only a subset of the index entries, rather than all of the index entries?

A : db.products.find( { product_category: /A$/ } )

B : db.products.find( { product_category: /A./ } )

C : db.products.find( { product_category: /S./ } )

D : db.products.find( { product_category: /^A./ } )

Answer: D

Question 4

You are developing a blogging platform using MongoDB as the database. Each blog post document has a tags array field that holds a list of strings. You are tasked to implement a search functionality that allows users to find blog posts based on the tags. Which of the following MongoDB features would you utilize to implement this functionality efficiently?

A : Capped Collections

B : Sharding

C : Text Indexes

D : Compound Indexes

E : GridFS

Answer: C

Question 5

Given the following orders collection in MongoDB:[ { "_id": 1, "customer": "John", "orderDetails": [ { "productId": "P1", "quantity": 2, "unitPrice": 50 }, { "productId": "P2", "quantity": 1, "unitPrice": 30 } ] }, { "_id": 2, "customer": "Sara", "orderDetails": [ { "productId": "P1", "quantity": 3, "unitPrice": 50 }, { "productId": "P3", "quantity": 2, "unitPrice": 20 } ] }, { "_id": 3, "customer": "Peter", "orderDetails": [ { "productId": "P2", "quantity": 2, "unitPrice": 30 }, { "productId": "P4", "quantity": 1, "unitPrice": 100 } ] }]Which MongoDB query will find all orders that contain a product with the productId of "P1" and a quantity greater than 1?

A : db.orders.find( { orderDetails: { $elemMatch: { productId: "P1", quantity: { $gt: 1 } } } } )

B : db.orders.find( { "orderDetails.productId": "P1", "orderDetails.quantity": { $gt: 1 } } )

C : db.orders.find( { orderDetails: { $elemMatch: { productId: "P1", quantity: { $gte: 1 } } } } )

D : db.orders.find( { "orderDetails.productId": "P1", "orderDetails.quantity": { $eq: 2 } } )

Answer: A

Free MongoDB C100DEV Practice Exam Questions and Answers 2026