1. What is MongoDB?
a. A relational database
b. A NoSQL database
c. A graph database
d. A file system
Answer: b. A NoSQL database
2. In MongoDB, what is a document?
a. A record in a table
b. A field in a collection
c. A JSON-like data structure
d. A row in a database
Answer: c. A JSON-like data structure
3. What is the default port for MongoDB?
a. 3306
b. 27017
c. 5432
d. 8080
Answer: b. 27017
4. Which data format is used in MongoDB for storage and data exchange?
a. XML
b. JSON
c. BSON
d. YAML
Answer: c. BSON
5. What is a Collection in MongoDB?
a. A group of related documents
b. A set of fields
c. A single document
d. A table in a relational database
Answer: a. A group of related documents
6. What is the purpose of the _id field in MongoDB?
a. It is a reserved keyword
b. It must be manually added to each document
c. It is automatically added to each document as a unique identifier
d. It is used only for indexing
Answer: c. It is automatically added to each document as a unique identifier
7. How can you update a document in MongoDB?
a. db.collection.update()
b. db.collection.modify()
c. db.collection.save()
d. db.collection.edit()
Answer: a. db.collection.update()
8. What does the $set operator do in MongoDB?
a. Adds a new field to a document
b. Removes a field from a document
c. Updates a field with a new value
d. Replaces the entire document
Answer: c. Updates a field with a new value
9. What does the $elemMatch operator do in MongoDB?
a. Matches documents based on an element in an array
b. Adds a new element to an array
c. Removes an element from an array
d. Sorts elements in an array
Answer: a. Matches documents based on an element in an array
10. What is the purpose of the mongod process in MongoDB?
a. It is the MongoDB shell
b. It is the MongoDB server
c. It is the MongoDB router
d. It is the MongoDB driver
Answer: b. It is the MongoDB server
11. How can you create an index in MongoDB?
a. db.collection.createIndex()
b. db.createIndex()
c. db.collection.addIndex()
d. db.addIndex()
Answer: a. db.collection.createIndex()
12. What is Sharding in MongoDB?
a. Document validation
b. Data replication
c. Data partitioning
d. Database encryption
Answer: c. Data partitioning
13. What does the $push operator do in MongoDB?
a. Updates documents
b. Adds elements to an array
c. Removes elements from an array
d. Creates a new collection
Answer: b. Adds elements to an array
14. In MongoDB, what is the purpose of the mongos process?
a. It is the MongoDB shell
b. It is the MongoDB server
c. It is the MongoDB router
d. It is the MongoDB driver
Answer: c. It is the MongoDB router
15. How can you enable authentication in MongoDB?
a. Start mongod with the --auth option
b. Use the enableAuth() method
c. Set the authentication flag in the configuration file
d. Authentication is enabled by default
Answer: a. Start mongod with the --auth option
16. What does the MongoDB profiler do?
a. Manages connections to the database
b. Analyzes and optimizes query performance
c. Enforces data validation rules
d. Provides real-time data backups
Answer: b. Analyzes and optimizes query performance
17. What is a covered query in MongoDB?
a. A query that includes all fields of a document
b. A query that can be fulfilled using an index only
c. A query for encryption purposes
d. A query that includes only specific fields
Answer: b. A query that can be fulfilled using an index only
18. What is MongoDB Atlas?
a. A graphical user interface for MongoDB
b. An in-memory storage engine for MongoDB
c. A fully managed cloud database service
d. A standalone MongoDB shell
Answer: c. A fully managed cloud database service
19. What is GridFS used for in MongoDB?
a. Document validation
b. Storing large files by dividing them into smaller chunks
c. Data replication
d. Sharding
Answer: b. Storing large files by dividing them into smaller chunks
20. How do you perform aggregation in MongoDB?
a. Using the $aggregate operator
b. Using the aggregate() method
c. Using the $group operator
d. Aggregation is not supported in MongoDB
Answer: b. Using the aggregate() method
21. What is the purpose of the $pull operator in MongoDB?
a. Adds elements to an array
b. Removes elements from an array
c. Updates documents
d. Replaces the entire document
Answer: b. Removes elements from an array
22. Which operator is used to perform equality matching on arrays in MongoDB?
a. $in
b. $eq
c. $ne
d. $all
Answer: b. $eq
23. What does the db.getCollectionNames() method do in MongoDB?
a. Retrieves the list of databases
b. Retrieves the list of collections in the current database
c. Retrieves the list of documents in a collection
d. Retrieves the list of fields in a document
Answer: b. Retrieves the list of collections in the current database
24. What is the purpose of the $addToSet operator in MongoDB?
a. Adds elements to an array
b. Removes elements from an array
c. Adds elements to an array only if they do not already exist
d. Updates documents
Answer: c. Adds elements to an array only if they do not already exist
25. How can you find distinct values in a field using MongoDB?
a. db.collection.distinct()
b. db.collection.findDistinct()
c. db.distinct()
d. db.findDistinct()
Answer: a. db.collection.distinct()
26. What does the explain() method do in MongoDB?
a. Displays information about the database schema
b. Displays detailed information about the execution of a query
c. Executes a query and displays the result
d. Exports the data in the collection to a file
Answer: b. Displays detailed information about the execution of a query
27. What is the purpose of the $exists operator in MongoDB?
a. Matches documents where a field does not exist
b. Matches documents where a field exists
c. Matches documents based on the existence of an array
d. Matches documents based on the absence of a specific field
Answer: b. Matches documents where a field exists
28. How can you sort the results of a query in descending order in MongoDB?
a. db.collection.sort({field: -1})
b. db.collection.orderBy({field: -1})
c. db.collection.find().sort({field: -1})
d. db.collection.find().orderBy({field: -1})
Answer: c. db.collection.find().sort({field: -1})
29. Which of the following is true about the $regex operator in MongoDB?
a. It is used for adding regular expressions to documents
b. It is used for searching text within documents using regular expressions
c. It is used for updating documents with regular expressions
d. It is used for removing regular expressions from documents
Answer: b. It is used for searching text within documents using regular expressions
30. What is the purpose of the mongorestore tool in MongoDB?
a. It is used to export data from MongoDB
b. It is used to query the MongoDB database
c. It is used to restore a previously created MongoDB database backup
d. It is used to create a new MongoDB collection
Answer: c. It is used to restore a previously created MongoDB database backup
31. What does the $and operator do in MongoDB?
a. Performs a logical AND operation on an array of expressions
b. Adds elements to an array
c. Removes elements from an array
d. Performs a logical OR operation on an array of expressions
Answer: a. Performs a logical AND operation on an array of expressions
32. How do you remove documents from a collection in MongoDB?
a. db.collection.delete()
b. db.collection.remove()
c. db.collection.drop()
d. db.collection.truncate()
Answer: b. db.collection.remove()
33. What is the purpose of the $slice operator in MongoDB?
a. To slice arrays within documents
b. To slice documents within a collection
c. To slice fields within documents
d. To slice collections within a database
Answer: a. To slice arrays within documents
34. Which of the following is a valid projection in MongoDB?
a. db.collection.find({}, {field1: 1, field2: 0})
b. db.collection.find({}, {field1: true, field2: false})
c. db.collection.find({}, {field1: include, field2: exclude})
d. db.collection.find({}, {field1: "include", field2: "exclude"})
Answer: b. db.collection.find({}, {field1: true, field2: false})
35. What is the purpose of the mongotop tool in MongoDB?
a. It is used to perform aggregation on MongoDB collections
b. It is used to monitor disk I/O
c. It is used to monitor MongoDB server operations
d. It is used to export data from MongoDB to a file
Answer: c. It is used to monitor MongoDB server operations
36. How can you limit the number of documents returned in a MongoDB query?
a. db.collection.limit(5)
b. db.collection.find().limit(5)
c. db.collection.setLimit(5)
d. db.collection.find().setLimit(5)
Answer: b. db.collection.find().limit(5)
37. What is the purpose of the mongodump tool in MongoDB?
a. It is used to import data into MongoDB
b. It is used to query the MongoDB database
c. It is used to create a backup of a MongoDB database
d. It is used to delete data from MongoDB
Answer: c. It is used to create a backup of a MongoDB database
38. What is the purpose of the $sum operator in MongoDB Aggregation?
a. To calculate the average value of a field
b. To concatenate strings in a field
c. To count the number of documents
d. To calculate the sum of numeric values in a field
Answer: d. To calculate the sum of numeric values in a field
39. Which method is used to create an index on multiple fields in MongoDB?
a. db.collection.createIndex({field1: 1, field2: 1})
b. db.collection.createIndex({field1: "asc", field2: "asc"})
c. db.collection.createIndex({field1: "asc", field2: "desc"})
d. db.collection.createIndex({field1: 1}, {field2: 1})
Answer: a. db.collection.createIndex({field1: 1, field2: 1})
40. What is the purpose of the $out stage in MongoDB Aggregation?
a. To append documents to an existing collection
b. To create a new collection with the aggregated results
c. To update existing documents in a collection
d. To remove documents from a collection
Answer: b. To create a new collection with the aggregated results
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