C100DBA by MongoDB Valid Free Exam Practice Test

Question 1

Which is the correct order (lowest to highest) in which MongoDB compares the BSON types?

A. Null, Number, Object and String B. String, Null, Number and Object C. Null, Number, String and Object D. Number, Null, String and Object

Correct Answer: C

Question 2

Which of the following collections stores authentication credentials in MongoDB?

A. test.users B. system.users C. users.users D. local.users

Correct Answer: B

Question 3

Which of the following commands finds all the documents in the posts collection with post timestamp field as null?

A. db.posts.find( { post_timestamp: { $fieldtype: null } } ) B. db.posts.find( { post_timestamp: { $type: null } } ) C. db.posts.find( { post_timestamp: { $fieldtype: 10 } } ) D. db.posts.find( { post_timestamp : { $type; 10 > > )

Correct Answer: B

Question 4

Below is a sample document in a given collection test.
{ a : 5, b : 3, c: 2, d : 1 }
Given a compound index { a: 1, b:l, c:l, d:l}, Which of the below query will not use in-memory sorting? Select all valid.

A. db.test.find( { a: 5, b: 3 } ).sort( { c: 1, d : 1 } ) B. db.test.find( { a: 5, b: 3 } ).sort( { a: 1} ) C. db.test.find( { a: 5, b: 3 } ).sort( { a: 1, b: 1, c: 1 } ) D. db.test.find( { a: 5, b: 3 } ).sort( {c: 1 } )

Correct Answer: A,D

Question 5

Given a collection posts as shown below having a document array comments, which of the following command will create an index on the comment author descending?

A. db.posts.createIndex({comments.$.author": {$desc:l>}); B. db.posts.createIndex({commerits.$.author":-l}); C. db.posts.createIndex({comments.author":-l});

Correct Answer: C

Question 6

The MongoDB explain() method does not support which of the following verbosity mode:

A. executionStats B. customExecutionStats C. queryPlanner D. allPlansExecution

Correct Answer: A

Question 7

Which of the following commands will return all the posts with number of likes greater than 100 and less than 200, both inclusive?

A. db.posts.find({ likes : { $gte : 100 , $lte : 200 } } ); B. db.posts.find({ likes : { $gt : 100 , $lte : 200 } } ); C. db.posts.find({ likes : { $gte : 100, $lt : 200 } } ); D. db.posts.find({ likes : { $gt : 100, $lt : 200 > > );

Correct Answer: A

Question 8

You perform the following operation in the shell: db.foo.insert( { } ); What gets inserted?

A. A document that matches the collection's existing schema, but with null fields B. A document with an _id assigned to be an Objectld C. No document will be inserted; an error will be raised D. An empty document E. A document will be inserted with the same _id as the last document inserted

Correct Answer: B

MongoDB Certified DBA Associate Exam (Based on MongoDB 4.4) - C100DBA Exam Practice Test