MongoDB Certified DBA Associate C100DBA Practice Exam Questions

test2022-03-12T03:53:57+00:00

By test C100DBA exam dumps, C100DBA Practice Exam Questions, MongoDB Certified DBA Associate 0 Comments

Start to prepare for your MongoDB Certified DBA Associate exam? MongoDB Certified DBA Associate Level Exam is for administrators with knowledge of the concepts and mechanics of MongoDB. C100DBA Practice Exam cover real exam questions and answers to help you prepare for the exam well. With real C100DBA dumps, you can learn about the exam topics and pattern fast to better adapt to the exam environment.

You should try C100DBA practice test questions to assess yourself.

Page 1 of 4

1. By default, the MongoDB cursor in mongo shell is configured to return how many documents? To get the next set of documents, which command is used?

200, more

No limit, none

20, it

50, it

2. When should we consider representing a one-to-many relationship in an embedded collection instead of separate collection?

When the many is not very large

When the many is very large

Always

Never

3. 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?

db.posts.createIndex({^comments.$.author":-l});

db. posts.createIndex({^comments.author" :1});

db.posts.createIndex({^commerits.author";-!});

4. Which of the following aggregation commands in MongoDB does not support sharded collections?

mapReduce

group

aggregate

All of the above

5. In a sharded replicas set environment with multiple mongos servers, which of the following would decide the mongos failover?

mongos

mongo shell

individual language drivers

mongod

6. Which of the documents below will be retrieved by the following query? Assume the documents are stored in a collection called "sample". Check all that apply.

db.sample.find( { "$or" : [ { "a" : { "$in" : [ 3, 10] > }, { "b" : { "$lt" : 2 > > ] > )

{''__id" :3, "a": 4, "c" :0, "b" :14}

{''_Jd" :7, "a": 8, "c" :1, "b" :7}

{".Jd" :6, "a": 1, "c" :1, "b" :5}

{ ''Jd" :9, "a": 17, "c": 1, "b": 1}

{ Jd" :10,"a": 3, "c": 1, "b": 1}

{".Jd" :: 2, "a": 2, "c" :: 0, "b": 1}

{".Jd" :: 4, "a": 5, "c" :: 0, "b": 17}

{".Jd" :: 1, "a": 0, "c" :: 0, "b": 2}

{".Jd" :: 5, "a": 3, "c" :: 0, "b": 12}

{".Jd" :: 8, "a": 11, "c": 1, "b": 0}

7. Consider that our posts collection contains an array field called tags that contains tags that the user enters. {

Which of the following commands will find all the posts that have been tagged as tutorial.

db.posts.find( { tags : ["tutorial"] } );

db.posts.find( { $array : {tags: "tutorial") > );

db.posts.find( { tags : "tutorial" } );

db.posts.findInArray( { tags : "tutorial" > );

8. Which operations add new documents to a collection?

Create

update

insert

delete

9. Consider the following example document:

{

"_id": Objectld("5360c0a0a655a60674680bbe"),

"user"

"login": "irOn"

"description": "Made of steel"

"date": ISODate("2014-04-30T09:16:45.836Z"),

}

>

and index creation command:

db.users.createlndex( { "user.login": 1, "user.date": -1 }, "mylndex" )

When performing the following query:

db.users.find( { "user.login": /Air.*/ },

{ "user":1, "_id":0 > ).sort( { "user.date":1 > )

which of the following statements correctly describe how MongoDB will handle the query? Check all that apply.

As an optimized sort query (scanAndOrder = false) using "mylndex" because we are sorting on an indexed field

As an indexed query using "mylndex" because field "user.login" is indexed

MongoDB will need to do a table/collection scan to find matching documents

None of the above

As a covered query using "mylndex" because we are filtering out "_id" and only returning "user.login"

10. Which format/standard is used by MongoDB internally to store documents?

JSON

BSON

B+ Trees

JSON - Extended

Page 2 of 4

11. Which of the following is correct about MongoDB?

MongoDB supports geospatial indexes

MongoDB supports some of the SQL functions

MongoDB uses JSON format to represent documents

MongoDB supports collection joins

12. You have a replicated cluster with 1 primary, 3 secondary, 1 arbiter. One of the secondary is hidden.

What is the replication factor of this replicated cluster?

13. Consider that you have a collection called population which has fields state and city.

Which of the following query will calculate the population grouped by state and city?

db.population.aggregate( [{ $group: { _id: { state: "$state", city: "$city" },pop: { $pop: 1 } } }] )

db.population.aggregate( [{ $group: { _id: { city: "$city" },pop: { $sum: "$pop" } } }] )Multi Document Transaction is not supported by MongoDB

db.population.aggregate( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $sum: "$pop" } } }] )

db.population.aggregate( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $sum: 1 > > >] )

14. If the value of totalKeysExamined is 30000 and the value of totalDocsExamined is 0, which of the following option is correct?

None of the above

The query used an index to fetch the results

The query returned 0 documents

The query returned 30000 documents after scanning the documents

15. The difference between $push and $addToSet is:

$addToSet needs the fields to be already present while $push will work even if the field is not present

$addToSet adds the item to the field only if it does not exist already; while $push pushes the item to the field irrespective of whether it was present or not

$addToSet adds the item to the field only if the new item is of the same datatype

There is no major difference between them. $addToSet is a deprecated version of $push.

16. Which mongodb tool is used to report details on number of database operations in MongoDB?

mongorestore

mongostat

mongodump

mongotop

17. Suposse tou have the following collection with only 2 documents:

If you run an aggregation query and use { $unwind: "$traits" } as the first stage, how many documents will be passed to the next stage of the aggregation pipeline?

18. In a replicated cluster, which of the following node would only be used during an election?

arbiter

primary

hidden

secondary

19. The________operator can be used to identify an element in the array to be updated

without explicitly specifying

the position of the element.

$ elemMatch

$slice

Updating an array field without knowing its index is not possible.

20. You have designed a web application with mongo DB. You have configured replication. The replica set is in place and function properly.

What happens in case of failure?

Switchover needs to be done manually

Failover happens automatically

Switchover happens automatically

Failover needs to be done manually

Page 3 of 4

21. In a collection that contains 100 post documents, what does the following command do? db. posts. find().skip(5).limit(5)

Skip and limit nullify each other. Hence returning the first five documents

Limits the first five documents and then return them in reverse order

Skips the first five documents and returns the sixth document five times

Skips the first five documents and returns the next five

22. In mongodb how do you update a document partially?

$project

$update

$modify

$set

23. Which are the ONLY ways to project portions of an array?

$slice

All of the above

$ elemMatch

24. What is the on-premise solution having functionality equivalent to cloud manager?

Service Manager

Replica Manager

Ops Manager

Journaling

25. Consider the following posts document:

Which of the following queries will return the documents but with only the first two tags in the tags array?

db.posts.find({author:"Tom"».limit({tags:2})

db.posts.find({author:"Tom"».limit($slice:{tags:2>)

Both "db.posts.find({author:"Tom"},{tags:{$slice:2}})" and "db.posts.find({author:"Tom"}).limit($slice: {tags:2})" are valid. $slice works both with projection and limit.

db.posts.find({author:"Tom">,{tags:{$slice:2»)

26. Which of the following is incorrect statement about find and findOne operations in MongoDB?

findQ returns all the documents in a collection while findOne() retrieves only the first one.

find.limit(l) is not the same query as findOne()

findOneQ returns the actual first document retrieved from a collection

findQ and findOneQ returns cursors to the collection documents

27. ‘$set' sets the value of

Code block

Name/value pair

Key

None of the above

28. A collection and a document in MongoDB is equivalent to which of the SQL concepts respectively?

Column and Row

Table and Row

Database and Table

Table and Column

29. Which of the following node is used during election in a replication cluster?

primary

arbiter

hidden

secondary

30. As per the aggregation pipeline optimization concepts, if you have a $sort followed by a $match:

Providing these parameters in any order does not impact the performance

$sort moves before $match

MongoDB does not do any movements by default and will use the order provided

$match moves before $sort

Page 4 of 4

31. Which command is used to determine storage capacity of specific database?

mongotop

dbstats

mongostat

constats

32. Which of the following commands can cause the database to be locked?

All of the above

Inserting data

Map-reduce

Issuing a query

33. What does the totalKeysExamined field returned by the explain method indicate?

Number of documents that match the query condition

Number of index entries scanned

Details the completed execution of the winning plan as a tree of stages

Number of documents scanned

34. 1.Which features of relational database management systems were deliberately omitted in MongoDB and help us to obtain horizontal scalability? Check all that apply.

Multi-statement transactions

Joins

Authentication