MongoDB Certified DBA Associate Exam (Based on MongoDB 4.4) C100DBA Online Free Questions

Posted by: Pdfprep Category: Uncategorized Tags: C100DBA Online Questions Post Date: January 24, 2021

Pdfprep2021-01-24T01:32:27+00:00

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1. What is the output of following two commands in MongoDB: db. posts. insert({n_id":l}) db.posts.insert({"_id":l})

Two documents will be inserted with _id as 1

MongoDB will automatically increment the _id of the second document as 2

This will throw a duplicate key error

It will insert two documents and throw a warning to the user

2. Which of the following command inside aggregate command is used in MongoDB aggregation to filter the documents to pass only the documents that match the specified condition(s) to the next pipeline stage.

$aggregate

$sum

$match

$group

3. What does the following $slice query return using the following command? db.posts.find( {}, { comments: { $slice: [ -10, 5 ] } } )

Returns 5 comments, beginning with the last 10 items

Returns 10 comments, beginning with the last

Returns 10 comments, beginning with the first

Returns 5 comments, beginning with the first 10 items

4. Which of the following are valid json documents? Select all that apply.

{"a":l, "b":{"b":l, "c":"foo", "d":"bar", "e":[l,2,4]}}

{"city":"New York", "population", 7999034, boros:{"queens", "manhattan", "staten island", "the bronx", u "brooklyn"}}

{"name":"Fred Flintstone";"occupation":"Miner";"wife":"Wilma"}

{ }

5. Which of the following is true of the mechanics of replication in MongoDB? Check all that apply.

Members of a replica set may replicate data from any other data-bearing member of the set by default

Clients read from the nearest member of a replica ser by default

Operations on the primary are recorded in a capped collection called the oplog

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

mongotop

dbstats

mongostat

constats

7. Which of the following about Capped Collections is correct?

Fixed Size

Only "Fixed Size" and "High-throughput operations that insert and retrieve documents based on insertion order"

High-throughput operations that insert and retrieve documents based on insertion order

If the allocated space for a capped collection exceeds, it stops inserting new documents

8. Below is a sample document of "orders" collection

MongoDB-C100DBA40_1

$project

9. What is the equivalent command in MongoDB for the following SQL query?

SELECT * FROM posts WHERE author like "%john%"

db.posts.find( { author: /John/ } )

db.posts.find( { author: /AjohnA/ > )

db.posts.find( { $like: {author: /John/} } )

db.posts.find( { author: {$like: /John/} } )

10. Which of the following does MongoDB use to provide High Scalability?

Replication

Write Concern

Indexing

Sharding

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

MongoDB-C100DBA41_1

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" > );

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

All of the above

Inserting data

Map-reduce

Issuing a query

13. Below is a sample document of "orders" collection

MongoDB-C100DBA42_1

$sort

14. To add a new user and enable authentication in MongoDB, which of the following steps

need be executed?

update users collection and restart mongodb

All of the above

update users collection and restart mongodb with -auth option

update users collection and run db.enableAuthenticationQ

15. What does the following aggregate query perform?

MongoDB-C100DBA43_1

Fetches the posts with likes between 100 and 200 and sets their _id as null

Groups the posts by number of likes (101, 102, 103.) by adding 1 every time

Calculates the number of posts with likes between 100 and 200

Fetches the posts with likes between 100 and 200, sets the _id of the first document as null and then increments it 1 every time

16. What does the output x of the following MongoDB aggregation query result into; db.posts.aggregate( [ { $group: { _id; "$author", x: { $sum: $likes } } } ] )

Average of likes on all the posts of an author, grouped by author

Number of posts by an author

Sum of likes on all the posts by all the authors

Sum of likes on all the posts by an author, grouped by author

17. Update If Correct is an approach for which of the following concepts in MongoDB:

Concurrency Control

Atomicity

Performance Management

Transaction Management

18. You have the following index on the toys collection:

{

"manufacturer" : 1,

"name" : 1,

"date" : -1

}

Which of the following is able to use the index for the query? Check all that apply.

db.toys.find( { name : "Big Rig Truck", date : "2013-02-01", manufacturer : "Tanko"

db.toys.find( { manufacturer : "Matteo", name : "Barbara", date : "2014-07-02" } )

db.toys.find( { date : "2015-03-01", manufacturer : "Loggo", name : "Brick Set" } )

19. 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

20. In a sharded cluster, from which node does one stop the balancer process before initiating backup?

Any node

replicaset primary node

config server node

mongos node

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21. CORRECT TEXT

What tool do you use if you want to extract a CSV from mongo?

22. Which type of indexes does MongoDB support?

All of the above

Compound Indexes

Multikey Indexes

Geospatial Indexes

23. The oplog (operations log) is a special capped collection that keeps a rolling record of all operations that modify the data stored in your databases.

All the replica set members contain a copy of the oplog in the following collection:

oplog.rs

<database>..oplog.rs

<replicasetid>.oplog.rs

local.oplog.rs

24. We can insert multiple documents in bulk using which of the following operations:

initializeUnorderedBulk

initializeUnorderedBulkOp

initializeBulk

initializeBulkOp

25. Which of the following does MongoDB use to provide High Availability and fault tolerance?

Sharding

Indexing

Replication

Write Concern

26. 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

27. 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

28. The following aggregation option is used to specify the specific fields that needs to be passed to the next stage of the aggregation pipeline:

$project

$aggregate

$match

$group

29. 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.

Skips the first five documents and returns the next five

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

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

30. CORRECT TEXT

What tool do you use to see if you have a problem in the consumption of disk I / 0?

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31. Which of the following is supported by MongoDB?

Transaction Management

ACID Transactions

Journaling

Relationships between Collections (Primary Key Foreign Key)

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

executionStats

queryPlanner

customExecutionStats

allPlansExecution

33. Consider a collection posts which has fields: Jd, post_text, post_author, post_timestamp, post_tags etc.

Which of the following query retrieves ONLY the key named post_text from the first document retrieved?

db.posts.finOne({},{_id:0, post_text:1})

db.posts.findOne({post_text: 1})

db.posts.find({},{_id:Of post_text:1})

db.posts.finOne«},{post_text:l})

34. In a sharded replica set environment, the w Option provides ability for write concern and j Option provides ability for the data to be written on disk journal. Consider that we have a seven member replica set and we want to assure that the writes are committed to journal.

What should be the value of j?

35. Aggregation Pipelines have a limit of:

2 MB document and 100 MB RAM

16 MB document and 100 MB RAM

No limit on document and 100 MB RAM

2 MB document and no limit on RAM

36. What is the maximum size of a MongoDB document?

2 MB

12 MB

There is no maximum size. It depends on the RA

16 MB

37. 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

38. 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?

MongoDB-C100DBA5_1

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

db.posts.createIndex({comments.$.author": {$desc:l>});

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

39. Which option should be used to update all the documents with the specified condition in the MongoDB query?

specify {all: true} as the third parameter of update command

updateAII instead of update

specify {updateAII: true} as the third parameter of update command

specify {multi: true} as the third parameter of update command

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

mongorestore

mongostat

mongodump

mongotop

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41. In a sharded replica set environment, the w Option provides ability for write concern and j Option provides ability for the data to be written on disk journal. Consider that we have a seven member replica set and we want to assure that the writes are committed to journal.

What should be the value of j?

42. What read preference should your application use if you want to read from the primary under normal circumstances but allow reads from secondaries when a primary is unavailable?

secondaryPreferred

Secondary

nearest

primary

primaryPreferred

43. Which of the following operators is used to updated a document partially?

$set

$update

$project

$modify

44. What is the first task that a secondary would perform on being prompted by another secondary for an election?

Start the election process for primary

Vote for the first secondary so that it would become the next primary

Vote for itself and then call for election

Connect to primary to confirm its availability

45. 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}

46. JSON stands for

JavaScript Object Notation

JavaScript Object Naming

JavaScript Object Notice

None of the above

47. What is the replication factor for a replicated cluster with 1 primary, 3 secondaries with one of them hidden. The set also has an arbiter?

None of the above

48. Which operations add new documents to a collection?

Create

update

insert

delete

49. 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: { $sum: 1 > > >] )

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

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

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

50. Which of the following is true about sharding?

Creating a sharded key automatically creates an index on the collection using that key

We cannot change a shard key directly/automatically once it is set up

A sharded environment does not support sorting functionality since the documents lie on various mongod instances

Sharding is enabled at the database level

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51. Which of the tags in a replica set configuration specify the operations to be read from the node with the least network latency?

netLatency

secondaryPreferred

nearest

primaryPreferred

52. What is the output of the following program?

60 s

100 s

100 ms

MongoDB Certified DBA Associate Exam (Based on MongoDB 4.4) C100DBA Online Free Questions

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