MongoDB C100DBA Online Practice Questions and Exam Preparation

MongoDB C100DBA Online Questions & Answers

• Question 61:

  You are in a sharded cluster. What will you do prior to initiating backup in sharded cluster?

  A. db.stopBalancer()
  B. db.stopserver()
  C. sh.stopBalancer()
  D. sh.stopserverQ
  C. sh.stopBalancer()

• Question 62:

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

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

• Question 63:

  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?

  A. db.posts.find({author:"Tom"?limit({tags:2})
  B. db.posts.find({author:"Tom"?limit($slice:{tags:>;)
  C. Both "db.posts.find({author:"Tom"},{tags:{$slice:2}})" and "db.posts.find({author:"Tom"}).limit($slice: {tags:2})" are valid. $slice works both with projection and limit.
  D. db.posts.find({author:"Tom">,{tags:{$slice:2?
  D. db.posts.find({author:"Tom">,{tags:{$slice:2?

• Question 64:

  Below is a sample document of "orders" collection

  

  A. $sort
  A. $sort

• Question 65:

  Given a replica set with five data-bearing members, suppose the primary goes down with operations in its oplog that have been copied from the primary to only one secondary. Assuming no other problems occur, which of the following describes what is most likely to happen?

  A. missing operations will need to be manually re-performed
  B. the secondary with the most current oplog will be elected primary
  C. reads will be stale until the primary comes back up
  D. the primary may roll back the operations once it recovers
  E. the most current secondary will roll back the operations following the election
  B. the secondary with the most current oplog will be elected primary

• Question 66:

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

  A. mapReduce
  B. group
  C. aggregate
  D. All of the above
  B. group

• Question 67:

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

  A. mongorestore
  B. mongostat
  C. mongodump
  D. mongotop
  B. mongostat

• Question 68:

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

  A. mongos
  B. mongo shell
  C. individual language drivers
  D. mongod
  C. individual language drivers

• Question 69:

  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.

  A. db.toys.find( { name : "Big Rig Truck", date : "2013-02-01", manufacturer : "Tanko"
  B. db.toys.find( { manufacturer : "Matteo", name : "Barbara", date : "2014-07-02" } )
  C. db.toys.find( { date : "2015-03-01", manufacturer : "Loggo", name : "Brick Set" } )
  A. db.toys.find( { name : "Big Rig Truck", date : "2013-02-01", manufacturer : "Tanko"
  B. db.toys.find( { manufacturer : "Matteo", name : "Barbara", date : "2014-07-02" } )
  C. db.toys.find( { date : "2015-03-01", manufacturer : "Loggo", name : "Brick Set" } )

• Question 70:

  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?

  A. 3
  B. 5
  C. 4
  D. 2
  E. 1
  B. 5