MongoDB C100DBA Online Practice Questions and Exam Preparation

MongoDB C100DBA Online Questions & Answers

• Question 51:

  Which of the following command is used to get all the indexes on a collection?

  A. db.collection.showIndexes()
  B. db.collection.findlndexes()
  C. db.showIndexes()
  D. db.collection.getlndexesQ
  D. db.collection.getlndexesQ

• Question 52:

  Which mongodb tools allow us to work with our data in a human readable format?

  A. mongodump
  B. mongostat
  C. mongoimport
  D. mongoexport
  C. mongoimport
  D. mongoexport

• Question 53:

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

  A. Column and Row
  B. Table and Row
  C. Database and Table
  D. Table and Column
  B. Table and Row

• Question 54:

  Which option can be used with update command so that a new document gets created if no matching document is found based on the query condition?

  A. upsert command instead of update command
  B. {update: true, insert: true} as the third parameter of update command
  C. This has to be handled in application code (Node.js, PHP, JAVA, C#, etc.) and cannot be handled in mongo shell query
  D. Specify {upsert : true } as the third parameter of update command
  D. Specify {upsert : true } as the third parameter of update command

• Question 55:

  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?

  A. db.posts.finOne({},{_id:0, post_text:1})
  B. db.posts.findOne({post_text: 1})
  C. db.posts.find({},{_id:Of post_text:1})
  D. db.posts.finOne珆,{post_text:l})
  A. db.posts.finOne({},{_id:0, post_text:1})

• Question 56:

  Which of the following is a valid Replica Set configuration if you want: 1-Have 3 copies of everything 2- That RS3 is never primary 2- That RSI and RS2 can be primary? You had to see the different configurations, RS3 could be hidden or priority 0 (But not a referee because we need 3 replicas), while RSI and RS2 could NOT have priority 0 or be hidden or anything like that In a 4-member RS RSO , RSI, RS2

  and RS3 + Referee, RSO (primary) falls after some write operations that have replicated RSI and RS2 (but NOT RS3), who can get up as the new primary? The configuration comes and in it we see that RS2 has a hidden: true (or a priority: 0, (I don't remember)

  A. ORS1
  B. ORS2
  C. ORS3
  D. O arbiter
  E. RSO
  A. ORS1

• Question 57:

  Which of the following operator can be used to limit the number of documents in an array field of a document after an update is performed?

  A. $arrayLimit
  B. $push along with $each, $sort and $slice
  C. $removeFromSet
  D. None of the above
  B. $push along with $each, $sort and $slice

• Question 58:

  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.

  A. As an optimized sort query (scanAndOrder = false) using "mylndex" because we are sorting on an indexed field
  B. As an indexed query using "mylndex" because field "user.login" is indexed
  C. MongoDB will need to do a table/collection scan to find matching documents
  D. None of the above
  E. As a covered query using "mylndex" because we are filtering out "_id" and only returning "user.login"
  B. As an indexed query using "mylndex" because field "user.login" is indexed

• Question 59:

  In a replica set, a_________number of members ensures that the replica set is always able to select a primary.

  A. Even
  B. Odd
  C. 2
  D. Depends on the application architecture
  B. Odd

• Question 60:

  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?

  A. secondaryPreferred
  B. Secondary
  C. nearest
  D. primary
  E. primaryPreferred
  E. primaryPreferred