MongoDB MongoDB Certifications C100DBA Questions & Answers

• Question 101:

  Which command can be used to rebuild the indexes on a collection in MongoDB?

  A. db.collection.createlndex({relndex:l})

  B. db.collection.reIndex({author:l})

  C. db.collection.relndexQ

  D. db.collection.createIndex({author:l}).reIndex()

  Correct Answer: C

• Question 102:

  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

  Correct Answer: B

• Question 103:

  Which of the following statements are true about the $match pipeline operator? Check all that apply.

  A. You should use it early as possible in the pipeline

  B. It can be used as many time as needed.

  C. It has a sintax similar to findQ commands.

  Correct Answer: ABC

• Question 104:

  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 4member 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

  Correct Answer: A

• Question 105:

  Using an arbiter allows one to easily ensure an odd number of voters in replica sets. Why is this important?

  A. To help in disaster recovery

  B. To protect agains network partitions

  C. To enable certain read preference settings

  D. To add greather redundancy

  E. For more efficient backup operations

  Correct Answer: B

• Question 106:

  What is the output of the following program?

  A. 60 s

  B. 1s

  C. 100 s

  D. 100 ms

  Correct Answer: A

• Question 107:

  Which node in a replica set does accept write operation?

  A. arbiter

  B. hidden

  C. primary

  D. secondary

  Correct Answer: C

• Question 108:

  Which of the following is true about sharding?

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

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

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

  D. Sharding is enabled at the database level

  Correct Answer: B

• Question 109:

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

  A. netLatency

  B. secondaryPreferred

  C. nearest

  D. primaryPreferred

  Correct Answer: C

• Question 110:

  Which operations add new documents to a collection?

  A. Create

  B. update

  C. insert

  D. delete

  Correct Answer: AC