MongoDB MongoDB Certifications C100DBA Questions & Answers

• Question 61:

  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?

  

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

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

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

  Correct Answer: C

• Question 62:

  Which of the following collections stores authentication credentials in MongoDB?

  A. test.users

  B. local.users

  C. system.users

  D. users.users

  Correct Answer: C

• 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?

  Correct Answer: D

• Question 64:

  In which of the following scenarios is sharding not the correct option. Select all that apply.

  A. The write operations on the collection are low

  B. The write operations on the collection are very high

  C. The working set in the collection is expected to grow very large in size

  D. The collection is a read intensive collection with less working set

  Correct Answer: AD

• Question 65:

  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

  Correct Answer: C

• Question 66:

  In what format does mongodump creates backup files?

  A. BSON

  B. JSON

  C. SOAP

  D. XML

  Correct Answer: A

• Question 67:

  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:

  A. .oplog.rs

  B. oplog.rs

  C. ..oplog.rs

  D. local.oplog.rs

  Correct Answer: D

• Question 68:

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

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

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

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

  D. Skips the first five documents and returns the next five

  Correct Answer: D

• Question 69:

  What is the maximum size of a MongoDB document

  A. 16 MB

  B. 12 MB

  C. 2 MB

  D. There is no maximum size. It depends on the RAM.

  Correct Answer: A

• Question 70:

  What tool would you use if you want to save a gif file in mongo?

  A. mongofile

  Correct Answer: A