C100DBA Online Practice Questions and Answers

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

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

A. $set

B. $update

C. $project

D. $modify

What is the output of the following program?

A. 60 s

B. 1s

C. 100 s

D. 100 ms

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()

Which are the ONLY ways to project portions of an array?

A. $slice

B. $

C. All of the above

D. $ elemMatch

In what format does mongodump creates backup files?

A. BSON

B. JSON

C. SOAP

D. XML

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

The________operator can be used to identify an element in the array to be updated without explicitly specifying the position of the element.

A. $ elemMatch

B. $slice

C. Updating an array field without knowing its index is not possible.

D. $

Which of the following needs to be performed prior to initiate backup on a sharded cluster?

A. db.stopBalancer( )

B. sh.stopServer( )

C. db.stopServer( )

D. sh.stopBalancer( )

Which is the default mode in which the explain() command runs?

A. allPlansExecution

B. customExecutionStats

C. queryPlanner

D. executionStats

MongoDB is a schema-less design.

A. False

B. True

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

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

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

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

What is the equivalent command in MongoDB for the following SQL query? SELECT * FROM posts WHERE author like "%john%"

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

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

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

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

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

A. Any node

B. replicaset primary node

C. config server node

D. mongos node

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

A. Sharding

B. Indexing

C. Replication

D. Write Concern