MongoDB MongoDB Replication and Replica Sets

Question 1

What is the minimum recommended number of members in a MongoDB replica set for high availability?

Accepted Answer

3

Answer

1

Answer

2

Answer

5

Question 2

What is the role of the oplog in MongoDB replication?

Accepted Answer

A capped collection on the primary that records all write operations for secondaries to replicate

Answer

Logging slow queries for performance analysis

Answer

An index of all replica set member statuses

Answer

A write-ahead log for crash recovery

Question 3

How does a MongoDB replica set elect a new primary?

Accepted Answer

Members vote and a candidate must receive a majority of votes

Answer

The oldest secondary automatically becomes primary

Answer

An administrator manually promotes a secondary

Answer

The secondary with the largest oplog becomes primary

Question 4

What is a MongoDB arbiter in a replica set?

Accepted Answer

A member that holds no data but participates in elections to break ties

Answer

A read-only secondary that serves analytics queries

Answer

A delayed secondary used for backup purposes

Answer

A hidden member that is invisible to client connections

Question 5

What is the write concern { w: 'majority' } in MongoDB?

Accepted Answer

Writes are acknowledged after being written to a majority of voting replica set members

Answer

Writes are acknowledged after being written to the primary only

Answer

Writes are replicated to all members before acknowledgment

Answer

Writes are logged to disk but not replicated

Question 6

What happens during a replica set failover when the primary becomes unavailable?

Accepted Answer

An election is held among eligible secondaries to elect a new primary

Answer

All writes are permanently lost

Answer

The replica set becomes read-only until the primary recovers

Answer

Client connections are redirected to a hidden secondary