MongoDB MongoDB Replication and Replica Sets 2

Question 1

What is a hidden replica set member used for?

Accepted Answer

Serving as a dedicated reporting or analytics node invisible to client applications

Answer

Breaking election ties with an extra vote

Answer

Providing geographic redundancy as a primary candidate

Answer

Storing only indexes, not document data

Question 2

What is replication lag in a MongoDB replica set?

Accepted Answer

The time difference between oplog entries on the primary and their application on a secondary

Answer

The delay in write acknowledgment due to network latency

Answer

The time taken to complete an election

Answer

The difference in document counts between primary and secondary

Question 3

What read preference should be used to always read from the primary in MongoDB?

Accepted Answer

primary

Answer

primaryPreferred

Answer

secondary

Answer

nearest

Question 4

A delayed replica set member with a delay of 1 hour is useful for:

Accepted Answer

Providing a point-in-time recovery window to recover from accidental data deletions

Answer

Improving read performance in disaster recovery scenarios

Answer

Serving as a tiebreaker in elections

Answer

Reducing primary write latency

Question 5

What does rs.status() return in the MongoDB shell?

Accepted Answer

The current status of all replica set members including health, state, and replication lag

Answer

A list of all databases in the replica set

Answer

The oplog size and usage statistics

Answer

A summary of active connections to each member

Question 6

Which write concern provides the lowest durability but the highest write throughput in MongoDB?

Accepted Answer

{ w: 0 }

Answer

{ w: 'majority' }

Answer

{ w: 1 }

Answer

{ w: 'all' }