Question

Point out the correct statement.

(a) To facilitate replication, all replica set members send heartbeats (pings) to all other members

(b) For proper replication operations, entries in the oplog must be idempotent

(c) Any member can import oplog entries from any other member

(d) All of the mentioned

The question was asked in an interview.

My enquiry is from Replication Processes topic in portion Replication Concepts, Processes and Replication Set of MongoDB

Answer 1

The correct answer is (b) For proper replication operations, entries in the oplog must be idempotent

The explanation is: When you start a replica set member for the first time, MongoDB creates an oplog of a default size.