MongoDB MongoDB Replication and Sharding

Question 1

What is a replica set in MongoDB?

Accepted Answer

A group of mongod instances maintaining the same data set for redundancy

Answer

A replica set is a group of MongoDB instances that maintain the same data, providing high availability through automatic failover.

Question 2

What is the role of the primary node in a MongoDB replica set?

Accepted Answer

Receives all write operations and records changes to the oplog

Answer

The primary is the only member that receives write operations; it records all changes in its oplog, which secondaries replicate.

Question 3

How many votes are needed for a primary election in a MongoDB replica set?

Accepted Answer

A simple majority of all voting members

Answer

A replica set member wins a primary election by receiving votes from a majority of all voting members, preventing split-brain scenarios.

Question 4

What is an arbiter in a MongoDB replica set?

Accepted Answer

A voting member that holds no data and only participates in elections

Answer

An arbiter participates in primary elections to maintain an odd number of votes but does not replicate data, using minimal resources.

Question 5

What is the oplog in MongoDB replication?

Accepted Answer

A capped collection that records all data-modifying operations on the primary

Answer

The oplog (operations log) is a special capped collection on the primary that records every write operation; secondaries replicate these entries to stay synchronized.

MongoDB Practice Test

MongoDB Practice Test

MongoDB MongoDB Replication and Sharding