MongoDB MCQs – Scaling and Monitoring

MongoDB Scaling and Monitoring is crucial for handling large datasets, ensuring high availability, and troubleshooting performance issues in production environments. Topics like replication, sharding, monitoring tools (mongostat, mongotop, Ops Manager), and query profiling are essential for optimizing database performance.

The following MCQs will help you prepare for such interviews by testing your knowledge of MongoDB scaling and monitoring.

1.) Which MongoDB feature ensures high availability by replicating data across multiple servers?

A) Sharding
B) Indexing
C) Replication
D) Aggregation

Answer: Option C

Explanation: Replication ensures high availability by maintaining identical copies of data across multiple servers, preventing data loss in case of failures.

2.) What is the primary purpose of MongoDB sharding?

A) To store documents efficiently
B) To distribute data across multiple machines
C) To increase indexing speed
D) To optimize query performance

Answer: Option B

Explanation: Sharding distributes large datasets across multiple servers, improving scalability and query performance.

3.) Which MongoDB component is responsible for routing queries in a sharded cluster?

A) mongod
B) mongotop
C) mongostat
D) mongos

Answer: Option D

Explanation: The mongos process routes client requests to the appropriate shard in a sharded MongoDB cluster.

4.) What type of MongoDB node can serve read requests in a replica set?

A) Primary node only
B) Secondary node only
C) Both primary and secondary nodes
D) Arbiter node

Answer: Option C

Explanation: Secondary nodes can serve read requests if read preferences are set to allow it.

5.) What is the default heartbeat interval for replica set members in MongoDB?

A) 1 second
B) 2 seconds
C) 10 seconds
D) 30 seconds

Answer: Option B

Explanation: Replica set members send heartbeats (pings) to each other every two seconds. If a heartbeat does not return within 10 seconds, the other members mark the delinquent member as inaccessible.

6.) In a sharded MongoDB cluster, which component tracks the metadata of shard distribution?

A) Config servers
B) Mongos router
C) Primary shard
D) Replication set

Answer: Option A

Explanation: Config servers store metadata about shard distribution and chunk location, ensuring efficient query routing in a sharded environment.

7.) How does an arbiter node help in a MongoDB replica set?

A) Stores data
B) Votes during elections
C) Improves read performance
D) Optimizes indexes

Answer: Option B

Explanation: Arbiter nodes do not store data but help in elections when a new primary needs to be selected.

8.) Which tool provides real-time monitoring of MongoDB query performance?

A) mongoimport
B) mongos
C) mongorestore
D) mongotop

Answer: Option D

Explanation: mongotop shows how much time MongoDB spends reading and writing on a per-collection basis.

9.) How can you optimize MongoDB performance in a high-write workload?

A) Increase index size
B) Use replication and sharding
C) Disable journaling
D) Reduce memory allocation

Answer: Option B

Explanation: Replication ensures availability, while sharding distributes writes across multiple nodes, improving performance.

10.) What does the $match aggregation stage do?

A) Filters documents
B) Groups documents
C) Joins collections
D) Sorts documents

Answer: Option A

Explanation: $match is used in aggregation to filter documents based on specified conditions.

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