HDFS Quiz - MCQ - Multiple Choice Questions

Welcome to this multiple-choice quiz on the Hadoop Distributed File System (HDFS). This quiz is designed to help you learn and test your understanding of HDFS, a key part of the Hadoop framework for storing large amounts of data across multiple computers.

In this quiz, you'll find questions covering different aspects of HDFS, such as how it stores data, the roles of important components like NameNode and DataNode, and key features like replication and block size. Each question is followed by an explanation to help you understand the correct answer and learn more about the topic.

This quiz is suitable for beginners who are just starting to learn about HDFS and those who want to review and strengthen their knowledge. The questions are simple yet informative, allowing you to gain confidence in understanding HDFS.

Take your time with each question, read the explanations carefully, and use this quiz as a learning tool to build a solid foundation in HDFS. Enjoy the quiz, and keep learning!

1. What does HDFS stand for?

a) Hadoop Dynamic File System

b) Hadoop Distributed File Store

c) Hadoop Distributed File System

d) Hadoop Dataframe File System

Answer:

c) Hadoop Distributed File System

Explanation:

HDFS stands for Hadoop Distributed File System. It's the primary storage system used by Hadoop applications.

2. In HDFS architecture, which component manages the metadata?

a) DataNode

b) NameNode

c) JobTracker

d) TaskTracker

Answer:

b) NameNode

Explanation:

In HDFS, the NameNode is responsible for storing and managing metadata, while actual data is stored in DataNodes.

3. Which default replication factor does HDFS use for data reliability?

a) 1

b) 2

c) 3

d) 4

Answer:

c) 3

Explanation:

By default, HDFS replicates each block three times to ensure data reliability and fault tolerance.

4. The primary programming language used to develop HDFS is:

a) Python

b) C++

c) Java

d) Ruby

Answer:

c) Java

Explanation:

HDFS is primarily written in Java as part of the Hadoop ecosystem.

5. What is the default block size in HDFS (in Hadoop 2.x)?

a) 32 MB

b) 64 MB

c) 128 MB

d) 256 MB

Answer:

c) 128 MB

Explanation:

In Hadoop 2.x, the default block size for HDFS is 128 MB. This is larger than typical file systems to minimize the cost of seeking and efficiently handle large datasets.

6. In the context of HDFS, what does 'Write once, Read many times' imply?

a) Data can only be written once and read once

b) Data, once written, cannot be modified but can be read multiple times

c) Data can be written multiple times but read only once

d) Both read and write operations are restricted

Answer:

b) Data, once written, cannot be modified but can be read multiple times

Explanation:

This design principle means that HDFS data files are primarily immutable. This minimizes data coherency issues and optimizes data retrieval operations.

7. What role does the Secondary NameNode play in HDFS?

a) It acts as a backup for the Primary NameNode

b) It handles data storage

c) It processes client requests

d) It manages the replication factor

Answer:

a) It acts as a backup for the Primary NameNode

Explanation:

The Secondary NameNode periodically merges the changes (edits) with the filesystem image (fsimage) and creates a new fsimage. While it helps in creating checkpoints, it's not a failover for the primary NameNode.

8. DataNodes in HDFS periodically send which of the following to the NameNode?

a) Block counts

b) Heartbeats

c) Metadata

d) Replication factor updates

Answer:

b) Heartbeats

Explanation:

DataNodes send heartbeats to the NameNode to signal that they are operational. If the NameNode doesn't receive a heartbeat from a DataNode after a certain period, it marks the DataNode as unavailable.

9. Which of the following operations is NOT supported by HDFS?

a) Data replication

b) File delete

c) File rename

d) Random write to an existing file

Answer:

d) Random write to an existing file

Explanation:

HDFS follows the 'Write once, Read many times' model, which means data files are immutable after creation. Hence, random writes to existing files are not supported.

10. How many hardware failures is HDFS designed to work with?

a) No hardware failures

b) Only software failures

c) Hardware and software failures

d) Only during scheduled maintenance

Answer:

c) Hardware and software failures

Explanation:

HDFS is designed for fault tolerance. It can handle both hardware and software failures, ensuring data reliability and system availability.

11. What is a DataNode in HDFS?

a) A node that stores actual data blocks

b) A node that manages metadata

c) A node responsible for job tracking

d) A node responsible for resource management

Answer:

a) A node that stores actual data blocks

Explanation:

A DataNode in HDFS is responsible for storing the actual data blocks. DataNodes are the workhorses of HDFS, providing storage and data retrieval services.

12. Which tool can be used to import/export data from RDBMS to HDFS?

a) Hive

b) Flume

c) Oozie

d) Sqoop

Answer:

d) Sqoop

Explanation:

Sqoop is a tool designed to transfer data between Hadoop and relational database systems. It facilitates the import and export of data between HDFS and RDBMS.

13. What is the replication factor in HDFS?

a) The block size of data

b) The number of copies of a data block stored in HDFS

c) The number of nodes in a cluster

d) The amount of data that can be stored in a DataNode

Answer:

b) The number of copies of a data block stored in HDFS

Explanation:

The replication factor in HDFS refers to the number of copies of a data block that are stored. By default, this number is set to three, ensuring data reliability and fault tolerance.

14. What is the function of the fsck command in HDFS?

a) Check the integrity of files in HDFS

b) Format the NameNode

c) Add a new DataNode

d) Start the Hadoop daemons

Answer:

a) Check the integrity of files in HDFS

Explanation:

The fsck command in HDFS is used to check the health and integrity of files stored in the system. It reports any issues found with the file blocks.

15. Which of the following is NOT an HDFS file operation?

a) Create

b) Append

c) Read

d) Update

Answer:

d) Update

Explanation:

HDFS does not support updates to files after they are written. You can create, append, and read files, but not update them in place.