Top 50 Hadoop Interview Questions For 2021


In this Apache Hadoop Interview Questions article, we will cover much of the time asked Hadoop Interview Questions and Answers that will assist you with cracking the interview. 

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Top 50 Hadoop Scenario Based Interview Questions For 2021

Following are the frequently asked Hadoop interview questions for experienced as well as Hadoop interview questions for freshers:

1. What is Hadoop?

It is an open-source software system that offers an abundance of services and tools to store and deal with Big Data, and it is one of the Hadoop basic interview questions.

2. What do you think about YARN?

It represents Yet Another Resource Negotiator, and it is the Hadoop preparing system.

3. Input Formats are there in Hadoop?

Three input formats in Hadoop are Key-Value Input Format, Sequence File Input Format, and Text Input Format.

4. What do you comprehend by “Rack Awareness”?

It is described as the algorithm through which NameNode decides how the blocks and their imitations are put away in the Hadoop cluster.

5. Concepts utilized in the Hadoop Framework?

Two core concepts are HDFS and MapReduce.

6. Organizations that are utilizing Hadoop?

Twitter, eBay, Netflix, Spotify, Adobe, Amazon, Facebook, Yahoo, etc.

7. How might you separate Hadoop and RDBMS?

Hadoop can store any sort of data, while RDBMS is made to store structured data.

8. Significant highlights of Hadoop.

It’s designed on Google MapReduce, and it is a frequently asked Hadoop interview question.

9. What do you think about Speculative Execution?

It is an interaction that happens during the slower execution of a task at a node.

10. What are the Components of Apache HBase?

ZooKeeper, HMaster, and Region Server.

11. What are the various schedulers accessible in Hadoop?

Fair Sharing, FIFO Scheduler, and COSHH is one type of Hadoop interview questions.

12. Think about active and passive NameNodes?

Active NameNode runs in the Hadoop cluster, while Passive NameNode stores the very data from the Active NameNode.

13. The contrasts between Hadoop 1 and Hadoop 2?

In Hadoop 1, there is a solitary NameNode, while in Hadoop 2, there are Active and Passive NameNodes.

14. What would it be a good idea for you to consider while deploying a secondary NameNode?

It ought to be deployed on a different Standalone framework consistently.

15. Define “Checkpointing.”

Checkpointing is a methodology that compacts a FsImage and Edit sign into another FsImage.

16. What are the Hadoop daemons?

The Hadoop daemons are JobHistoryServer, ResourceManager, NodeManager, DataNode, Secondary NameNode, and NameNode.

17. Can NameNode and DataNode be commodity hardware?

NameNode is the master node, while DataNodes are the commodity hardware.

18. Elements of Job Tracker.

It manages the life cycle of tasks, tracks the resources, and manages the resources.

19. What is SequenceFile?

It is characterized as a flat file that contains value pairs or a binary key.

20. What are the fundamental Hadoop tools?

Oozie, NoSQL, NoSQL, HDFS, etc.

21. The significant properties of hdfs-site.xml?

checkpoint.dir, name.dr, and data.dr

22. OS supported by Hadoop.


23. Modes in which Hadoop code can be run.

Standalone, Pseudo, and Fully modes.

24. Separate Input Split and HDFS Block.

Input Split is a logical division, while HDFS Block is a physical division, and it is another Hadoop interview question.

25. Is HDFS fault-tolerant?


26. What is the block in HDFS?

Location on the hard drive that is accessible to store data.

27. How is HDFS not the same as NAS?

HDFS is a distributed file framework that stores data, while NAS is only a file-level server for data storage, and it is another Hadoop interview question.

28. What is the utilization of the “jps” command?

It is utilized to check the Hadoop daemons are in a running state.

29. What are the basic Hadoop shell orders utilized for Copy operation?

fs –copyToLocal, fs –put, fs –copyFromLocal.

30. What is a Node Manager?

It is the YARN compared to the task tracker.

31. Is there any valid reason why we shouldn’t utilize HDFS for storing a ton of little size files?

It is appropriate for storing a humongous measure of data in a solitary file.

32. What are the five V’s of Big Data?

Volume, Veracity, Velocity, Variety, and Value.

33. Clarify Hadoop architecture?

It is a cluster that contains a solitary Master hub or NameNode.

34. Do two users attempt to get to a similar file in HDFS?


35. GPU Hardware Usage?

Hadoop 3 uses GPU hardware inside a Hadoop cluster.

36. Explain SequenceFileInputFormat?

It is a proficient transition for data passing from one MapReduce to the next.

37. What do you comprehend by Combiner in Hadoop?

It upgrades the effectiveness of MapReduce.

38. Explain a MapReduce Partitioner?

It helps inequitably convey the map output over the reducers.

39. Does MapReduce permit reducers to speak with each other?


40. For what reason do we need RecordReader in Hadoop?

For loading the data from its source.

41. Define MapReduce.

MapReduce is a programming model.

42. What are the default block sizes in Hadoop 1, 2, and 3?

Hadoop 1 is 64 MB, while Hadoop 2 and 3 is 128 MB.

43. Explain the role of a Job Tracker in Hadoop?

Tracking resource availability, Task lifecycle management, and Resource management.

44. Explain the center methods for a Reducer?

setup(), reduce(), and cleanup().

45. Hadoop Applications

Data discovery and massive storage.

46. Example of Structured data.

PostgreSQL databases, Datastore in SQL, Schema-based data, etc.

47. Example of Semi-structured data.

Tweets, weblogs, xlsx files, txt, csv, etc.

48. Example of Unstructured data.

Video, Audio files, etc.

49. What are the Components of Data Access?

Pig and Hive

50. What is the Component of Data Storage?



That summarizes our rundown of the top 50 Hadoop interview questions. Expectations are you tracked down these supportive for getting ready for your impending interview or simply checking your advancement in learning Hadoop.

Christophe Rude
Christophe Rude
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