Top 50 Hadoop Interview Questions with Answers

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1. What is Hadoop?

a) A programming language
b) A software framework
c) A database management system
d) A data visualization tool

Answer: b) A software framework

2. Which of the following is not a component of Hadoop?

a) HDFS
b) MapReduce
c) Spark
d) YARN

Answer: c) Spark

3. What is HDFS?

a) Hadoop Distributed File System
b) Hadoop Data Formatting System
c) Hadoop Data Flow System
d) Hadoop Data Filtering System

Answer: a) Hadoop Distributed File System

4. What is MapReduce?

a) A component of Hadoop used for data processing
b) A programming language used for web development
c) A database management system
d) A data visualization tool

Answer: a) A component of Hadoop used for data processing

5. What is the default block size of HDFS?

a) 64 MB
b) 128 MB
c) 256 MB
d) 512 MB

Answer: b) 128 MB

6. Which programming language is used in Hadoop MapReduce?

a) Java
b) Python
c) C++
d) Ruby

Answer: a) Java

7. What is a NameNode in Hadoop?

a) The node that stores the data
b) The node that manages the cluster and stores metadata about HDFS
c) The node that runs the MapReduce jobs
d) The node that handles network traffic

Answer: b) The node that manages the cluster and stores metadata about HDFS

8. Which of the following is responsible for resource management in Hadoop?

a) HDFS
b) MapReduce
c) YARN
d) NodeManager

Answer: c) YARN

9. Which of the following is not a role in Hadoop?

a) NameNode
b) DataNode
c) JobTracker
d) TaskManager

Answer: d) TaskManager

10. Which component in Hadoop is responsible for data processing?

a) NameNode
b) DataNode
c) JobTracker
d) TaskTracker

Answer: d) TaskTracker

11. What is a block in Hadoop?

a) A group of files
b) A unit of data stored in HDFS
c) A node in the cluster
d) A data processing job

Answer: b) A unit of data stored in HDFS

12. Which of the following is not a benefit of Hadoop?

a) Scalability
b) Data security
c) Fault tolerance
d) High availability

Answer: b) Data security

13. What is the maximum number of NameNodes in a Hadoop cluster?

a) 1
b) 2
c) 3
d) Unlimited

Answer: a) 1

14. What is a secondary NameNode in Hadoop?

a) A backup NameNode used in case the primary NameNode fails
b) A node that handles network traffic
c) A node that stores metadata about the cluster
d) A node that manages MapReduce jobs

Answer: a) A backup NameNode used in case the primary NameNode fails

15. Which of the following is used to write MapReduce jobs in Python?

a) PyMapReduce
b) Hadoop Streaming
c) Hadoop Pipes
d) Hadoop Java API

Answer: b) Hadoop Streaming

16. What is the default port for the Hadoop NameNode web UI?

a) 50070
b) 60010
c) 8080
d) 9000

Answer: a) 50070

17. Which of the following is not a characteristic of Big Data?

a) Volume
b) Variety
c) Velocity
d) Value

Answer: d) Value

18. Which of the following is not a Hadoop ecosystem project?

a) Hive
b) HBase
c) Pig
d) Spark

Answer: d) Spark

19. What is ZooKeeper in Hadoop?

a) A component that manages the metadata of HDFS
b) A tool used for building distributed systems
c) A query engine used for data analysis
d) A data storage platform

Answer: b) A tool used for building distributed systems

20. Which of the following is a data warehouse system for Hadoop?

a) Hive
b) Pig
c) HBase
d) ZooKeeper

Answer: a) Hive

21. What is a data node in Hadoop?

a) A node that manages metadata about HDFS
b) A node that manages MapReduce jobs
c) A node that stores data in HDFS
d) A node that handles network traffic

Answer: c) A node that stores data in HDFS

22. Which of the following is not a database management system?

a) MySQL
b) Oracle
c) MongoDB
d) Spark

Answer: d) Spark

23. What is a block replica in Hadoop?

a) A backup copy of a block of data stored in HDFS
b) A processing unit in MapReduce
c) A tool used for data visualization
d) A database management system for Hadoop

Answer: a) A backup copy of a block of data stored in HDFS

24. What is a decommission in Hadoop?

a) The process of adding a new node to the cluster
b) The process of removing a node from the cluster
c) The process of scaling up the cluster
d) The process of scaling down the cluster

Answer: b) The process of removing a node from the cluster

25. Which of the following is not a characteristic of a distributed system?

a) Scalability
b) Fault tolerance
c) Compatibility
d) Reliability

Answer: c) Compatibility

26. What is the default replication factor in Hadoop?

a) 1
b) 2
c) 3
d) 4

Answer: c) 3

27. What is a task in MapReduce?

a) A processing unit that performs a specific operation on the data
b) A processing unit that stores the data
c) A processing unit that manages the metadata of the cluster
d) A processing unit that handles network traffic

Answer: a) A processing unit that performs a specific operation on the data

28. Which of the following is used for data analysis in Hadoop?

a) Pig
b) HBase
c) ZooKeeper
d) YARN

Answer: a) Pig

29. What is HBase in Hadoop?

a) A platform for real-time data processing
b) A query engine for data analysis
c) A data storage system
d) A tool used for building distributed systems

Answer: c) A data storage system

30. What is a reducer in MapReduce?

Answer: d) A processing unit that combines the output from the mappers

31. Which of the following statements is true about Hadoop Distributed Cache?

a) It is used to store metadata about HDFS
b) It is used to store intermediate data during MapReduce jobs
c) It is used to cache files needed by the MapReduce jobs
d) It is used to compress data stored in HDFS

Answer: c) It is used to cache files needed by the MapReduce jobs

32. What is a combiner in MapReduce?

Answer: d) A processing unit that performs a local reduction on the output from the mappers

33. Which of the following is a way to optimize MapReduce jobs?

a) Combiners
b) Distributed Cache
c) Replication
d) Decommissioning

Answer: a) Combiners

34. What is a data block scanner in Hadoop?

a) A tool used to scan the metadata of HDFS
b) A tool used to scan the data stored in HDFS for errors
c) A tool used to scan the output from MapReduce jobs
d) A tool used to scan the input to MapReduce jobs

Answer: b) A tool used to scan the data stored in HDFS for errors

35. Which of the following is not a characteristic of Hadoop Distributed File System (HDFS)?

a) Scalability
b) Fault tolerance
c) Consistency
d) High availability

Answer: c) Consistency

36. What is an EC2 instance in Hadoop?

a) A type of virtual machine used in Hadoop
b) A database management system for Hadoop
c) A tool used for building distributed systems
d) A programming language used in Hadoop

Answer: a) A type of virtual machine used in Hadoop

37. How does Hadoop ensure fault tolerance?

a) By replicating data across multiple nodes in the cluster
b) By compressing data stored in HDFS
c) By optimizing MapReduce algorithms
d) By using a distributed file system

Answer: a) By replicating data across multiple nodes in the cluster

38. Which of the following is a way to improve the scalability of a Hadoop cluster?

a) Increasing the size of the NameNode
b) Increasing the block size of HDFS
c) Decreasing the replication factor
d) Decreasing the number of nodes in the cluster

Answer: b) Increasing the block size of HDFS

39. What is a slot in Hadoop?

a) A processing unit in MapReduce
b) A node in the cluster
c) A unit of data stored in HDFS
d) A tool used for data visualization

Answer: a) A processing unit in MapReduce

40. Which of the following is not a reason to use Hadoop?

a) Real-time data processing
b) Data storage and retrieval
c) High velocity data processing
d) Querying large datasets

Answer: a) Real-time data processing

41. Which of the following is not a characteristic of Hadoop MapReduce?

a) Scalability
b) Fault tolerance
c) Compatibility
d) High availability

Answer: c) Compatibility

42. What is a queue in YARN?

a) An ordered list of MapReduce jobs
b) A mechanism for resource allocation in YARN
c) A data storage system
d) A tool used for building distributed systems

Answer: b) A mechanism for resource allocation in YARN

43. What is a checkpoint in Hadoop?

a) A backup copy of the metadata in HDFS
b) A processing unit in MapReduce
c) A network traffic analyzer
d) A tool used for data visualization

Answer: a) A backup copy of the metadata in HDFS

44. What is a JobTracker in Hadoop?

a) The node that manages the metadata of HDFS
b) The node that manages MapReduce jobs
c) The node that stores data in HDFS
d) The node that handles network traffic

Answer: b) The node that manages MapReduce jobs

45. Which of the following is not a database management system for Hadoop?

a) Hive
b) HBase
c) Cassandra
d) MapR

Answer: d) MapR

46. What is a TaskTracker in Hadoop?

a) The node that manages the metadata of HDFS
b) The node that manages MapReduce jobs
c) The node that stores data in HDFS
d) The node that handles network traffic

Answer: b) The node that manages MapReduce jobs

47. What is a NameNode in Hadoop?

a) The node that manages the metadata of HDFS
b) The node that manages MapReduce jobs
c) The node that stores data in HDFS
d) The node that handles network traffic

Answer: a) The node that manages the metadata of HDFS

48. Which of the following is not a characteristic of Hadoop YARN?

a) Scalability
b) Fault tolerance
c) Compatibility
d) High availability

Answer: c) Compatibility

49. What is a container in YARN?

a) A mechanism for resource allocation
b) A node in the Hadoop cluster
c) A processing unit in MapReduce
d) A data storage system

Answer: a) A mechanism for resource allocation

50. Which of the following is not a way to optimize MapReduce jobs?

a) Replication
b) Combiners
c) Distributed Cache
d) Partitioning

Answer: a) Replication

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Ashwani Kumar

Sr. Software Engineer at Cotocus Private Limited

There is no end to education. It is not that you read a book, pass an examination, and finish with education. The whole of life, from the moment you are born to the moment you die, is a process of learning.