In this Apache Hadoop Interview Questions blog, we are going to cover all the frequently asked Hadoop questions that will help you to crack the interview.
This conclusive list of top Hadoop interview questions will take you through the questions and answers around Apache Hadoop and its ecosystem components i.e HDFS, MapReduce, Hive, YARN, Pig, HBase etc. This blog is the doorway to your next Hadoop job.
In case you have confusion about any Hadoop interview questions and answers, kindly put those questions in the comment section below. We will be glad to answer them.
Top 50 Apache Hadoop Interview Questions and Answers
1) What is Apache Hadoop? Why is Hadoop essential for every Big Data application?
2) What are the main features and Characteristics of Hadoop which makes it the most popular and powerful Big Data tool?
3) What are the core components of Apache Hadoop?
4) What are the configuration files in Hadoop?
5) What are the different modes in which we can configure/install Hadoop?
6) Explain how Hadoop cluster hardware planning and provisioning is done?
7) How to create a user in Hadoop?
8) What are the major differences between Hadoop 2 and Hadoop 3?
9) What is single node cluster in Hadoop? for what all purposes Hadoop run on a single node cluster?
10) How to specify more than one path for storage in Hadoop
11) What is a single point of failure in Hadoop 1 and how is it resolved in Hadoop 2?
12) What is JSP? Why is it used in Hadoop?
13) What is the difference between Apache Hadoop and RDBMS?
14) What is HDFS – Hadoop Distributed File System?
15) What is the key difference between NameNode and DataNode in Hadoop?
16) What do you mean by metadata in HDFS? Where is it stored in Hadoop?
17) What is a block in Hadoop HDFS? What should be the block size to get optimum performance from the Hadoop cluster?
18) What is Small File Problem in Hadoop? How can it be resolved?
19) Why HDFS performs replication, although it results in data redundancy?
20) What is the procedure to create users in HDFS and how to allocate Quota to them?
21) Why HDFS stores data using commodity hardware despite the higher chance of failures?
22) Ideally what should be replication factor in a Hadoop cluster?
23) What is NameNode? How NameNode tackle Datanode failures in Hadoop?
24) Does HDFS allow a client to read a file which is already opened for writing?
25) How does HDFS ensure Data Integrity of data blocks stored in HDFS?
26) How often DataNode send heartbeat to NameNode in Hadoop?
27) What happens if the block in HDFS is corrupted?
28) If I create a folder in HDFS, will there be metadata created corresponding to the folder? If yes, what will be the size of metadata created for a directory?
29) How data or file is read in HDFS?
30) Can multiple clients write into an HDFS file concurrently?
31) How to change the replication factor of data which is already stored in HDFS?
32) How HDFS client divide the file into the block while storing inside HDFS?
33) What is throughput? How does HDFS provide good throughput?
34) What is MapReduce in Hadoop?
35) What is the need of MapReduce in Hadoop?
36) What is Mapper? How can we compress Mapper output in Hadoop?
37) How to set the number of mappers for a MapReduce job?
38) Explain the sequence of execution of all the components of MapReduce like a map, reduce, recordReader, split, combiner, partitioner, sort, shuffle.
39) What is the difference between Reducer and Combiner in Hadoop MapReduce?
40) How to configure the number of the Combiner in MapReduce?
41) In MapReduce how to change the name of the output file from part-r-00000?
42) How to create a custom key and custom value in MapReduce Job?
43) How to optimize MapReduce Job?
44) How to specify more than one directory as input to the MapReduce Job?
45) What is Rack Awareness? What is its need in Hadoop?
46) How is security achieved in Apache Hadoop?
47) What is Erasure Coding in Hadoop?
48) Why do we need Hadoop Archives? How is it created?
49) What is Slot in Hadoop v1? Why was it removed from Hadoop v2?
50) What is CAP Theorem? What aspects does Hadoop support from this theorem?