Interview Questions and answers for Hadoop

1.  What is the difference between a Hadoop database and Relational Database?
2.  What is Hadoop framework?
3.  On What concept the Hadoop framework works?
4.  what is HDFS?
5.  what is MAP REDUCE?
6.  What Mapper does?
7.  What is the InputSplit in map reduce software?
8.  what is meaning Replication factor?
9.  what is the default replication factor in HDFS?
11. what is the typical block size of an HDFS block?
12. what is namenode?
13. How does master slave architecture in the Hadoop?
14. What is compute and Storage nodes?
15. Explain how input and output data format of the Hadoop framework?
16. How can we control particular key should go in a specific reducer?
17. What is the use of Combiner?
18. What is the Reducer used for?
19. What are the primary phases of the Reducer?
20. Explain the shuffle?
21. What happens if number of reducers are 0?
22. How many instances of JobTracker can run on a Hadoop Cluser?
23. How NameNode Handles data node failures?
24. Can I set the number of reducers to zero?