Big Data and Hadoop is a continually changing field and this field requires people to rapidly upgrade their skills, to fit the job requirements for Hadoop jobs. At PrwaTech our Big Data Hadoop Course enables IT/ ITES professionals to seize lucrative opportunities and enhance their career by gaining desired Big Data Analytics skills. Our Big Data Hadoop Course attendees get in detail practical skill set on Hadoop, including its latest and core components, like MapReduce, HDFS, Pig & Hive, Jasper, Sqoop, Impala HBase, Zoopkeeper, Flume, Oozie, Spark and Storm. For extensive hands-on practice, in both Hadoop Admin Training and Hadoop Online Course participants get full access to the virtual-lab and numerous projects and assignments for Big Data certification.
For the interest of Big Data Hadoop Course attendees we constantly prepare and share latest interview questions and preparation tips. If you are applying for a Hadoop job, it is best to go through these Hadoop interview questions that might be asked in your next interview. Stay connected for Part-II of Big Data Hadoop Interview questions and answer series.
1. Why do we need Hadoop?
Day by day a large quantity of unstructured data gets dumped into our machines. The biggest challenge is not to store these large data sets, but to retrieve and analyze this big data in organizations, to add to the problem we data stored at different locations in different machines. This is where a necessity for Hadoop crops up. Hadoop can analyze the data present at different locations in different machines very quickly and in a cost effective manner. It uses MapReduce which divides the query into smaller parts and processes them in parallel.
2. Name the three modes in which Hadoop can run?
The three modes are −
Standalone (local) mode
Fully distributed mode
3. What happens when a Namenode has no data?
A Namenode that has no data cannot be part of the Hadoop cluster.
4. Can we use Apache Kafka without Zookeeper?
No, it is impossible to use Apache Kafka without Zookeeper because if and when the Zookeeper is down Kafka won’t be able to serve client requests.
5. What is the function of ‘jps’ command?
The ‘jps’ command gives the status of deamons which are running Hadoop cluster. Its output mentions the status of datanode, namenode, secondary namenode, Task tracker and Jobtracker.
6. What is the meaning of bag in Pig?
In Apache Pig “Bag in Pig” refers to a collection of tuples.
7. What’s a Hive Metastore?
It is a central repository which stores metadata in external database.
8. What is shuffling in MapReduce?
Shuffling is the process by which the system executes the sort and transfers the map outputs to reducer as inputs.
9. Sate the difference between an HDFS Block and Input Split?
Physical division of data is known as HDFS Block whereas logical division of data is called Split.
10. What will happen if a datanode fails?
If a datanode fails
Namenode and Jobtracker will detect the failure
All tasks will be re-scheduled on the failed node
Namenode will replicate the users data to some other node
11. Explain what is Apache Hadoop YARN?
YARN is an efficient and powerful feature which comes as a part of Hadoop 2.0.YARN. It is a large scale distributed system which runs big data applications.
12. Explain the basic parameters of a Mapper?
Text and IntWritable and LongWritable and Text are the basic parameters of a Mapper.
13. Explain the functionality of conf.setMapper Class?
Conf.setMapperclass sets the mapper class and everything else related to map job including reading data and generating a key-value pair from the mapper.
14. Explain how a Namenode is restarted?
To restart a namenode follow the below steps
Click on stop-all.sh and then click start-all.sh
Write sudo hdfs, su-hdfs, /etc/init.d/ha and then /etc/init.d/hadoop-0.20-namenode start
15. If Namenode is down what would happen to the job tracker?
If Namenode is down, cluster will go OFF, because in HDFS Namenode is the single point of failure.
Big Data Hadoop Course attendees must thoroughly go through these questions and we’ll soon share Part-II of Big Data Hadoop Interview questions and answer series.