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The Ultimate Cheat Sheet On Hadoop

Top 20 frequently asked questions to test your Hadoop knowledge given in the below Hadoop cheat sheet. Try finding your own answers and match the answers given here.




Question #1 

You have written a MapReduce job that will process 500 million input records and generate 500 million key-value pairs. The data is not uniformly distributed. Your MapReduce job will create a significant amount of intermediate data that it needs to transfer between mappers and reducers which is a potential bottleneck. A custom implementation of which of the following interfaces is most likely to reduce the amount of intermediate data transferred across the network?



A. Writable
B. WritableComparable
C. InputFormat
D. OutputFormat
E. Combiner
F. Partitioner
Ans: e




Question #2 

Where is Hive metastore stored by default ?


A. In HDFS
B. In client machine in the form of a flat file.
C. In client machine in a derby database
D. In lib directory of HADOOP_HOME, and requires HADOOP_CLASSPATH to be modified.
Ans: c




Question…
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Frequently asked questions on Hadoop security

The below are the list of frequently asked questions on hadoop security. Useful to learn for your data science project and for interviews.

Frequently Asked Questions

  1. How does Hadoop security work?
  2. How do you enforce access control to your data?
  3. How can you control who is authorized to access, modify, and stop Hadoop MapReduce jobs?
  4. How do you get your (insert application here) to integrate with Hadoop security controls?
  5. How do you enforce authentication for users on all types of Hadoop clients (for example, web consoles and processes)?
  6. How can you ensure that rogue services don't impersonate real services (for example, rogue TaskTrackers and tasks, unauthorized processes presenting block IDs to DataNodes to get access to data blocks, and so on)?
  7. Can you tie in your organization's Lightweight Directory Access Protocol (LDAP) directory and user groups to Hadoop's permissions structure?
  8. Can you encrypt data in transit in Hadoop?
  9. Can your data be encrypted at rest on HDFS?
  10. How can you apply consistent security controls to your Hadoop cluster?
  11. What are the best practices for security in Hadoop today?
  12. Are there proposed changes to Hadoop's security model? What are they?

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