IMPORTANT Big Data Hadoop Interview Questions

Question

Big Data Hadoop has been one of the top trending technologies and many people are looking for career in Big Data Hadoop. Let's use this thread for Big Data Hadoop Interview discussion. You can post any doubts, answers, suggestions which would be helpful for the interview. You can also refer to the interview questions here: https://bit.ly/2vOV1uE

Answer 1

Hello.. I read the blog on the Interview Questions. I really found it useful. Waiting for the next updated set of questions. Thanks

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Comments

Hey Rekha, thanks for your feedback. The new set of questions will be updated soon. Until then, you can make use of this post for the interview discussion.

Answer 2

Hello sir, I was going through the interview questions and answers on the blog that you mentioned. I have seen lots of mention of "Namenode". I have recently started learning Hadoop, like 1 day ago and so i am not aware of what a Namenode. Can you please tell me?

Comments

Hey Coral,
NameNode can be considered as a master of the system. It maintains the file system tree and the metadata for all the files and directories present in the system. NameNode is a very highly available server that manages the File System Namespace and controls access to files by clients.

Answer 3

What are the differences between HBase and Relational Database?

Comments

HBase                                                                                     Relational Database
It is schema-less                                                            It is schema-based database
It is column-oriented data store                                      It is row-oriented data store
It is used to store de-normalized data                         It is used to store normalized data
It contains sparsely populated tables                                It contains thin tables
Automated partitioning is done is HBase        There is no such provision or built-in support for
                                                                                                  partitioning

Answer 4

I was asked what is 51% attack. I think its a very rare question. Here's the answer

51% Attack refers to a situation where a group of miners who hold more than 50% of the Network Hash Rate could manipulate with the New transactions (Stopping the transactions to proceed or gaining conformations) or able to reverse the transactions that were recently confirmed and kind of doing Double spend. It is Highly unlikely to be able to do that today but it is possible.

I shared it thinking it would help others.