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Big Data Interview Questions and Answers

Big Data Interview Questions and Answers

Question - 1 : - What do you know about the term “Big Data”?

Answer - 1 : - Big Data is a term associated with complex and large datasets. A relational database cannot handle big data, and that’s why special tools and methods are used to perform operations on a vast collection of data. Big data enables companies to understand their business better and helps them derive meaningful information from the unstructured and raw data collected on a regular basis. Big data also allows the companies to take better business decisions backed by data.

Question - 2 : - What are the five V’s of Big Data?

Answer - 2 : -

The five V’s of Big data is as follows:

  • Volume – Volume represents the volume i.e. amount of data that is growing at a high rate i.e. data volume in Petabytes
  • Velocity – Velocity is the rate at which data grows. Social media contributes a major role in the velocity of growing data.
  • Variety – Variety refers to the different data types i.e. various data formats like text, audios, videos, etc.
  • Veracity – Veracity refers to the uncertainty of available data. Veracity arises due to the high volume of data that brings incompleteness and inconsistency.
  • Value –Value refers to turning data into value. By turning accessed big data into values, businesses may generate revenue.

Question - 3 : - Tell us how big data and Hadoop are related to each other.

Answer - 3 : - Big data and Hadoop are almost synonyms terms. With the rise of big data, Hadoop, a framework that specializes in big data operations also became popular. The framework can be used by professionals to analyze big data and help businesses to make decisions.

Question - 4 : - How is big data analysis helpful in increasing business revenue?

Answer - 4 : - Big data analysis has become very important for the businesses. It helps businesses to differentiate themselves from others and increase the revenue. Through predictive analytics, big data analytics provides businesses customized recommendations and suggestions. Also, big data analytics enables businesses to launch new products depending on customer needs and preferences. These factors make businesses earn more revenue, and thus companies are using big data analytics. Companies may encounter a significant increase of 5-20% in revenue by implementing big data analytics. Some popular companies those are using big data analytics to increase their revenue is – Walmart, LinkedIn, Facebook, Twitter, Bank of America etc.

Question - 5 : - Explain the steps to be followed to deploy a Big Data solution.

Answer - 5 : -

Followings are the three steps that are followed to deploy a Big Data Solution –

i. Data Ingestion

The first step for deploying a big data solution is the data ingestion i.e. extraction of data from various sources. The data source may be a CRM like Salesforce, Enterprise Resource Planning System like SAP, RDBMS like MySQL or any other log files, documents, social media feeds etc. The data can be ingested either through batch jobs or real-time streaming. The extracted data is then stored in HDFS.
ii. Data Storage

After data ingestion, the next step is to store the extracted data. The data either be stored in HDFS or NoSQL database (i.e. HBase). The HDFS storage works well for sequential access whereas HBase for random read/write access.
iii. Data Processing

The final step in deploying a big data solution is the data processing. The data is processed through one of the processing frameworks like Spark, MapReduce, Pig, etc.

Question - 6 : - Why is Hadoop used for Big Data Analytics?

Answer - 6 : -

Since data analysis has become one of the key parameters of business, hence, enterprises are dealing with massive amount of structured, unstructured and semi-structured data. Analyzing unstructured data is quite difficult where Hadoop takes major part with its capabilities of  

  • Storage
  • Processing
  • Data collection
Moreover, Hadoop is open source and runs on commodity hardware. Hence it is a cost-benefit solution for businesses.

Question - 7 : - What is fsck?

Answer - 7 : - fsck stands for File System Check. It is a command used by HDFS. This command is used to check inconsistencies and if there is any problem in the file. For example, if there are any missing blocks for a file, HDFS gets notified through this command.

Question - 8 : - Define respective components of HDFS and YARN

Answer - 8 : -

The two main components of HDFS are-

  • NameNode – This is the master node for processing metadata information for data blocks within the HDFS
  • DataNode/Slave node – This is the node which acts as slave node to store the data, for processing and use by the NameNode
In addition to serving the client requests, the NameNode executes either of two following roles –
  • CheckpointNode – It runs on a different host from the NameNode
  • BackupNode- It is a read-only NameNode which contains file system metadata information excluding the block locations
Hadoop core components
The two main components of YARN are–

  • ResourceManager– This component receives processing requests and accordingly allocates to respective NodeManagers depending on processing needs.
  • NodeManager– It executes tasks on each single Data Node

Question - 9 : - What are the main differences between NAS (Network-attached storage) and HDFS?

Answer - 9 : -

The main differences between NAS (Network-attached storage) and HDFS –

  • HDFS runs on a cluster of machines while NAS runs on an individual machine. Hence, data redundancy is a common issue in HDFS. On the contrary, the replication protocol is different in case of NAS. Thus the chances of data redundancy are much less.
  • Data is stored as data blocks in local drives in case of HDFS. In case of NAS, it is stored in dedicated hardware.

Question - 10 : - What is the Command to format the NameNode?

Answer - 10 : - $ hdfs namenode -format

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