Hadoop

What is the primary function of Hadoop MapReduce?

• Data visualization

• Data storage

• Data processing

• Data compression

What is the role of the NameNode in HDFS?

• Stores data

• Executes MapReduce jobs

• Manages the file system namespace and metadata

• Compresses large files

What is the default replication factor in Hadoop Distributed File System (HDFS)?

• 1

• 2

• 3

• 5

What happens in the “shuffle and sort” phase of MapReduce?

• Splits the input files

• Maps keys to nodes

• Moves data from mapper to reducer and sorts by keys

• Stores final output to HDFS

In MapReduce, Reducer receives:

• Key and list of values

• Only values

• Mapped data before shuffle

• Input data directly from HDFS

What is the output format of the map function in MapReduce?

• Key-value pairs

• Text stream
  

• Binary data

• JSON objects

Hadoop is best suited for:

• Online transaction processing

• Structured databases only

• Large-scale batch processing of unstructured/semi-structured data

• Small data sets

Which of the following are core components of Hadoop?

• HDFS, MapReduce, YARN

• Hive, Pig, Mahout

• Spark, Flink, Storm

• Sqoop, Flume, Kafka

What is the main responsibility of the NameNode in HDFS?

• Stores the data

• Processes MapReduce tasks

• Maintains file system metadata

• Acts as a backup node

In Hadoop, which node actually stores the data blocks?

• NameNode

• ResourceManager

• DataNode

• TaskTracker