What is Hadoop

Apache Hadoop is an open source to load and process the big data efficiently.

Hadoop Distributed Vendors

Cloudera, Hortonworks, MapR etc.

What are major component of Hadoop

There are two major component of Hadoop. One is HDFS to store your data and Map Reduce to process your data.

Which command we use to load data from local to hdfs

copyFromLocal, put and moveFromLocal.

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Which command we use to load data from hdfs to local.

copyToLocal and get command.

Which command we used to list HDFS

Hadoop fs –ls.

Which command we used to create directory in HDFS

Hadoop fs –mkdir dir_name

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What is number of default replication of data in distributed mode

Default replication is 3 in distributed mode.

What is the default partitioner in Hadoop

Hash partitioner

What is combiner in Hadoop

Combiner is also known as mini reducer for map reduce program. It is used to enhance the performance. Combiner processes the large output of mapper and filters and summarizes it and then passes it to reducer for efficient and fast process.