What is NameNode in Hadoop?

Question

What is stored in the NameNode?

Answer 1

There are primarily two nodes in the master-slave architecture followed by hadoop clusters, NameNode and DataNode. The NameNode stores something called 'metadata' and the DataNode contains the actual data. 

Metadata simply means 'data about the data'. In the Hadoop context, this means that the NameNode contains where and which data node of the cluster contains what and which chunk of a file. Basically, file location information. It is also the node on which the job tracker runs. 

Learn more about concepts like NameNode and DataNode to master Hadoop by taking up Hadoop Online Training.