Which among the following is the duties of the Data Nodes

manage file system namespace
stores meta-data
regulates client's access to files
perform read-write operation as per request for the clients

The correct answer is: D. perform read-write operation as per request for the clients.

Data nodes are the workhorses of a Hadoop cluster. They store the actual data, and they are responsible for performing read and write operations on that data. Data nodes are also responsible for replicating data to other nodes in the cluster, which helps to ensure that the data is always available.

Option A is incorrect because the file system namespace is managed by the NameNode.

Option B is incorrect because metadata is stored by the NameNode.

Option C is incorrect because client access to files is regulated by the NameNode.