Hadoop may be used in three different ways:
Standalone mode: Hadoop’s default mode performs input and output operations using the local file system. This mode is primarily intended for debugging and does not support the use of HDFS. In addition, the mapred-site.xml, core-site.xml, and hdfs-site.xml files do not require any specific setup in this mode. When compared to other settings, this one operates significantly faster.
Pseudo-distributed mode (Single-node Cluster): You’ll need settings for all three files listed above in this scenario. All daemons are operating on one node in this example, thus both the Master and Slave nodes are the same.
Fully distributed mode (Multi-node Cluster): This is the Hadoop (what Hadoop is known for) production phase, where data is consumed and spread across several nodes on a Hadoop cluster. Master and Slave nodes are assigned separately.