A replica set is a group of MongoDB database nodes used for defining database clusters with master-slave replication and automated failover. A replica set contains a single primary node, multiple secondary nodes, and an arbiter node. The primary node receives all write operations while other nodes apply operations from the primary so that all nodes have the same data set.
If your primary node breaks due to hardware failure or system-related issues, the replica set members autonomously select a new primary node, and your application functioning without manual intervention.
In this post, we will explain how to set up a MongoDB replica set with three nodes. We will also show you how to create an environment, configure authentication between multiple database nodes and finally configure the replication between all nodes.