This post is describing how to setup a Mongo Db database in a clustering mode. I choose to deploy 3 replica set on 3 different bare metal server running centos 7 and to add 1 arbiter to reduce vote problem during a server crash or reboot.
You will find the different steps to make this configuration running, the way to secure it in a vlan and to activate the authentication.
I also added some elements on the way to backup it. Feel free to propose enhancement and links in the comments.