I have a SharePoint farm with Three Servers. First server role is "Application with Search", Second is "Front-end with Distributed Cache", Third is database server. I want to know is it possible to configure Network Load Balancer with the current servers in the Farm?
Not in that role configuration that I can see. I think what you need is two of the same and you load balance each. 2 WFE w/Distributed Cache, 2 App Servers and 2 Database Servers. However, the Database servers wouldn't exactly be using Network Load Balancing but instead SQL High Availability where you configure an SQL Availability Group Listener.