I have SharePoint 2013 server. And the customer required to have two servers inside the same farm. So in case one server went down to have the other server working. So how I can configure such a scenario within SharePoint 2013 Farm.
The quickest way is to join the second server to farm and create NLB (software or hardware) using both of them.
Software NLB can be created e.g. using Windows Server Network Load balancing, hardware NLB - using some devices like Cisco GSS.
Those links may help: