Question

What is private server in COC(clash of clans) ?

Answer 1

You can create your own by following these steps

As a lot of you guys hopefully know. There is such a thing known as "Private" server. It is somewhat complicated to do, for some people. So im gonna give you guys my IP for my server. The steps for android are simple. 
 Android: 
 1: Go to the google play store. 
 2: Download " Host Editor." 
 3: Open it, add a host, 
 4: ip- 192.168.1.107 
 5: Hostname- "Gamea.clashofclans.com" 
 6: Uninstall clash then reinstall. 
 
 iPhone (Jailbreak REQUIRED) 
 1: Go to cydia, download iFile 
 2: (It costs money but if you Have the hack your iphone repo its free) 
 3: Navigate to etc( Click the back button in the top left) 
 4: Change the " Hosts" File 
 5: as Follows "192.168.1.107 game.clashofclans.com 
 6: Uninstall clash then reinstall.

Answer 2

I am pretty sure the don't exist give how super cell operator. this game can only be played on the server's that they provide any site offering a server is as any legitimate as a site of offering cheaper gems it is a complete scam
I even doubt a modded app would be able to run on a server that is not super cells