We already have a setup of Win2012 R2 Servers but as soon as we promoting a new Win Server 2012 R2 as a New Child Domain in existing Forest (i.e.xyz.abc.com), The Promotion completed successfully but after that It Start rebooting in 15mins.
We tried to install all windows updates/Hotfixes but no solution.
But Once we demote it it starts working fine again.
It seems a bug in Windows Server 2012 R2.