title: Sudo su don't ask Password to switch from Sudo user to Root User
body: <p>In my linux system i have two sudo users and another root. When i want to switch from sudo user to Root user, and put command SU to switch to root then system ask for Root user password.But when i enter same command with SUDO, like sudo su then my user switches to Root user and don't ask for Root user Password.</p>
  
  <p>Tested on Ubuntu and Fedora, same behavior on both platform.</p>