Whenever I issue command sudo apt-get install ** it does not ask for password, not in my admin user too.

How to make it prompt for password?

My sudoer :

ubuntu:~$ sudo cat /etc/sudoers

#

# This file MUST be edited with the 'visudo' command as root.

#

# Please consider adding local content in /etc/sudoers.d/ instead of

# directly modifying this file.

#

# See the man page for details on how to write a sudoers file.

#

Defaults    env_reset

Defaults    secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"



# Host alias specification



# User alias specification



# Cmnd alias specification



# User privilege specification

root    ALL=(ALL:ALL) ALL



# Members of the admin group may gain root privileges

%admin ALL=(ALL) ALL



# Allow members of group sudo to execute any command

%sudo   ALL=(ALL:ALL) ALL



# See sudoers(5) for more information on "#include" directives:



#includedir /etc/sudoers.d

ALL ALL=(ALL) NOPASSWD:ALL