You are the administrator on a Linux network. You have created and are ready to
implement a strong password policy that requires users to change password every thirty
days. Which Linux command could you use to accomplish this task?

A.
Chmod-M30

B.
Chgrp-d30

C.
Chage-M30

D.
Useradd-D30

Explanation:
Chage is change user password expiration policy. The M specified the
maximum number of days the password is valid, and is followed by a number to
indicate those days, here M30 meaning a Maximum of 30 Days. Note, that a
lowercase m indicates the minimum number of days, and a capital M is the
maximum number of days.
Incorrect Answers:
A: chmod is for changing file permissions, not password age.
B: chgrp is for changing group ownership of a file, not password age.
D: useradd or adduser will add user accounts, but does not set password age policy.