You try to switch to user john using su john but get the error: Authentication failure. What is the most likely cause?

medium📝 Debug Q14 of 15

Linux CLI - Users and Groups

You try to switch to user john using su john but get the error: Authentication failure. What is the most likely cause?

AYou entered the wrong password for john

BUser john does not exist

CYou forgot to use sudo before su

DYou need to be root to use su

Step-by-Step Solution

Solution:

Step 1: Understand the error message
Authentication failure means the password entered was incorrect for the target user.
Step 2: Analyze other options
User existence error would say 'unknown user'. Using sudo is not required for su. You do not need to be root to switch users if you know the password.
Final Answer:
You entered the wrong password for john -> Option A
Quick Check:
Authentication failure = wrong password [OK]

Quick Trick: Authentication failure means wrong password [OK]

Common Mistakes:

Master "Users and Groups" in Linux CLI

9 interactive learning modes - each teaches the same concept differently

Want More Practice?

15+ quiz questions · All difficulty levels · Free

More Linux CLI Quizzes