You attempt to switch to user guest using su guest but receive "Authentication failure". What is the most probable reason?

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Linux CLI - Users and Groups

You attempt to switch to user guest using su guest but receive "Authentication failure". What is the most probable reason?

AThe <code>guest</code> user account is locked or has no password set

BYou forgot to use the <code>-</code> option for a login shell

CThe <code>guest</code> user does not exist in /etc/passwd

DYou need to run <code>su</code> as root to switch users

Step-by-Step Solution

Solution:

Step 1: Understand authentication failure causes
An authentication failure usually means the password entered is incorrect or the account is locked.
Step 2: Analyze options
guest user likely exists but may be locked or have no password set, causing failure.
You forgot to use the - option for a login shell is unrelated to authentication failure.
The guest user does not exist in /etc/passwd would cause "user does not exist" error, not authentication failure.
You need to run su as root to switch users is incorrect; any user can run su but must know the target user's password.
Final Answer:
The guest user account is locked or has no password set -> Option A
Quick Check:
Authentication failure often means locked or no password [OK]

Quick Trick: Authentication failure usually means wrong or no password [OK]

Common Mistakes:

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