XK0-006 System Management Practice Question
A system administrator runs the command 'chmod 4755 /usr/local/bin/backup'. What effect does this have on the file?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Sets the SUID bit and gives rwxr-xr-x permissions
The 4 in the first digit sets the SUID bit, so the file runs with the owner's permissions. 755 sets rwxr-xr-x.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Sets the sticky bit and gives rwxr-xr-x permissions
Why it's wrong here
The 4 in 4755 sets the setuid bit, not the sticky bit, and 755 grants owner rwx plus group and others r-x. It is tempting because both are special permission bits set via a leading octal digit, and 1755 would be correct if the sticky bit were actually required.
- ✓
Sets the SUID bit and gives rwxr-xr-x permissions
Why this is correct
The leading 4 sets the SUID bit, so the program runs with the file owner's privileges rather than the invoking user's. The remaining 755 grants rwx to the owner and r-x to group and others, matching the octal digits exactly. This satisfies the stem's requirement to interpret chmod 4755 correctly.
- ✗
Sets the SGID bit and gives rwxr-xr-x permissions
Why it's wrong here
The leading 4 sets SUID, not SGID; SGID requires a leading 2 (2755). The permission digits 755 are correct, but the special bit is wrong. It tempts because SGID on a directory shares group ownership, which is the right choice for collaborative shared directories.
- ✗
Sets the SUID bit and gives rwxrwxr-x permissions
Why it's wrong here
The leading 4 sets SUID, but 755 grants owner rwx and group/other r-x, giving rwsr-xr-x, not rwxrwxr-x. Group and other lack write access. It tempts because 4755 is the classic SUID executable mode, correct when a program must run with the owner's privileges.
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System Backup and Recovery
Key term
chmod
chmod is a command in Linux and Unix-like operating systems used to change the permissions (read, write, execute) of a file or directory.
Key term
SUID
SUID (Set User ID) is a special file permission in Linux that allows a user to run an executable file with the file owner's privileges, typically root, rather than their own.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This XK0-006 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the XK0-006 exam.