XK0-006 Practice Exam 2 — 20 Questions

Question 1

A systems administrator needs to ensure that a custom service runs with a specific priority on a Linux server. Which command should the administrator use to achieve this?

Accepted Answer

nice -n -10 /usr/local/bin/myservice. The `nice` command adjusts the CPU scheduling priority of a process at launch time. Using `nice -n -10` sets a higher priority (lower nice value) for the new service, ensuring it runs with the specified priority from the start. This directly meets the requirement to run a custom service with a specific priority.

Answer

renice -10 -p 1234

Answer

ionice -c 2 -n 0 -p 1234

Answer

chrt -r 99 /usr/local/bin/myservice

Question 2

A Linux engineer is investigating high disk I/O on a server. Which command provides disk I/O statistics including %util, await, r/s, and w/s?

Accepted Answer

iostat -x 1. iostat reports CPU and disk I/O statistics, with columns like %util, await, r/s, and w/s.

Answer

sar -b

Answer

vmstat 1 5

Answer

free -h

Question 3

A security engineer needs to verify the authenticity of a downloaded file using its detached GPG signature (file.sig). Which command should be used?

Accepted Answer

gpg --verify file.sig. The `gpg --verify file.sig` command is used to verify the authenticity of a file using its detached GPG signature. The detached signature file (file.sig) contains the cryptographic signature, and GPG checks it against the original file (which must be present in the same directory with the same base name) using the signer's public key from the local keyring. This confirms that the file was signed by the holder of the corresponding private key and has not been tampered with.

Answer

gpg --sign file

Answer

gpg --list-keys

Answer

gpg --decrypt file.gpg

Question 4

Which TWO tools are specifically designed to detect rootkits on a Linux system?

Accepted Answer

rkhunter. rkhunter (B) is a dedicated rootkit hunter that scans for known rootkit signatures, suspicious files, and hidden processes on Linux, making it specifically designed for rootkit detection. chkrootkit (E) is likewise a purpose-built tool that checks system binaries and common rootkit infection vectors on Linux. By contrast, lsof (A) only lists open files and associated processes, netstat (C) merely displays network connections and routing tables, and clamav (D) is an antivirus scanner targeting malware such as viruses and trojans rather than rootkits specifically, so none of these are specifically designed for rootkit detection.

Answer

lsof

Answer

netstat

Answer

clamav

Question 5

A user wants to create a symbolic link to a file named 'original' in their home directory. Which command creates a symbolic link named 'link'?

Accepted Answer

ln -s original link. The 'ln -s' command creates a symbolic (soft) link. The syntax is 'ln -s ', so 'ln -s original link' creates a symlink named 'link' that points to 'original'. Without the -s flag, ln creates a hard link instead.

Answer

ln original link

Answer

ln -s link original

Answer

symlink original link

Question 6

An administrator wants to force a password change for user 'alice' on next login. Which command is appropriate?

Accepted Answer

passwd --expire alice. The `passwd --expire alice` command (equivalent to `passwd -e alice`) immediately expires alice's password by setting the shadow file's last-change date to 0, forcing a password change at her next login. This is the standard Linux mechanism for administrators to force a one-time password reset without disabling the account.

Answer

passwd -l alice

Answer

chage -l alice

Answer

usermod -f alice

Question 7

An administrator is troubleshooting a web server that is running under SELinux enforcing mode. The web content is located in a non-standard directory /webfiles. Using the standard SELinux context 'httpd_sys_content_t', the files are still inaccessible. Which command will properly set the context recursively and persist across relabels?

Accepted Answer

semanage fcontext -a -t httpd_sys_content_t '/webfiles(/.*)?' ; restorecon -Rv /webfiles. `semanage fcontext -a -t httpd_sys_content_t '/webfiles(/.*)?'` adds a file-context mapping to the SELinux policy database, ensuring the context survives a `restorecon` or filesystem relabel. The subsequent `restorecon -Rv /webfiles` applies that context recursively to the directory. Without the `semanage` entry, `restorecon` alone would revert to the default context (often `default_t`), which is not accessible by httpd.

Answer

chcon -R -t httpd_sys_content_t /webfiles

Answer

setenforce 0

Answer

restorecon -Rv /webfiles

Question 8

An administrator needs to add a script to be executed daily. The script is placed at /etc/cron.daily/myscript. After placing the script, it does not run. Based on the exhibit, what is the most likely issue?

Accepted Answer

The script is not executable. Scripts placed in /etc/cron.daily/ are executed by run-parts, which requires files to have the executable bit set. Without the execute permission (e.g., chmod +x), the script is skipped entirely, even if it is owned correctly and the cron daemon is active.

Answer

The script is owned by the wrong user

Answer

The cron daemon is not running

Answer

The script is not listed in /etc/crontab

Answer

Anacron is not installed

Question 9

Which TWO of the following are valid methods for debugging a Bash script? (Choose TWO.)

Accepted Answer

Run the script with 'bash -x script.sh'. Running 'bash -x script.sh' enables an execution trace that prints each command and its arguments to stderr before executing it, which is a standard debugging method for Bash scripts. Option C is correct because adding 'set -x' at the start of the script achieves the same trace output, but from within the script itself, allowing granular control over which sections are traced.

Answer

Add 'set -r' to restrict shell

Answer

Run the script with 'bash -d script.sh'

Answer

Add 'set -n' to check syntax

Question 10

A system administrator wants to schedule a script to run every Monday at 3 AM. Which cron entry is correct?

Accepted Answer

0 3 * * 1 /path/to/script.sh. The cron syntax for 'at 3 AM every Monday' is minute 0, hour 3, day-of-month *, month *, and day-of-week 1 (where 0 and 7 both represent Sunday, and 1 represents Monday). This matches the required schedule exactly.

Answer

0 3 1 * * /path/to/script.sh

Answer

3 0 * * 1 /path/to/script.sh

Answer

0 3 * * 2 /path/to/script.sh

Question 11

A user reports that a custom application service fails to start with a 'Permission denied' error in the logs. The service runs under the 'appuser' account. Which is the most likely cause and the first step to diagnose?

Accepted Answer

SELinux is blocking the service; check journalctl for AVC denials and use restorecon or setsebool.. SELinux enforces mandatory access controls that can block a service from starting even when standard Linux file permissions are correct. The 'Permission denied' error, combined with the service running under a non-root user, strongly suggests SELinux is denying access. Checking journalctl for AVC denials is the standard first diagnostic step to confirm SELinux involvement, followed by using restorecon to fix file context labels or setsebool to adjust SELinux booleans.

Answer

The root password is incorrect; change root password with passwd.

Answer

The service binary does not have execute permission for appuser; use chmod +x.

Answer

The systemd target is not set to multi-user; run systemctl set-default multi-user.target.

Question 12

What does the `set -x` command do when placed at the top of a bash script?

Accepted Answer

Displays each command before executing it. `set -x` enables a shell debugging mode that prints each command (after expansion) to stderr before executing it. This is commonly used in bash scripts to trace execution flow and debug complex logic.

Answer

Enables position parameters

Answer

Exits the script on error

Answer

Treats unset variables as errors

Question 13

A technician needs to check the kernel ring buffer for hardware errors detected during system boot. Which command should be used?

Accepted Answer

dmesg. The kernel ring buffer contains messages emitted by the kernel, including hardware detection and error messages during boot. The 'dmesg' command reads and prints this buffer directly. It is the canonical tool for inspecting kernel-level hardware errors, driver initialization failures, and boot-time device detection.

Answer

journalctl -k

Answer

lspci

Answer

cat /var/log/boot.log

Question 14

A system administrator wants to deploy a containerized application on a Linux server with minimal overhead and without a daemon. Which container runtime should be used?

Accepted Answer

Podman. Podman is the correct choice because it is a daemonless container engine that runs containers directly under the user's process space, using a fork-exec model rather than a background daemon. This aligns with the requirement for minimal overhead and no daemon, as Podman does not require a persistent service to manage containers.

Answer

containerd

Answer

LXC

Answer

Docker

Question 15

Match each Linux filesystem to its typical use case.

Accepted Answer

ext4: General-purpose filesystem for Linux desktops and servers. Correct matches: ext4 for general use, XFS for large files, Btrfs for advanced features. Common confusions: swap vs tmpfs where swap is disk-based virtual memory and tmpfs is RAM-based temporary storage.

Answer

swap: Temporary filesystem stored in RAM

Answer

tmpfs: Space on disk used as virtual memory

Question 16

A Linux administrator needs to verify which network interfaces are up and their IP addresses on a server. Which command provides this information?

Accepted Answer

ip addr. The `ip addr` command displays all network interfaces along with their IP addresses, MAC addresses, and status (UP/DOWN).

Answer

ss -tlnp

Answer

nmcli dev show

Answer

ifconfig -a

Question 17

A security audit reveals that the /etc/shadow file has permissions 0644 and is owned by root:shadow. The auditor states that this is a security risk because any local user can read password hashes. The administrator wants to fix the permissions to ensure that only root and the shadow group can read the file, and no one else can read it. Additionally, the administrator wants to set the immutable attribute on the file to prevent accidental modification. Which set of commands achieves the desired state?

Accepted Answer

chmod 640 /etc/shadow; chattr +i /etc/shadow. Chmod 640 sets the file permissions to read/write for root (owner) and read-only for the shadow group, while removing all access for others. chattr +i sets the immutable attribute, which prevents any modifications (including deletion, renaming, or content changes) even by root until the attribute is removed. This satisfies the requirement that only root and the shadow group can read the file, and no one else can read it, while also protecting against accidental modification.

Answer

chmod 640 /etc/shadow; chattr +a /etc/shadow

Answer

chmod 640 /etc/shadow; chmod +i /etc/shadow

Answer

chmod 600 /etc/shadow; chattr +i /etc/shadow

Question 18

Which command is used to query the status of a service managed by systemd?

Accepted Answer

systemctl status servicename. systemctl status shows whether a service is active, enabled, and recent log entries.

Answer

journalctl -u servicename

Answer

service servicename status

Answer

systemctl list-units --type=service

Question 19

Which TWO commands can be used to change the group ownership of a file? (Choose exactly two.)

Accepted Answer

chgrp. Option B (chgrp) is correct because chgrp is the dedicated command for changing a file's group ownership, e.g. 'chgrp developers file.txt' sets the group of file.txt to developers. Option D (chown) is correct because chown can also change group ownership using the ':group' or '.group' syntax, e.g. 'chown :developers file.txt' or 'chown user:developers file.txt'. Option A (chmod) is incorrect because it modifies read/write/execute permission bits (and special bits like setgid), not the owning group itself. Option C (groupmod) is incorrect because it modifies attributes of an existing group in /etc/group, such as its name or GID, not a file's group ownership. Option E (usermod) is incorrect because it modifies user account attributes such as group membership, home directory, or shell, not file ownership.

Answer

chmod

Answer

groupmod

Answer

usermod

Question 20

A Linux system has a directory with permissions drwxr-xr-x. A user in the group 'dev' tries to create a new file inside this directory. Which permission is missing that prevents the user from creating the file?

Accepted Answer

Write permission for the group. The directory has write permission for the owner, but only read and execute for the group. To create a file, the user needs write permission on the directory, which is not granted to the group.

Answer

Write permission for the owner

Answer

Sticky bit is set

Answer

Execute permission for the group