XK0-006 Practice Test 27 — 15 Questions

Question 1

An administrator is troubleshooting a server that fails to boot. The system displays 'kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0).' Which of the following is the most likely cause?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Incorrect root= parameter in the kernel command line. The error 'VFS: Unable to mount root fs on unknown-block(0,0)' indicates the kernel cannot locate the root filesystem. The 'unknown-block(0,0)' value means the kernel received no valid device number for the root partition, which is almost always caused by an incorrect or missing 'root=' parameter in the kernel command line (e.g., in GRUB). This prevents the kernel from finding the correct block device to mount as '/'.

Answer

The init binary is missing

Answer

The hard drive has a hardware failure

Answer

The kernel image is corrupted

Answer

The Master Boot Record is damaged

Question 2

Drag and drop the steps to configure a static IP address using the command line in the correct order.

Accepted Answer

Edit the network configuration file, configure the static IP address, save the file, restart the network service.. Static IP configuration involves editing the network config file and restarting the service to apply changes.

Answer

Restart the network service, edit the network configuration file, configure the static IP address, save the file.

Answer

Edit the network configuration file, save the file, configure the static IP address, restart the network service.

Answer

Configure the static IP address, restart the network service, edit the network configuration file, save the file.

Question 3

Drag and drop the steps to create a new LVM logical volume in the correct order.

Accepted Answer

Create physical volumes, then create volume group, then create logical volume, then format the logical volume, then mount the logical volume.. LVM requires physical volumes, a volume group, and then a logical volume before formatting and mounting.

Answer

Create volume group, then create physical volumes, then create logical volume, then format the logical volume, then mount the logical volume.

Answer

Create physical volumes, then create volume group, then format the logical volume, then create logical volume, then mount the logical volume.

Answer

Create physical volumes, then create logical volume, then create volume group, then format the logical volume, then mount the logical volume.

Question 4

Match each Linux command to its primary function.

Accepted Answer

df: Display disk space usage. The correct matches are: df shows disk space, du estimates file space, fdisk manages partitions, mkfs creates filesystems. Common confusions involve mixing df/du and mount/fsck with wrong functions.

Answer

mount: Estimate file space usage

Answer

fsck: Display disk space usage

Question 5

A Linux server runs a critical service managed by a systemd service unit. The administrator needs to configure the service to automatically restart if it crashes, but only up to 3 times within a 30-second window. If the service restarts more than 3 times in 30 seconds, systemd should stop attempting to restart and leave the service in a failed state. Which set of directives should be added to the [Service] section of the unit file to achieve this behavior?

Accepted Answer

`Restart=on-failure` and `StartLimitBurst=3` and `StartLimitIntervalSec=30`. It uses `Restart=on-failure` to trigger a restart only when the service crashes (not on other stops), combined with `StartLimitBurst=3` and `StartLimitIntervalSec=30` to limit restarts to 3 attempts within a 30-second window. When the burst limit is exceeded, systemd automatically places the unit in a failed state, exactly matching the requirement.

Answer

`Restart=on-abort` and `MaxStartups=3`

Answer

`Restart=on-failure` and `StartLimitBurst=5` and `StartLimitIntervalSec=60`

Answer

`Restart=always` and `RestartSec=10`

Question 6

A senior administrator is troubleshooting a shell script that fails to execute properly. The script starts with #!/bin/bash and has execute permissions. Which of the following could cause the script to fail to run when invoked as ./script.sh?

Accepted Answer

The script contains carriage return characters (\r).. Carriage return characters (\r) are a common issue when scripts are edited on Windows and then transferred to Linux. The shebang line #!/bin/bash expects a Unix-style line ending (LF), but \r characters cause the shell to interpret the command interpreter as '/bin/bash\r', which is not a valid executable path. This results in a 'No such file or directory' error when the script is invoked as ./script.sh, even though permissions are correct.

Answer

The shebang line is not on the first line.

Answer

The script uses #!/bin/sh instead of bash.

Answer

The script starts with a byte order mark (BOM).

Question 7

A system administrator notices that a Linux server is running low on disk space. Which command should be used to identify which directories are consuming the most space?

Accepted Answer

du -h /path | sort -rh. The `du -h /path | sort -rh` command recursively calculates disk usage for each directory under the specified path, displays sizes in human-readable format (`-h`), and then sorts the output in reverse numerical order (`-rh`), showing the largest directories first. This directly identifies which directories are consuming the most space, which is exactly what the system administrator needs.

Answer

ls -laR

Answer

find / -size +100M

Answer

df -h

Question 8

Which THREE of the following are valid methods to troubleshoot a service that fails to start?

Accepted Answer

Run the service executable manually from the command line to see error output.. Running the service executable manually from the command line often reveals stderr output, error codes, or missing configuration details that are suppressed when the service is started by systemd. This direct execution bypasses the service manager's logging and can show immediate, unfiltered error messages that help pinpoint the failure reason.

Answer

Run df -h to check disk space.

Answer

Reload the systemd daemon with systemctl daemon-reload.

Question 9

An administrator needs to update the system time using an NTP server immediately without waiting for the next scheduled sync. Which command should be used?

Accepted Answer

ntpdate pool.ntp.org. The `ntpdate` command is used to immediately synchronize the system clock with an NTP server, bypassing the daemon-based scheduled sync. Option D runs `ntpdate pool.ntp.org`, which performs a one-time query and sets the time instantly, making it the correct choice for an immediate update.

Answer

timedatectl set-ntp true

Answer

systemctl start ntpd

Answer

ntpq -p

Question 10

A DevOps engineer needs to automate the deployment of a microservice using Ansible. The playbook should install the latest version of nginx on all web servers. Which Ansible module should be used in the playbook?

Accepted Answer

apt: name=nginx state=latest. The `apt` module is the proper Ansible module for managing packages on Debian-based systems, and `state=latest` ensures the most recent version of nginx is installed. This aligns with the requirement to automate deployment using Ansible's declarative package management rather than imperative shell commands.

Answer

service: name=nginx state=started

Answer

command: apt install nginx

Answer

yum: name=nginx state=latest

Question 11

A system administrator notices that a server's disk space is critically low. Which command should be used to identify the largest files or directories consuming space?

Accepted Answer

du -sh /*. `du -sh /*` recursively calculates disk usage for each top-level directory and file under root, summarizing sizes in human-readable format. This directly identifies the largest space consumers, which is the stated goal. The `-s` flag provides a total per argument, and `/*` targets all immediate children of `/`.

Answer

ls -la /

Answer

fdisk -l

Answer

df -h

Question 12

A user cannot access a file. The file has permissions 640 and is owned by root:root. The user is not root and not in the root group. Which command should the administrator use to allow the user to read the file?

Accepted Answer

chmod o+r file. The file has permissions 640, which means the owner (root) has read/write, the group (root) has read, and others have no permissions. Since the user is not root and not in the root group, they fall into the 'others' category. The command `chmod o+r file` adds read permission for others, allowing the user to read the file without changing ownership or group membership.

Answer

chgrp user file

Answer

setfacl -m u:user:r file

Answer

chown user file

Question 13

A security-conscious administrator runs containers with Podman. Which THREE methods ensure that a container runs with the least privilege required?

Accepted Answer

--user 1000. Using `--user 1000` runs the container process with a non-root user (UID 1000), which reduces the attack surface by preventing root-level access inside the container. This is a fundamental least-privilege practice, as containers default to running as root unless explicitly changed.

Answer

--privileged

Answer

--read-only=true

Question 14

An administrator needs to ensure that a custom script /usr/local/bin/backup.sh runs every day at 2:00 AM and logs output to /var/log/backup.log. How should this be configured using systemd?

Accepted Answer

Create a systemd timer unit that activates a service unit, with OnCalendar=daily and the desired time.. Systemd timer units are the modern, recommended method for scheduling recurring tasks on Linux systems that use systemd. By creating a timer unit with `OnCalendar=daily` and specifying the desired time (e.g., `02:00:00`), the associated service unit will execute `/usr/local/bin/backup.sh` at 2:00 AM daily. The service unit can also redirect output to `/var/log/backup.log` using standard output/error directives, ensuring logging is handled natively within the systemd framework.

Answer

Use anacron with a delay of 0 and a period of 1 day.

Answer

Add a cron job with '0 2 * * * /usr/local/bin/backup.sh >> /var/log/backup.log 2>&1'.

Answer

Place the script in /etc/cron.daily/ and set the time with the 'START_HOURS_RANGE' variable.

Question 15

A company uses a Linux server running a web application. Users report that they cannot access the website. The administrator checks the web server status and finds it is not running. Which command should the administrator use to view the reason for the service failure?

Accepted Answer

journalctl -xe. The `journalctl -xe` command displays the systemd journal log with the `-x` flag adding explanatory context and `-e` jumping to the end of the log, which is the most direct way to view the reason a systemd-managed service like httpd failed. Since the web server is managed by systemd, its failure reason (e.g., exit code, segfault, configuration error) is recorded in the journal, and this command retrieves that specific failure detail without requiring manual log file parsing.

Answer

systemctl status httpd --full

Answer

tail -f /var/log/httpd/access_log

Answer

dmesg | grep httpd