XK0-006 Practice Exam 58 — 20 Questions

Question 1

An Ansible playbook fails with a syntax error. Which command validates the playbook syntax without running it?

Accepted Answer

ansible-playbook --syntax-check. The `--syntax-check` flag is a built-in option of `ansible-playbook` that parses the YAML file and validates its syntax without executing any tasks. This is the correct tool for catching syntax errors in a playbook before running it.

Answer

ansible-lint playbook.yml

Answer

ansible-playbook --check

Answer

ansible-playbook --validate

Question 2

Refer to the exhibit. An administrator wants to optimize a server running a high-throughput database application. Which command should be used to apply the recommended profile?

Accepted Answer

sudo tuned-adm profile throughput-performance. The tuned-adm recommend command suggests 'throughput-performance', which is suitable for database workloads. The correct command to apply it is 'tuned-adm profile throughput-performance'.

Answer

sudo tuned-adm profile balanced

Answer

sudo tuned-adm off

Answer

sudo systemctl set-default tuned

Question 3

An administrator is tasked with creating a systemd service that runs a Python script after the network is available. The script must restart automatically if it fails. Which systemd service unit directive should be used to ensure restart on failure?

Accepted Answer

Restart=on-failure. The `Restart=on-failure` directive instructs systemd to restart the service unit only when the process exits with a non-zero exit code, is terminated by a signal (including SIGKILL), or times out. This is the correct choice because the requirement is to restart the script only if it fails, not unconditionally. Using `Restart=always` would restart the service even after a clean exit, which is unnecessary and could mask intentional stops.

Answer

Restart=always

Answer

RemainAfterExit=yes

Answer

RestartSec=5

Question 4

An administrator needs to ensure that only users from the 'ops' group can SSH into a server. Which configuration in /etc/ssh/sshd_config accomplishes this?

Accepted Answer

AllowGroups ops. The `AllowGroups` directive in `/etc/ssh/sshd_config` restricts SSH access to only users who are members of the specified group. By setting `AllowGroups ops`, only users belonging to the 'ops' group will be permitted to log in via SSH, which directly meets the requirement.

Answer

Match Group ops DenyUsers *

Answer

AllowUsers ops

Answer

DenyUsers all

Question 5

An administrator is configuring sudo access for a group of developers. They should be able to run any command as root, but only after authenticating with their own password. Which TWO configuration lines in /etc/sudoers would achieve this? (Select TWO.)

Accepted Answer

%developers ALL=(ALL) ALL. The syntax `%developers ALL=(ALL) ALL` grants members of the `developers` group permission to run any command as any user (including root) on any host, and by default sudo requires the user's own password for authentication. Option E is also correct because `PASSWD: ALL` explicitly enforces password authentication for all commands, overriding any global `!authenticate` or `NOPASSWD` settings. Together, these two lines ensure the developers must authenticate with their own password before executing commands as root.

Answer

Defaults:%developers !authenticate

Answer

root ALL=(ALL) ALL

Answer

%developers ALL=(ALL) NOPASSWD: ALL

Question 6

A system administrator is writing an Ansible playbook to manage a web server. Which three of the following are valid Ansible modules for system administration? (Choose THREE.)

Accepted Answer

service. apt, service, and copy are standard Ansible modules for package management, service control, and file copying.

Answer

useradd

Answer

chmod

Question 7

A developer is writing a shell script that needs to handle errors. Which THREE of the following are best practices for robust script error handling?

Accepted Answer

Check the exit code of commands using $?. Checking the exit code of commands using `$?` allows the script to conditionally handle failures based on the specific return value of each command. This is a fundamental error-handling technique in shell scripting, as every command returns an exit code (0 for success, non-zero for failure), and inspecting `$?` immediately after a command lets the developer decide how to respond to that specific error.

Answer

Ignore errors to simplify the script

Answer

Use set +e to allow the script to continue on error

Question 8

You are a Linux system administrator for a small company. You have written a BASH script that checks disk usage and sends an email alert if any partition exceeds 90% usage. The script works when run manually but does not produce alerts when run via cron. Which of the following is the most likely cause?

Accepted Answer

The cron job's PATH variable does not include the directory where the mail command is located. When a script runs manually, it inherits the user's interactive shell environment, including the PATH variable that typically includes directories like /usr/bin and /usr/local/bin where the mail command resides. However, cron jobs execute in a minimal environment with a very restricted PATH (often just /usr/bin:/bin). If the mail command is located in a directory not in cron's default PATH, such as /usr/sbin or /opt/bin, the script will fail silently when attempting to send the email, even though the disk usage check itself succeeds. This is the most common cause of scripts working manually but failing under cron.

Answer

The script has incorrect file permissions

Answer

The cron scheduler is disabled

Answer

The script uses relative paths to check partitions

Question 9

Refer to the exhibit. A Linux administrator runs the netstat command to check listening services. The output shows that services are listening on ports 22, 80, and 443. Which of the following conclusions is correct based on the exhibit?

Accepted Answer

The Apache HTTP server is running and listening on both port 80 and port 443. The netstat output shows services listening on ports 80 and 443, which are the standard ports for HTTP and HTTPS respectively. Apache HTTP server is the most common service that listens on both these ports simultaneously. The fact that both ports are listed as listening indicates that Apache (or another web server) is bound to these ports and ready to accept connections.

Answer

The HTTP server is only listening on the loopback interface

Answer

A firewall is blocking incoming connections to port 443

Answer

The SSH daemon is configured to listen on a non-standard port

Question 10

Which TWO of the following are best practices for securing the GRUB boot loader?

Accepted Answer

Encrypt the boot partition.. Setting a GRUB password (option C) prevents unauthorized users from editing boot parameters or booting into single-user mode, which could otherwise bypass system authentication. Encrypting the boot partition (option B) protects the integrity and confidentiality of the kernel and initramfs, ensuring that tampered or malicious code cannot be loaded during boot. Both measures are recommended in security baselines to enforce boot‑level access control.

Answer

Enable Secure Boot.

Answer

Set the boot timeout to 0.

Answer

Disable USB boot.

Question 11

Refer to the exhibit. A remote user is unable to SSH to the server. Based on the journalctl output, what is the most likely cause?

Accepted Answer

The user is entering the wrong password. The journalctl output shows 'Failed password for user' followed by 'Connection closed by authenticating user', which indicates that the SSH authentication process was attempted but failed due to an incorrect password. This log entry is generated by the SSH daemon (sshd) when a password authentication attempt fails, and the connection is subsequently closed. No other errors (e.g., connection refused, timeout, or denied by hosts.deny) are present, making incorrect password the most likely cause.

Answer

The SSH service is not running

Answer

The user's IP address is in the hosts.deny file

Answer

The SSH port is blocked by a firewall

Question 12

A system administrator needs to ensure that only specific users can execute the 'sudo' command. Which configuration file should be modified?

Accepted Answer

/etc/sudoers. The /etc/sudoers file controls which users and groups can execute commands with elevated privileges via the sudo utility. It uses a specific syntax to define user privileges, such as 'username ALL=(ALL) ALL', and must be edited with the visudo command to prevent syntax errors that could lock out administrative access. Modifying this file is the standard method for granting or restricting sudo access on Linux systems.

Answer

/etc/shadow

Answer

/etc/passwd

Answer

/etc/group

Question 13

A developer runs a web application inside a Podman container. The application logs HTTP requests to stdout in JSON format. The operations team wants to centralize these logs by forwarding them to a remote syslog server. The administrator considers several approaches. Which approach is the most reliable and recommended way to forward container logs to syslog without modifying the application?

Accepted Answer

Use `journalctl -u container-name` to export logs via a syslog forwarder.. Using journalctl to export logs via a syslog forwarder is the most reliable and recommended approach because it leverages the container runtime's logging mechanism without modifying the application. By default, Podman sends container logs to the systemd journal, which can be configured to forward logs to a remote syslog server using journald's built-in forwarding capabilities (e.g., setting ForwardToSyslog=yes in /etc/systemd/journald.conf). This method is persistent, reliable, and does not require changes to the application or its configuration.

Answer

Use a cron job to run `podman logs -f` and pipe the output to `logger`.

Answer

Use `podman exec` to run a log shipper inside the container.

Answer

Configure the application to write logs to a file in a mounted volume, and have the host's syslog daemon tail that file.

Question 14

Which TWO commands can be used to display the amount of free and used memory on a Linux system?

Accepted Answer

free -h. The `free -h` command displays the total, used, and free physical memory (RAM) and swap space in a human-readable format. The `cat /proc/meminfo` command reads the kernel's memory statistics directly from the virtual filesystem, providing detailed information about memory usage, including free, available, buffered, and cached memory. Both commands are standard tools for inspecting memory utilization on a Linux system.

Answer

df -h

Answer

du -sh

Answer

iostat

Question 15

Which THREE tools are commonly used for configuration management?

Accepted Answer

Chef. Chef is a configuration management tool that uses a Ruby-based DSL to define system configurations as 'recipes' and 'cookbooks'. It follows a pull-based model where nodes run the Chef client to fetch and apply configurations from a Chef server, ensuring desired state compliance across infrastructure.

Answer

Kubernetes

Answer

Docker

Question 16

The script in the exhibit runs successfully but the administrator expects it to indicate success. What change should be made?

Accepted Answer

Change 'exit 1' to 'exit 0'. The script uses 'exit 1' to terminate, which indicates a failure or error condition to the shell. The administrator expects the script to indicate success, so the exit code must be changed to 'exit 0', which is the standard Unix/Linux convention for successful execution. Exit codes are how scripts communicate their status to the calling process, and only exit 0 means success.

Answer

Replace $system_info with just system_info

Answer

Change the variable name to SYSTEM_INFO

Answer

Change 'exit 1' to 'exit 0' and remove the quotes around $system_info

Question 17

A company runs a critical web application on a Linux server. The server has 16GB RAM and 4 CPU cores. Recently, users have reported intermittent timeouts and slow response times. The administrator logs in and runs 'top', which shows the web server process using 200% CPU (multi-threaded) and 2GB RAM. Free memory is 12GB, and swap usage is 0. The load average is 3.5, 4.0, 4.2. The administrator checks 'dmesg' and sees no OOM or hardware errors. The web server logs show many 'connection refused' errors during peak times. The application is configured to handle up to 500 concurrent connections. The administrator suspects the issue is related to the number of worker processes or threads. Which of the following is the BEST course of action to resolve the issue?

Accepted Answer

Increase the number of worker processes or threads in the web server configuration.. The web server is using 200% CPU (multi-threaded) and has 12GB free RAM with no swap usage, indicating CPU is the bottleneck, not memory. The load average (3.5–4.2) exceeds the 4 CPU cores, meaning the system is overloaded with processes/threads. The 'connection refused' errors during peak times suggest the server is hitting its connection limit (500 concurrent connections) and rejecting new ones. Increasing worker processes/threads allows the server to handle more concurrent connections, utilizing the available CPU cores more efficiently to reduce timeouts and refusals.

Answer

Add more CPU cores by migrating to a larger instance.

Answer

Decrease the number of worker processes to reduce CPU load.

Answer

Add more RAM to the server.

Question 18

A server has a volume group 'vg_data' with a single logical volume 'lv_data' of 100GB mounted at /data. The filesystem on lv_data is XFS. The administrator needs to extend it to 150GB. A new 60GB disk /dev/sdc has been added and partitioned as LVM. The administrator runs `pvcreate /dev/sdc1`, then `vgextend vg_data /dev/sdc1`, then `lvextend -L +50G /dev/vg_data/lv_data`. The administrator runs `df -h /data` and sees that the filesystem still shows 100GB. Which command should be run next?

Accepted Answer

xfs_growfs /data. For XFS filesystems, after extending the logical volume, the filesystem must be grown using xfs_growfs with the mount point as argument. resize2fs is for ext2/3/4. Option C checks the filesystem, but it's not needed. Option D would shrink, which is incorrect.

Answer

lvreduce -L -50G /dev/vg_data/lv_data

Answer

fsck /dev/vg_data/lv_data

Answer

resize2fs /dev/vg_data/lv_data

Question 19

An administrator notices that a user's crontab file is not executing. Which two commands can the administrator use to verify the user's crontab configuration? (Select TWO.)

Accepted Answer

crontab -l -u username. `crontab -l -u username` lists the current crontab entries for the specified user, allowing the administrator to verify the configured jobs. Option C is correct because on many Linux distributions, user crontab files are stored as plain text files under `/var/spool/cron/crontabs/username`, and reading that file directly shows the same content. Both commands let the administrator inspect the exact cron schedule and commands for that user.

Answer

crontab -e -u username

Answer

systemctl status cron

Answer

grep username /etc/crontab

Question 20

A Linux administrator is writing a Bash script that needs to parse a CSV file line by line and extract the second field. Which of the following approaches is the most efficient?

Accepted Answer

Using `awk -F',' '{print $2}'`. `awk` is purpose-built for field-based text processing; `awk -F',' '{print $2}'` efficiently splits each line by comma and prints the second field without needing an explicit loop. It handles edge cases like empty fields and large files with minimal overhead, making it the most efficient choice for CSV parsing in a script.

Answer

Using a `while read` loop with IFS=','

Answer

Using `cut -d, -f2`

Answer

Using `sed` to extract the second column