XK0-006 Practice Exam 3 — 20 Questions

Question 1

Refer to the exhibit. A web application running under Apache cannot write to /var/log/app.log. The file has permissions 664 and is owned by apache. What is the correct action to allow writes while maintaining SELinux policies?

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

Accepted Answer

Change the SELinux context of the file to httpd_log_t.. The file /var/log/app.log has permissions 664 and is owned by apache, so the web server should be able to write to it. However, SELinux is blocking the write because the file's SELinux context does not match the type expected for files that Apache (httpd) is allowed to write to. Changing the SELinux context to httpd_log_t tells SELinux that this file is a log file that httpd can write to, which resolves the denial while keeping SELinux enforcing.

Answer

Change the ownership to root.

Answer

Set the httpd_can_network_connect boolean.

Answer

Disable SELinux for the httpd daemon.

Question 2

In a Bash script, what is the difference between single quotes and double quotes?

Accepted Answer

Single quotes prevent variable expansion; double quotes allow it.. Single quotes preserve the literal value of each character, while double quotes allow variable expansion and command substitution.

Answer

Both behave the same.

Answer

Single quotes allow variable expansion; double quotes do not.

Answer

Double quotes prevent all substitutions; single quotes allow command substitution.

Question 3

A system administrator is writing a Bash script that must check if a file exists and is readable. Which two test expressions can be used to achieve this? (Choose two.)

Accepted Answer

-e /path/to/file. Option A, `-e /path/to/file`, is correct because the `-e` test in Bash returns true if the file exists, regardless of its type (regular file, directory, device, etc.), which satisfies the existence check. Option C, `-r /path/to/file`, is correct because the `-r` test returns true if the file exists and the current user has read permission on it, satisfying the readability check. Together, `-e` and `-r` cover the two required conditions of existence and readability. Option B, `-s`, only checks that the file exists and has a size greater than zero, so it does not verify readability. Option D, `-x`, checks for execute permission rather than read permission, so it does not meet the requirement. Option E, `-f`, only checks that the path exists and is a regular file, not that it is readable.

Answer

-s /path/to/file

Answer

-x /path/to/file

Answer

-f /path/to/file

Question 4

A Docker container using port 8080 fails to start with the error 'port is already allocated'. Which command should the administrator use to identify the process using that port?

Accepted Answer

ss -tlnp. The `ss -tlnp` command lists TCP listening sockets (`-l`) with numeric addresses (`-n`) and shows the process identifier (PID) and process name (`-p`) that owns each socket. This directly identifies which process has bound port 8080, allowing the administrator to resolve the 'port is already allocated' error.

Answer

ss -tan

Answer

ss -tln

Answer

ss -r

Question 5

A Kubernetes pod has a container that fails with CrashLoopBackOff. The administrator runs 'kubectl logs pod-name' but sees no output. What is the most likely cause?

Accepted Answer

The container exited before writing to stdout, and logs need to be retrieved with 'kubectl logs --previous'.. When a container enters CrashLoopBackOff, it restarts repeatedly. If 'kubectl logs pod-name' shows no output, it means the current (restarted) container has not written anything to stdout yet. The previous instance of the container may have written logs before crashing, and those logs are accessible using 'kubectl logs --previous' to retrieve the output from the terminated container.

Answer

The container has no logging driver configured.

Answer

The log file is rotated and deleted.

Answer

The pod is not scheduled on any node.

Question 6

A storage administrator needs to automate the expansion of an LVM volume group when free space drops below 10%. The script must add a new physical volume from a spare disk. Which of the following commands should be used in the script to add the new disk to the volume group?

Accepted Answer

pvcreate /dev/sdb1 && vgextend vg01 /dev/sdb1. It first uses `pvcreate` to initialize the spare disk partition `/dev/sdb1` as a physical volume, which is a prerequisite for adding it to an LVM volume group. Then `vgextend vg01 /dev/sdb1` adds that initialized physical volume to the existing volume group `vg01`, expanding its total capacity. This two-step process ensures the disk is properly prepared for LVM management before being incorporated into the volume group.

Answer

vgcreate vg01 /dev/sdb

Answer

vgextend vg01 /dev/sdb1

Answer

lvresize -L +100G vg01

Question 7

A server crashed with a kernel panic. After reboot, the administrator wants to analyze the crash dump. Which THREE actions should be taken to ensure a valid core dump is captured and accessible? (Choose THREE.)

Accepted Answer

Configure a dump target in /etc/kdump.conf.. Option A is correct because /etc/kdump.conf is the kdump configuration file where you must specify the dump target (e.g., a raw device, path, NFS, or SSH location) so the vmcore is written to a persistent, accessible location after the crash. Option B is correct because the kdump service (kdump.service) must be enabled and started so the kdump initramfs is loaded and the capture mechanism is armed for the next kernel panic. Option C is correct because the crashkernel=auto (or an explicit size like crashkernel=256M) kernel parameter in the boot loader reserves memory for the secondary kernel that performs the dump; without it, no dump can be captured. Option D is not required to capture a dump; kernel-debuginfo is only needed later for analyzing the vmcore with tools like crash. Option E is incorrect because /var/crash/vmcore is the result of a successful capture, not an action taken to ensure one, and its presence cannot be guaranteed before a crash occurs.

Answer

Install kernel-debuginfo packages.

Answer

Ensure /var/crash has a vmcore file.

Question 8

A system administrator is working with compressed files. Which THREE commands can be used to view their contents? (Select THREE).

Accepted Answer

zgrep. Option A, zgrep, is correct because it searches inside gzip-compressed files directly, decompressing the stream on the fly and printing matching lines without requiring manual extraction. Option C, zcat, is correct because it decompresses gzip files to standard output, allowing their contents to be viewed (often piped to a pager). Option E, zless, is correct because it is a pager wrapper that decompresses gzip files and displays them page by page, making it ideal for viewing compressed content interactively. Options B (cat) and D (less) are not marked correct because they operate on plain uncompressed files and would output raw binary garbage when applied directly to a gzip-compressed file.

Answer

cat

Answer

less

Question 9

An administrator is managing a Kubernetes cluster. A pod is running but not responding as expected. The administrator wants to view the standard output logs from the pod's main container. Which kubectl command should be used?

Accepted Answer

kubectl logs . The kubectl logs command retrieves the standard output (stdout) and standard error (stderr) logs from a pod's container, which is exactly what the administrator needs. By default it targets the main container; if multiple containers exist, -c specifies one. This is the standard way to view application logs without exec'ing into the container.

Answer

kubectl exec <pod-name> -- cat /var/log/app.log

Answer

kubectl get pod <pod-name> -o yaml

Answer

kubectl describe pod <pod-name>

Question 10

A Linux administrator needs to add a new user named 'jdoe' with a home directory and bash shell. Which command accomplishes this?

Accepted Answer

useradd -m -s /bin/bash jdoe. The useradd command creates a new user, and the -m flag creates the home directory, -s sets the shell. useradd -m -s /bin/bash jdoe is correct.

Answer

groupadd -u jdoe -s /bin/bash

Answer

adduser -h /home/jdoe -s bash jdoe

Answer

usermod -m -s /bin/bash jdoe

Question 11

Refer to the exhibit. A user wants to execute the script 'script.sh' but receives a 'Permission denied' error. Which action should be taken to allow execution?

Accepted Answer

Add execute permission with chmod +x script.sh. The 'Permission denied' error indicates the script lacks the execute permission for the user. The `chmod +x script.sh` command adds the execute permission bit to the file's mode, allowing the user to run it as a program. This is the direct and correct fix for the issue.

Answer

Change the owner to the user with chown

Answer

Change the group to the user's primary group

Answer

Set the permissions to 644 with chmod

Question 12

A system is experiencing high CPU usage due to a background process with PID 2345. The administrator wants to reduce the process's priority by 5 without stopping it. Which command should be used?

Accepted Answer

renice -n +5 -p 2345. The correct command is `renice -n +5 -p 2345` because `renice` adjusts the scheduling priority of a running process. A positive niceness value (+5) lowers the priority (makes the process 'nicer' to others), which reduces CPU usage. The `-n` flag specifies the adjustment value, and `-p` identifies the process by PID. This matches the requirement to reduce priority by 5 without stopping the process.

Answer

kill -STOP 2345

Answer

renice -n -5 -p 2345

Answer

kill -9 2345

Question 13

Refer to the exhibit. A Linux administrator created a systemd service file for a custom script. When starting the service, it fails with 'Unit myservice.service entered failed state.' Which of the following is the most likely cause?

Accepted Answer

The ExecStart path is relative. The most likely cause is that the ExecStart path is relative. Systemd requires absolute paths for ExecStart directives; a relative path (e.g., `./script.sh` or just `script.sh`) will cause the unit to fail immediately because systemd cannot resolve the executable location. The error 'entered failed state' typically results from this path resolution failure.

Answer

The service type should be forking

Answer

The service file lacks an [Install] section

Answer

The Requires directive is missing

Question 14

An administrator runs the command `ls -l file.txt` and sees the permissions `-rwsr-xr-x`. What special permission is set on this file?

Accepted Answer

SUID. The 's' in the owner execute position indicates the SUID (Set User ID) permission is set.

Answer

SGID

Answer

Sticky bit

Answer

No special permission

Question 15

A technician needs to check which package provides the file /usr/bin/foo on a CentOS 8 system. Which command should be used?

Accepted Answer

rpm -qf /usr/bin/foo. On RPM-based systems, rpm -qf queries the package that owns a given file.

Answer

rpm -V /usr/bin/foo

Answer

rpm -qi /usr/bin/foo

Answer

rpm -ql /usr/bin/foo

Question 16

A system administrator runs the command 'chmod 4755 /usr/local/bin/backup'. What effect does this have on the file?

Accepted Answer

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

Sets the sticky bit and gives rwxr-xr-x permissions

Answer

Sets the SGID bit and gives rwxr-xr-x permissions

Answer

Sets the SUID bit and gives rwxrwxr-x permissions

Question 17

A Linux server is experiencing intermittent connectivity issues. The administrator reviews the system logs and finds the following messages: 'NETDEV WATCHDOG: eth0: transmit queue 0 timed out'. Which THREE actions are likely to resolve this issue? (Choose three.)

Accepted Answer

Disable NIC offloading features using 'ethtool -K eth0 tx off sg off'.. The 'NETDEV WATCHDOG: eth0: transmit queue 0 timed out' error often indicates that the NIC's hardware offloading features (such as TCP segmentation offload, scatter-gather) are causing the driver to hang or fail to complete transmissions. Disabling these offloads with 'ethtool -K eth0 tx off sg off' forces the CPU to handle packet segmentation and reduces the load on the NIC, which can resolve the timeout.

Answer

Increase the transmit queue length using 'ifconfig eth0 txqueuelen 10000'.

Answer

Change the MTU on the interface to 9000.

Question 18

A server with multiple disks is configured with RAID 5 for performance and redundancy. The administrator notices that write performance is lower than expected. Which RAID level would provide better write performance while still offering fault tolerance with the same number of disks (minimum 4)?

Accepted Answer

RAID 10. RAID 10 (striping of mirrors) provides better write performance than RAID 5 because it does not incur the overhead of calculating and writing parity data on every write operation. With a minimum of four disks, RAID 10 offers fault tolerance (each mirror can survive one disk failure) while delivering the full write speed of the underlying disks, unlike RAID 5 which must update parity across all disks.

Answer

RAID 0

Answer

RAID 6

Answer

RAID 1

Question 19

A user reports that their system is unable to boot after a recent kernel update. The system displays a 'kernel panic' message. Which of the following is the MOST efficient way to boot into a previous kernel version?

Accepted Answer

Select an older kernel from the GRUB menu. The GRUB bootloader stores multiple kernel versions after an update, allowing you to select a previous kernel from its menu at boot time. Choosing an older kernel bypasses the faulty new kernel without requiring additional tools or recovery media, making it the most efficient method to resolve a kernel panic caused by a recent update.

Answer

Use the systemd rescue mode

Answer

Reinstall the operating system

Answer

Boot from a live CD and chroot

Question 20

A cloud engineer needs to automate the deployment of a new virtual machine with a specific configuration using Ansible. Which file format is typically used for Ansible playbooks?

Accepted Answer

YAML. Ansible playbooks are written in YAML (YAML Ain't Markup Language) because it is human-readable, supports complex data structures like lists and dictionaries, and is designed for configuration management. YAML's indentation-based syntax aligns with Ansible's declarative approach, allowing tasks, variables, and handlers to be defined cleanly without the overhead of brackets or tags.

Answer

JSON

Answer

XML

Answer

INI