XK0-006 Practice Test 32 — 15 Questions

Question 1

A company runs a critical web application on a single Linux server. The application consists of a Node.js backend and a PostgreSQL database. The server is running out of disk space frequently due to application logs. The administrator wants to implement a log rotation solution that is automated, minimizes data loss, and compresses old logs. The administrator has root access and wants to use built-in tools. Currently, logs are written to /var/log/app/access.log and /var/log/app/error.log. The application never closes its log files. Which of the following is the best course of action?

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

Accepted Answer

Configure logrotate with daily rotation, compression, and the copytruncate option.. Logrotate with the copytruncate option allows the log file to be rotated without requiring the application to close or reopen its file handles. This is essential since the application never closes its log files. Daily rotation with compression addresses the frequent disk space issue while minimizing data loss, and logrotate is a built-in Linux tool that runs automatically via cron.

Answer

Configure the systemd journal to capture the application logs and set MaxRetentionSec.

Answer

Create a cron job that runs every hour to move the logs to a backup directory and restart the application.

Answer

Configure logrotate with a weekly rotation and no copytruncate, since the application will eventually close the log files.

Question 2

A Linux administrator receives reports that a web application hosted on the company's internal server is intermittently slow. The server runs CentOS 7 and hosts multiple virtual hosts. The administrator checks system resources and notices that the system's swap usage is high. Which of the following is the MOST likely cause of the performance issue?

Accepted Answer

Insufficient physical memory for the workload. High swap usage indicates that the system is actively paging memory to disk because the available physical RAM is insufficient to hold the active working set. This causes significant latency because disk I/O is orders of magnitude slower than RAM, leading to intermittent slowdowns for the web application. The fact that multiple virtual hosts are running on CentOS 7 increases the memory demand, making insufficient physical memory the most likely root cause.

Answer

Misconfigured virtual host causing memory leaks

Answer

Network congestion on the internal network

Answer

Excessive CPU load from a runaway process

Question 3

A Linux system experiences high CPU usage from a process that appears to be a fork bomb. The administrator wants to prevent such attacks in the future by limiting the number of processes a user can create. Which configuration file should be modified, and what parameter should be set?

Accepted Answer

Add 'username hard nproc 100' in /etc/security/limits.conf. /etc/security/limits.conf is the PAM-based configuration file used to set per-user resource limits via the 'nproc' parameter. Adding 'username hard nproc 100' enforces a hard limit of 100 processes for that user, preventing a fork bomb from exhausting system resources.

Answer

Set 'kernel.pid_max=100' in /etc/sysctl.conf

Answer

Set 'DefaultLimitNPROC=100' in /etc/systemd/system.conf

Answer

Add 'ulimit -u 100' to /etc/profile

Question 4

Which TWO commands are used to view logs in a systemd-based system? (Choose two.)

Accepted Answer

dmesg. C is correct because `dmesg` reads the kernel ring buffer, which contains boot-time and hardware-related log messages, and is commonly used to view logs on systemd-based systems. D is correct because `journalctl` is the primary command for querying and viewing logs from systemd's journal (managed by `systemd-journald`), which is the default logging subsystem in systemd-based distributions.

Answer

tail -f /var/log/messages

Answer

syslog

Answer

systemctl

Question 5

A system administrator notices that a critical application's process is consuming too much CPU, affecting other services. The administrator needs to reduce the CPU priority of that process without affecting its memory or other resources. The process PID is 4521. Which command should the administrator use?

Accepted Answer

renice -n 10 -p 4521. The `renice` command is used to change the priority of an already running process. By specifying `-n 10` and `-p 4521`, the administrator sets the nice value to 10, which lowers the CPU priority (higher nice value = lower priority) without affecting the process's memory or other resources. This directly addresses the need to reduce CPU consumption for the critical application.

Answer

nice -n 10 -p 4521

Answer

renice -p 4521 10

Answer

chrt -p 10 4521

Question 6

A system administrator notices that a service fails to start at boot with the message "Failed to start MyApp.service: Unit not found". The administrator checks the service unit file at /etc/systemd/system/myapp.service. The target wanted-by is multi-user.target. The administrator runs `systemctl enable myapp.service` successfully, but the service still does not start at boot. What is the most likely cause?

Accepted Answer

The systemd daemon has not been reloaded after enabling.. When `systemctl enable myapp.service` is run, systemd creates the necessary symlinks in the `.wants` directory but does not automatically reload its configuration. The service fails to start at boot because systemd still holds the old configuration in memory and does not recognize the newly enabled unit. Running `systemctl daemon-reload` forces systemd to re-read all unit files and apply the new enablement, allowing the service to start at boot.

Answer

The service unit file has a syntax error.

Answer

The service requires a dependency that is not installed.

Answer

The service is not symlinked into the correct .wants directory.

Question 7

An administrator needs to run a container using a specific user ID to match host file permissions. Which Docker option should be used when running the container?

Accepted Answer

-u 1001. The `-u` (or `--user`) option in Docker allows you to run the container process with a specific user ID (UID) instead of the default root (UID 0). By specifying `-u 1001`, the container's main process will run as UID 1001, which can be matched to a host user's UID to ensure proper file ownership and permissions when accessing mounted volumes. This is essential for avoiding permission denied errors when the container writes files to a bind-mounted host directory.

Answer

-e USER=1001

Answer

-v /host:/container

Answer

--name mycontainer

Question 8

An administrator needs to set up a new LVM volume. Which two commands are necessary in the initial setup before creating a logical volume?

Accepted Answer

vgcreate. Before creating a logical volume (LV), you must first prepare the physical storage devices and then group them into a volume group. The `pvcreate` command initializes a block device (e.g., /dev/sdb) as a physical volume (PV) by writing LVM metadata to it. The `vgcreate` command then creates a volume group (VG) from one or more PVs, which serves as the pool of storage from which logical volumes are carved. Without these two steps, the LVM subsystem has no recognized storage to allocate.

Answer

mount

Answer

lvcreate

Answer

mkfs

Question 9

A Linux administrator is troubleshooting a service that fails to start. Which THREE files or commands should be checked to diagnose the issue? (Select THREE.)

Accepted Answer

journalctl -u service-name. B is correct because `journalctl -u service-name` displays the systemd journal logs specifically for that service, which includes detailed error messages, timestamps, and status changes that are essential for diagnosing why the service failed to start. This command is the primary tool for viewing service-specific logs in modern systemd-based Linux distributions.

Answer

dmesg

Answer

/etc/rc.local

Question 10

The sysadmin receives the error shown in the exhibit. What is the most likely fix?

Accepted Answer

Add limits to the resources section.. The error indicates the container was killed due to an Out Of Memory (OOM) condition. Adding limits to the resources section constrains the container's memory usage, preventing it from exceeding the node's capacity and being terminated by the kernel OOM killer.

Answer

Add a readiness probe to the container.

Answer

Change the image tag to :latest.

Answer

Remove the requests section.

Question 11

An administrator wants to use Ansible to ensure that the `httpd` package is installed on all managed nodes. Which Ansible module should be used?

Accepted Answer

yum. The `yum` module is the correct choice because it is a dedicated Ansible module for managing packages on Red Hat-based systems using the YUM package manager. It ensures the `httpd` package is installed by setting the `state: present` parameter, and it handles idempotency by checking the package status before making changes.

Answer

copy

Answer

command

Answer

service

Question 12

A container started with the above Compose configuration fails to set the system time (clock_settime syscall). Which additional capability is required?

Accepted Answer

SYS_TIME. The `clock_settime` syscall requires the `SYS_TIME` capability to modify the system clock. In Docker Compose, capabilities are added via the `cap_add` directive, and without `SYS_TIME`, the container lacks the privilege to change the system time, resulting in a failure.

Answer

SYS_NICE

Answer

SYS_RESOURCE

Answer

SYS_CLOCK

Question 13

An administrator wants to verify which RPM packages are installed on a Red Hat Enterprise Linux system. Which command displays that information?

Accepted Answer

rpm -qa. The `rpm -qa` command queries the RPM database and lists all installed packages on a Red Hat Enterprise Linux system. The `-q` flag enables query mode, and `-a` specifies all packages, making it the correct tool for this task.

Answer

dpkg -l

Answer

apt list --installed

Answer

yum list installed

Question 14

You are managing a containerized microservices environment using Podman. One of the services needs to access a PostgreSQL database running in a separate container. The database container is named 'db' and uses the default bridge network. The application container is launched with the command: podman run -d --name app --network host myapp. The application fails to connect to the database using the hostname 'db'. Which change should you resolve the issue?

Accepted Answer

Use a user-defined network and connect both containers. The default bridge network in Podman does not provide automatic DNS resolution between containers by name. When the app container uses `--network host`, it shares the host's network stack and is not connected to any container network, so it cannot resolve the container name 'db'. A user-defined network enables built-in DNS resolution, allowing containers to communicate by name. Connecting both containers to the same user-defined network resolves the connectivity issue.

Answer

Use --link db:db when running app container

Answer

Set environment variable DB_HOST=localhost

Answer

Run app container on the same network as db using --network bridge

Question 15

A security administrator needs to verify the SELinux context of files in a directory. Which TWO commands can be used? (Choose two.)

Accepted Answer

ls -Z. The `ls -Z` command displays the SELinux security context of files in a directory, showing the user, role, type, and sensitivity level. The `stat -Z` command also retrieves the SELinux context along with other file metadata, making both commands valid for verifying SELinux contexts.

Answer

getenforce

Answer

ps -Z

Answer

chcon