XK0-006 Practice Test 16 — 15 Questions

Question 1

Refer to the exhibit. An administrator attempts to mount all filesystems and receives an error. What is the most likely cause?

Accepted Answer

The /var directory has been deleted or is missing.

Answer

The /var entry has a wrong filesystem type.

Answer

The UUID for /var is incorrect in fstab.

Answer

The /var filesystem is corrupted.

Question 2

A Linux server is configured to use Pluggable Authentication Modules (PAM). Which file is used to define the authentication order for the 'sshd' service?

Accepted Answer

/etc/pam.d/sshd. In Linux, PAM configuration files for individual services are stored in /etc/pam.d/, with the filename matching the service name. For the sshd service, the file /etc/pam.d/sshd defines the authentication order, including the modules and their control flags (e.g., required, sufficient) that PAM will consult during SSH login. This is the standard location per the Linux PAM architecture, as documented in the pam.conf man page.

Answer

/etc/authselect/sshd

Answer

/etc/security/sshd

Answer

/etc/pam.d/login

Question 3

Refer to the exhibit. A backup script fails every 5 minutes. Which is the most likely cause?

Accepted Answer

The backup script lacks write permission to the destination directory or file.

Answer

The mount point /mnt/backup is not accessible.

Answer

The cron job is running too frequently, causing a race condition.

Answer

The backup script is not executable.

Question 4

An administrator needs to check the current routing table on a Linux system. Which command should be used?

Accepted Answer

ip route. The `ip route` command displays the kernel routing table, showing the paths that packets take to reach network destinations. This is the standard tool on modern Linux systems for viewing and manipulating routing entries, replacing the older `route -n` command.

Answer

dig -t A

Answer

ss -r

Answer

ip neigh

Question 5

A Linux administrator needs to prevent the root user from logging in via SSH. Which directive should be set in /etc/ssh/sshd_config to accomplish this?

Accepted Answer

PermitRootLogin no. The directive `PermitRootLogin no` in `/etc/ssh/sshd_config` explicitly disallows the root user from authenticating via SSH, regardless of the authentication method used. This is the standard way to block root SSH logins while still allowing other users to connect.

Answer

PasswordAuthentication no

Answer

MaxAuthTries 1

Answer

AllowUsers root

Question 6

A Linux administrator is tasked with adding a new 1TB hard drive to a server. The drive has been partitioned and formatted with ext4, resulting in the device /dev/sdb1. The administrator needs the drive to be mounted persistently at /data. After adding an entry to /etc/fstab, the administrator runs 'mount -a' and sees the error: 'mount: /data: mount point does not exist.' Which of the following should the administrator do first to resolve the issue?

Accepted Answer

Create the /data directory with mkdir. The error 'mount point does not exist' indicates that the directory /data has not been created on the filesystem. The mount command requires an existing directory to attach the device to. Creating the /data directory with mkdir resolves this, allowing mount -a to succeed.

Answer

Run mkfs.ext4 on /dev/sdb1

Answer

Reboot the server

Answer

Run fsck on /dev/sdb1

Question 7

An administrator wants to schedule a script to run every Monday at 3 AM. Which crontab entry is correct?

Accepted Answer

0 3 * * 1 /path/to/script. The crontab syntax requires five fields: minute, hour, day of month, month, and day of week. '0 3 * * 1' means minute 0, hour 3 (3 AM), any day of month (*), any month (*), and day of week 1 (Monday). This precisely schedules the script to run at 3:00 AM every Monday.

Answer

* 3 * * 1 /path/to/script

Answer

0 3 * * * /path/to/script

Answer

0 3 1 * * /path/to/script

Question 8

After a system update, a server takes significantly longer to boot. The administrator wants to identify which systemd service is causing the delay. Which command provides a detailed analysis of boot time spent by each service?

Accepted Answer

systemd-analyze blame. The `systemd-analyze blame` command prints a list of all running systemd units, sorted by the time they took to initialize during boot. This directly answers the administrator's need to identify which specific service is causing the delay, as it shows the exact time spent by each service.

Answer

systemd-analyze time

Answer

systemd-analyze critical-chain

Answer

systemd-analyze plot

Question 9

A Linux administrator is writing a bash script that must exit immediately if any command fails. Which of the following should be included at the beginning of the script?

Accepted Answer

set -e. The set -e command causes the shell to exit if any command exits with a non-zero status, which is exactly what is needed to ensure the script stops on failure.

Answer

set -o pipefail

Answer

set -u

Answer

set -x

Question 10

A Linux administrator writes a Bash script and includes the line `#!/bin/bash` at the top. What is the purpose of this line?

Accepted Answer

It specifies the interpreter to execute the script.. The shebang line tells the system which interpreter to use to execute the script. In this case, it specifies the Bash shell.

Answer

It sets the script to run in the background.

Answer

It enables debugging mode.

Answer

It defines a variable for the script.

Question 11

A DevOps engineer is writing a Bash script that iterates over all items in an array. The array is declared as 'fruits=("apple" "banana" "cherry")'. Which loop correctly iterates over each element?

Accepted Answer

for fruit in "${fruits[@]}"; do ... done. To iterate over array elements, use "${fruits[@]}" with quotes. The @ expands to all elements.

Answer

for (i=0; i<${#fruits[@]}; i++); do ... done

Answer

for fruit in ${fruits[*]}; do ... done

Answer

for fruit in $fruits; do ... done

Question 12

A container is running and a technician needs to execute an interactive shell inside it. The container was started with 'docker run -d --name myapp myimage'. Which command will achieve this?

Accepted Answer

docker exec -it myapp /bin/bash. docker exec -it myapp /bin/bash runs an interactive shell inside the running container.

Answer

docker attach myapp

Answer

docker run -it --name myapp myimage /bin/bash

Answer

docker logs -f myapp

Question 13

A DevOps team is designing a containerized application using Docker Compose. They need to ensure that the database container is started before the application container. Which of the following Docker Compose directives can be used to control startup order? (Choose TWO.)

Accepted Answer

depends_on. depends_on ensures that the specified services are started first. healthcheck can be used to wait for a service to be healthy before starting dependent services.

Answer

volumes

Answer

links

Answer

environment

Question 14

An administrator wants to run a script on multiple remote servers using Ansible. The script requires a variable that differs per host. Where should the administrator define this variable to follow best practices?

Accepted Answer

In host_vars/<hostname>.yml. Host-specific variables should be defined in host_vars files, which are automatically loaded by Ansible when the host is targeted.

Answer

In the playbook under vars:

Answer

In the inventory file as a variable

Answer

In group_vars/all.yml

Question 15

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. The -e test checks if a file exists, and -r checks if it is readable. The -f test checks if it is a regular file, which also implies existence but not necessarily readable. The question asks for existence and readability, so -e and -r are correct.

Answer

-s /path/to/file

Answer

-x /path/to/file

Answer

-f /path/to/file