XK0-006 Practice Test 2 — 10 Questions

Question 1

A cron job runs a script that produces output, but the administrator does not receive the expected email notification. Which is the most likely cause?

Accepted Answer

MAILTO variable is not set in the crontab.. The MAILTO variable in a crontab specifies the email address to which cron sends the output (stdout/stderr) of a job. If MAILTO is not set, cron defaults to mailing output to the owner of the crontab (the user who created it). However, if the administrator expects notifications at a different address, the missing MAILTO variable would prevent that specific email from being sent. This is the most direct cause of not receiving the expected email notification.

Answer

The script uses absolute paths for all commands.

Answer

The PATH environment variable is not set.

Answer

The script is not executable.

Question 2

Which TWO of the following are valid methods to enforce disk quota limits on a Linux filesystem? (Select TWO.)

Accepted Answer

Using 'edquota' to set soft and hard limits for users. 'edquota' is the standard interactive command used to set soft and hard disk quota limits for users or groups on a Linux filesystem. It opens the user's quota settings in a text editor, allowing precise configuration of block and inode limits. Option E is correct because 'quotaon' is the command that enables quota enforcement on a specified filesystem, activating the quota subsystem after limits have been defined.

Answer

Using 'setquota' to set limits in a script

Answer

Running 'repquota' to generate reports

Answer

Running 'quotacheck' to update quota files

Question 3

A Linux administrator is hardening an SSH server. Which two of the following settings should be applied to /etc/ssh/sshd_config to improve security?

Accepted Answer

PermitRootLogin no. PermitRootLogin no prevents root login; PasswordAuthentication no forces key-based authentication. Changing the port and enabling X11 forwarding are not necessarily hardening.

Answer

Port 2222

Answer

X11Forwarding yes

Answer

Protocol 1

Question 4

During a security audit, a Linux administrator finds that an unauthorized service is listening on TCP port 4444. The service is not managed by systemd. Which of the following commands should the administrator use to identify the process and disable it?

Accepted Answer

Run 'ss -tlnp | grep :4444' to find the PID, then use 'kill' to terminate the process.. 'ss -tlnp' lists TCP listening sockets with numeric addresses and the associated process PID. Piping the output through 'grep :4444' isolates the unauthorized service, and the PID can then be used with 'kill' to terminate the process. Since the service is not managed by systemd, systemctl commands are irrelevant, making 'kill' the appropriate method to stop the process.

Answer

Run 'fuser 4444/tcp' to find the PID and then use 'systemctl stop' to stop the service.

Answer

Run 'lsof -i :4444' to find the PID, then use 'systemctl disable' to disable the service.

Answer

Run 'systemctl status' to find the service name, then use 'systemctl stop' to stop it.

Question 5

A Linux administrator is writing a Bash script to automate the backup of a database. The script must run a pre-backup command, check its exit status, and if successful, proceed with the backup; otherwise, log an error and exit. Which code snippet correctly implements this logic?

Accepted Answer

pre_backup_cmd
if [ $? -ne 0 ]; then echo 'Error' >&2; exit 1; fi
backup_cmd. Ly runs the pre-backup command, then checks its exit status with `$?`. If the exit status is not zero (indicating failure), it logs an error to stderr and exits with code 1. Only if the pre-backup command succeeds does the script proceed to the backup command. This matches the requirement exactly: check exit status, log error on failure, and exit.

Answer

set -e
pre_backup_cmd
backup_cmd

Answer

pre_backup_cmd && backup_cmd || echo 'Error' >&2

Answer

(pre_backup_cmd; if [ $? -ne 0 ]; then echo 'Error' >&2; exit 1; fi) && backup_cmd

Question 6

A system fails to boot with a kernel panic. The administrator suspects a corrupt initramfs or missing kernel module. Which three methods could be used to recover the system? (Choose three.)

Accepted Answer

Boot from a live CD/DVD, mount the root filesystem, and chroot. At the GRUB menu, editing boot parameters to add 'rd.break' drops into an emergency shell; adding 'single' boots into single-user mode; booting from a live CD allows chroot and repair.

Answer

Run 'fsck /dev/sda1' from the GRUB command line

Answer

Use 'systemctl rescue' from the boot prompt

Question 7

A web server in a remote data center logs timestamps in UTC, but the operations team wants all logs to reflect the local timezone (America/New_York). Which command changes the system timezone?

Accepted Answer

timedatectl set-timezone America/New_York. The `timedatectl set-timezone` command is the correct way to change the system timezone on a Linux system using systemd. By specifying 'America/New_York', the system will adjust all timestamps to Eastern Time, including those generated by the web server, ensuring logs reflect the local timezone.

Answer

timedatectl set-time '2025-03-01 12:00:00'

Answer

timedatectl list-timezones

Answer

timedatectl set-ntp yes

Question 8

Which of the following correctly describes the purpose of the /etc/shadow file?

Accepted Answer

It stores encrypted passwords and password aging fields.. The /etc/shadow file stores encrypted (hashed) user passwords and password aging information such as the date of last password change, minimum/maximum password age, and account expiration. This file is readable only by root to protect password hashes from unauthorized access, unlike /etc/passwd which is world-readable.

Answer

It stores the list of users who can use sudo.

Answer

It stores group memberships and group passwords.

Answer

It stores user account information including UID, GID, and shell.

Question 9

A junior administrator is asked to automate the backup of a configuration file every night at 11 PM. The script /usr/local/bin/backup.sh already exists. Which command should the administrator run to schedule this task?

Accepted Answer

echo "0 23 * * * /usr/local/bin/backup.sh" | crontab -. The `crontab -` command reads from standard input and installs the cron job. The line `0 23 * * * /usr/local/bin/backup.sh` specifies that the script should run at 23:00 (11 PM) every day, matching the requirement exactly. This is the standard method for scheduling recurring tasks in Linux using cron.

Answer

systemctl start backup.timer

Answer

at 23:00 /usr/local/bin/backup.sh

Answer

nohup /usr/local/bin/backup.sh &

Question 10

A system administrator is configuring firewalld on a Linux server. They want to allow incoming HTTPS traffic permanently for the public zone. Which command should be used?

Accepted Answer

firewall-cmd --add-service=https --zone=public --permanent. The `firewall-cmd --add-service=https --zone=public --permanent` command adds the HTTPS service (TCP port 443) to the public zone and makes the rule persistent across reboots. The `--permanent` flag ensures the change survives a firewall reload or system restart, and the `--zone=public` targets the correct network zone for incoming traffic.

Answer

firewall-cmd --zone=public --add-service=https

Answer

firewall-cmd --service=https --add --zone=public --permanent

Answer

firewall-cmd --add-port=443/tcp --zone=public --permanent