XK0-006 Practice Test 5 — 25 Questions

Question 1

An administrator wants to monitor real-time system resource usage to identify performance bottlenecks. Which two commands are suitable? (Choose two.)

Accepted Answer

top. top and htop provide real-time process and resource monitoring.

Answer

vmstat

Answer

iostat

Answer

sar

Question 2

Which TWO statements are true regarding the use of Ansible for automation? (Choose TWO.)

Accepted Answer

Ansible playbooks are written in YAML.. Ansible playbooks are written in YAML (YAML Ain't Markup Language), which is a human-readable data serialization standard. YAML allows for simple, declarative syntax to define automation tasks, variables, and handlers, making playbooks easy to write and maintain without requiring programming expertise.

Answer

Ansible requires a dedicated master server to manage nodes.

Answer

Ansible uses a pull-based model where nodes fetch configurations from a central server.

Answer

Ansible modules are written in Ruby.

Question 3

A junior administrator is writing a bash script that should exit immediately if any command in a pipeline fails. Which command should be added at the beginning of the script?

Accepted Answer

set -o pipefail. `set -o pipefail` ensures that if any command in a pipeline fails (returns a non-zero exit status), the entire pipeline is considered to have failed, and with `set -e` (which is often used alongside it), the script will exit immediately. This is specifically required by the question: 'exit immediately if any command in a pipeline fails.' Without `pipefail`, only the exit status of the last command in the pipeline is considered, so earlier failures would be ignored.

Answer

set -u

Answer

shopt -s extglob

Answer

set -e

Question 4

An administrator wants to locate files that have the SUID or SGID special permission set. Which three find commands can accomplish this? (Choose three.)

Accepted Answer

find / -perm /6000. The find command with -perm can search for permissions in symbolic or octal modes, and using -4000 or -2000 finds SUID or SGID respectively.

Answer

find / -perm 2000

Answer

find / -perm 4000

Question 5

A system administrator is configuring a new disk partition for a database server. The disk has been partitioned as /dev/sdb1. Which three steps are necessary to make the filesystem available for use? (Choose three.)

Accepted Answer

Mount the partition with mount. To use a new partition, you must create a filesystem (mkfs), mount it (mount), and add an entry to /etc/fstab for persistent mounting.

Answer

Run fsck to check the filesystem

Answer

Set a label with e2label

Question 6

Which command would a Linux administrator use to locate all files in the /var/log directory that have been modified within the last 7 days?

Accepted Answer

find /var/log -mtime -7. The find command with -mtime -7 finds files modified less than 7 days ago. The other options are either incorrect or not suitable for this task.

Answer

ls -lt /var/log | head -n 7

Answer

grep -mtime -7 /var/log

Answer

locate -mtime -7 /var/log

Question 7

A Linux system is experiencing kernel panics after a recent update. The administrator wants to boot into a previous kernel version to restore functionality. Which three steps are required to achieve this? (Select THREE).

Accepted Answer

After booting, edit /etc/default/grub and set GRUB_DEFAULT to the saved entry, then run update-grub. After booting into a working kernel, editing /etc/default/grub to set GRUB_DEFAULT to 'saved' and running update-grub (or grub-mkconfig) ensures that the GRUB bootloader will remember and default to the last successfully booted kernel, which can be the previous version. This step is necessary to make the temporary fix persistent across reboots.

Answer

Run 'yum reinstall kernel' to revert to the previous version

Answer

Edit /etc/fstab to change root filesystem parameters

Question 8

An administrator wants to display the last 20 lines of a log file and also write those lines to a file called recent.log. Which command should be used?

Accepted Answer

tail -n 20 file | tee recent.log. tail -n 20 file | tee recent.log displays the last 20 lines and writes them to recent.log. tee is used to split output to file and stdout.

Answer

tail -n 20 file > recent.log

Answer

head -n 20 file > recent.log

Answer

cat file | head -n 20 > recent.log

Question 9

Which THREE are valid methods to view logs in a systemd-based system?

Accepted Answer

journalctl. B is correct because `journalctl` is the primary command for querying the systemd journal, which is the default logging system on systemd-based distributions. It provides structured, binary logs with advanced filtering, and is the direct equivalent of viewing logs via the journal.

Answer

cat /var/log/messages

Answer

systemctl status sshd

Question 10

A file has permissions set to 2755. Which special permission is enabled, and what does it do?

Accepted Answer

SGID; new files in the directory inherit the group. The permission 2755 includes the SGID (Set Group ID) special permission, indicated by the leading digit '2'. When SGID is set on a directory, new files and subdirectories created within it inherit the group ownership of the directory, rather than the primary group of the user who creates them. This is critical for collaborative environments where multiple users need shared group access.

Answer

No special permission; it is just octal 755

Answer

Sticky bit; only file owners can delete their files

Answer

SUID; the file runs with the owner's privileges

Question 11

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 12

A Linux administrator uses Podman for container management. Which TWO commands display a list of currently running containers?

Accepted Answer

podman container ls. `podman container ls` is the explicit Podman command to list running containers, equivalent to `podman ps`. Option E is also correct because `podman ps` is the standard shorthand for listing running containers in Podman, mirroring Docker's `docker ps` syntax. Both commands display the same output of currently active containers.

Answer

docker ps

Answer

podman inspect

Answer

podman images

Question 13

A system administrator wants to limit the CPU and memory usage of a specific service to prevent it from affecting other processes. Which Linux feature should be used?

Accepted Answer

cgroups. C is correct because cgroups (control groups) is the Linux kernel feature designed to limit, account for, and isolate resource usage (CPU, memory, disk I/O, etc.) of process groups. Unlike simple priority adjustments, cgroups enforce hard limits on resource consumption, making them ideal for preventing a specific service from starving other processes.

Answer

ulimit

Answer

renice

Answer

nice

Question 14

An administrator needs to identify which processes are consuming the most CPU and memory resources. Which two commands can provide this information? (Choose two.)

Accepted Answer

top. The `top` command provides a real-time, dynamic view of running processes, displaying CPU and memory usage by default and allowing sorting by resource consumption. The `ps aux --sort=-%mem` command lists all processes with detailed memory and CPU statistics, sorted by memory usage in descending order, making it easy to identify the most resource-intensive processes.

Answer

free -h

Answer

iostat -x

Answer

vmstat 1 5

Question 15

An administrator needs to allow a user to run all commands as root without a password. Which sudoers entry accomplishes this?

Accepted Answer

user ALL=(ALL) NOPASSWD: ALL. The sudoers entry `user ALL=(ALL) NOPASSWD: ALL` grants the user permission to run any command as any user (including root) without being prompted for a password. The `NOPASSWD` tag overrides the default password requirement, and the `ALL` specifications cover the host list, target user list, and command list.

Answer

user ALL=(ALL) !ALL

Answer

user ALL=(ALL) PASSWD: ALL

Answer

user ALL=(ALL) ALL

Question 16

A Linux administrator needs to configure a firewall to allow incoming SSH connections only from the 192.168.1.0/24 subnet. The current iptables INPUT policy is ACCEPT. Which set of rules should be added?

Accepted Answer

iptables -A INPUT -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT; iptables -A INPUT -p tcp --dport 22 -j DROP. Iptables processes rules in order, and the first matching rule determines the action. By placing the ACCEPT rule for the 192.168.1.0/24 subnet first, SSH traffic from that subnet is accepted. The subsequent DROP rule for port 22 then denies all other SSH traffic. This ensures that only the specified subnet can connect, while the default ACCEPT policy on the INPUT chain would otherwise allow all traffic if no rule matched.

Answer

iptables -A INPUT -p tcp --dport 22 -j DROP; iptables -A INPUT -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT

Answer

iptables -A INPUT -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT; iptables -A INPUT -p tcp --dport 22 -s 10.0.0.0/8 -j DROP

Answer

iptables -I INPUT -p tcp --dport 22 -j DROP; iptables -A INPUT -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT

Question 17

After a security audit, it is recommended to disable SSH password authentication in favor of key-based authentication. Which configuration line should be set in /etc/ssh/sshd_config?

Accepted Answer

PasswordAuthentication no. Disabling password authentication forces SSH to use key-based authentication, which is more secure against brute-force attacks. Setting `PasswordAuthentication no` in `/etc/ssh/sshd_config` prevents SSH from prompting for a password, requiring a valid SSH key pair for authentication. This aligns with the security audit's recommendation to disable password authentication in favor of key-based authentication.

Answer

PasswordAuthentication yes

Answer

PubkeyAuthentication no

Answer

ChallengeResponseAuthentication yes

Question 18

An administrator is investigating a system that may have been compromised. The 'aide' database was created six months ago. After running 'aide --check', many files in /usr/bin are reported as changed. Which action should the administrator take first to identify the cause?

Accepted Answer

Compare the checksums with the original package manager database (rpm -V).. The AIDE database is six months old, so any changes to system binaries in /usr/bin since then would be flagged. The first step should be to verify whether these changes are legitimate (e.g., from package updates) or malicious by comparing the current file checksums against the RPM package manager's database using 'rpm -V'. This distinguishes expected updates from unauthorized modifications without relying on the outdated AIDE baseline.

Answer

Increase the verbosity of AIDE to see which attributes changed.

Answer

Update the AIDE database with 'aide --update'.

Answer

Restore the original files from backup.

Question 19

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 20

Which command creates a symbolic link named 'link.txt' that points to 'original.txt'?

Accepted Answer

ln -s original.txt link.txt. ln -s target link_name creates a symbolic link.

Answer

symlink original.txt link.txt

Answer

ln original.txt link.txt

Answer

ln -s link.txt original.txt