XK0-005 Practice Test 26 — 15 Questions

Question 1

A Linux administrator needs to configure a service to start automatically after a network connection is established. The service should only run when the network is up, and should stop when the network goes down. Which two systemd unit options should be used? (Choose two.)

Accepted Answer

BindsTo=network.target. After=network.target ensures the service starts after network is configured. BindsTo=network.target ties the service lifecycle to the network target; if network goes down, the service stops. Requires does not imply ordering; Wants is weaker; PartOf is for resource partitioning.

Answer

Requires=network.target

Answer

PartOf=network.service

Answer

Wants=network.target

Question 2

A system administrator needs to configure a Linux server to automatically synchronize time with the NTP pool servers. The server should also act as an NTP peer for other servers on the local network. Which file should be modified, and which directive should be added?

Accepted Answer

/etc/chrony/chrony.conf with "pool pool.ntp.org iburst" and "allow 192.168.1.0/24". Chrony is the default NTP implementation on modern RHEL/CentOS 7+ and many distributions. The configuration file is /etc/chrony/chrony.conf. The 'pool' directive with 'iburst' synchronizes with NTP servers, and 'allow' specifies which networks can query the server as an NTP peer. Option A uses ntpd but lacks the 'allow' directive. Option C uses timesyncd which is client-only. Option D has typo and incorrect directive.

Answer

/etc/npt.conf with "peer pool.ntp.org"

Answer

/etc/systemd/timesyncd.conf with "NTP=pool.ntp.org" and "LocalPort=123"

Answer

/etc/ntp.conf with "server pool.ntp.org iburst"

Question 3

Refer to the exhibit. A system administrator checks the status of the SSH service and sees the output shown. What is the most likely cause of the failure?

Accepted Answer

Another process is already listening on port 22.

Answer

The SSH service is disabled and needs to be enabled.

Answer

The SSH service is masked and cannot start.

Answer

The SSH configuration file has a syntax error.

Question 4

Refer to the exhibit. A network administrator is troubleshooting a failed network connection. Based on the journalctl output, what is the most likely cause?

Accepted Answer

The network interface eth0 is not physically connected.

Answer

The NetworkManager service is not running.

Answer

The network configuration file has an invalid IP address.

Answer

The DHCP server is unreachable.

Question 5

Refer to the exhibit. Users report they cannot SSH to the server. Based on the logs, what is the most likely cause?

Accepted Answer

Host keys are missing or corrupted.

Answer

Firewall is blocking port 22.

Answer

The SSH service is not running.

Answer

SSH configuration has incorrect permissions.

Question 6

Refer to the exhibit. An administrator can SSH to the server but cannot ping 10.0.0.1. What is the most likely cause?

Accepted Answer

The destination host 10.0.0.1 is not responding to ping due to a firewall or ICMP being disabled on that host.

Answer

The ping is being blocked by the nftables output chain, which is not configured.

Answer

ICMP is blocked by the nftables input chain policy drop.

Answer

The destination host 10.0.0.1 does not have a route back.

Question 7

Which TWO commands can be used to change the group ownership of a file? (Choose exactly two.)

Accepted Answer

chgrp. The `chgrp` command is specifically designed to change the group ownership of a file or directory. The `chown` command can also change group ownership when used with the colon syntax (e.g., `chown :groupname file`). Both commands modify the file's group ID (GID) in the inode metadata.

Answer

chmod

Answer

groupmod

Answer

usermod

Question 8

A web server is running on the system but clients cannot connect to port 8080. Based on the exhibit, which command should the administrator run to allow traffic on port 8080?

Accepted Answer

firewall-cmd --add-port=8080/tcp --permanent. The correct command is `firewall-cmd --add-port=8080/tcp --permanent` because it opens TCP port 8080 in firewalld, which is the default firewall management tool on RHEL/CentOS 8/9. Since the web server is running but clients cannot connect, the firewall is likely blocking inbound traffic on that port. The `--add-port` option with the `tcp` protocol explicitly allows TCP connections, and `--permanent` makes the rule persist across reboots.

Answer

firewall-cmd --add-rich-rule='rule port port=8080 protocol=tcp accept' --permanent

Answer

firewall-cmd --add-port=8080/udp --permanent

Answer

firewall-cmd --add-service=http --permanent

Question 9

A systems administrator is troubleshooting a server that fails to boot and displays the error: 'Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)'. Which TWO of the following are most likely causes? (Choose two.)

Accepted Answer

Missing or misconfigured root filesystem in /etc/fstab. Option A is correct because the error 'VFS: Unable to mount root fs on unknown-block(0,0)' indicates the kernel cannot locate or mount the root filesystem. A missing or misconfigured root filesystem entry in /etc/fstab (e.g., wrong device name, wrong UUID, or missing entry) prevents the kernel from mounting the root partition, leading to a kernel panic. The 'unknown-block(0,0)' specifically means the kernel cannot resolve the block device for the root filesystem.

Answer

Faulty RAM

Answer

Overwritten MBR

Answer

Incorrect boot loader configuration pointing to wrong kernel

Question 10

A technician runs the command `sudo lvdisplay /dev/vg_root/lv_root` and sees the output in the exhibit. The server fails to mount the root filesystem during boot. Which of the following should the technician do first?

Accepted Answer

Run `lvchange -ay /dev/vg_root/lv_root` to activate the logical volume.. The `lvdisplay` output shows the logical volume is present but its 'LV Status' is likely 'NOT available' (not shown in the exhibit but implied by the boot failure). The root filesystem cannot mount because the logical volume is inactive. The first corrective step is to activate it with `lvchange -ay /dev/vg_root/lv_root`, which makes the LV accessible to the kernel for mounting.

Answer

Run `fsck /dev/vg_root/lv_root` to check the filesystem.

Answer

Run `vgchange -ay` to activate the volume group.

Answer

Run `mount /dev/vg_root/lv_root /mnt` to mount the volume.

Question 11

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

Accepted Answer

podman container ls. Option D is correct because `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 12

A Linux server is not accepting SSH connections. The administrator wants to troubleshoot the issue. Which THREE actions should be taken?

Accepted Answer

Check /etc/ssh/sshd_config for configuration errors. B is correct because /etc/ssh/sshd_config is the primary configuration file for the OpenSSH server. Syntax errors, incorrect directives (e.g., PermitRootLogin no, Port 22 commented out), or misconfigured authentication settings can prevent SSH from accepting connections. Checking this file is a fundamental step in troubleshooting SSH issues.

Answer

Reboot the server

Answer

Reinstall the SSH package (apt reinstall openssh-server)

Question 13

The company password policy requires minimum length, complexity, and that passwords cannot be based on dictionary words. Which file should be edited to configure these settings via pam_pwquality?

Accepted Answer

/etc/security/pwquality.conf. The pam_pwquality module enforces password quality rules such as minimum length, complexity, and dictionary checks. Its configuration file is /etc/security/pwquality.conf, where parameters like minlen, dcredit, ucredit, lcredit, ocredit, and dictcheck are set. Editing this file directly controls the PAM module's behavior without modifying PAM service files.

Answer

/etc/login.defs

Answer

/etc/pam.d/system-auth

Answer

/etc/pam.d/password-auth

Question 14

A security audit reveals a misconfiguration. Which file has insecure permissions that could allow unauthorized users to read password hashes?

Accepted Answer

/etc/shadow. The /etc/shadow file stores password hashes and should be readable only by the root user (typically permissions 640 or 600). If its permissions are too permissive (e.g., world-readable), any local user could read the hashes and attempt offline cracking. This is the misconfiguration the audit would flag.

Answer

Both files are misconfigured

Answer

Neither file has a misconfiguration

Answer

/etc/passwd

Question 15

An administrator notices that a user's crontab file is not executing. Which two commands can the administrator use to verify the user's crontab configuration? (Select TWO.)

Accepted Answer

crontab -l -u username. Option B is correct because `crontab -l -u username` lists the current crontab entries for the specified user, allowing the administrator to verify the configured jobs. Option C is correct because on many Linux distributions, user crontab files are stored as plain text files under `/var/spool/cron/crontabs/username`, and reading that file directly shows the same content. Both commands let the administrator inspect the exact cron schedule and commands for that user.

Answer

crontab -e -u username

Answer

systemctl status cron

Answer

grep username /etc/crontab