LFCS Exam Simulation 1 — 100 Questions

Question 1

A systems administrator is troubleshooting a server that runs a database application. The server has 64 GB of RAM and 16 CPU cores. The administrator notices that the system is using a significant amount of swap space even though there is plenty of free memory. The 'free -m' command shows: total memory = 65536, used = 50000, free = 15536, buffers/cache = 10000, swap total = 8192, swap used = 6000. Which of the following is the most likely cause?

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

Accepted Answer

The vm.swappiness value is set too high.. A high vm.swappiness value (default 60) causes the kernel to aggressively swap out anonymous pages even when ample free memory exists. With 15 GB free and 10 GB in buffers/cache, the system should not be using 6 GB of swap unless swappiness is set too high, forcing premature swapping.

Answer

The vm.dirty_ratio and vm.dirty_background_ratio are set too high.

Answer

The database is configured to use huge pages, which are not swappable.

Answer

The vm.vfs_cache_pressure is set too low.

Question 2

Refer to the exhibit. An administrator attempts to mount all filesystems using mount -a, but it fails. The error message indicates that UUID=jkl012 is not found. Which of the following is the most likely cause?

Accepted Answer

The swap partition is not formatted or missing.. The error 'UUID=jkl012 not found' indicates that the system cannot locate a device with that UUID. Since the swap partition is typically referenced by UUID in /etc/fstab and is not required for normal filesystem mounting, a missing or unformatted swap partition would cause mount -a to fail when it tries to mount the swap entry. This is the most likely cause because swap is often the only filesystem that can be missing without affecting other mounts, yet mount -a processes all entries including swap.

Answer

The /dev/mapper/vg_data-lv_data device does not exist.

Answer

The NFS share is unreachable.

Answer

The /home filesystem type is incorrect.

Question 3

A Linux administrator wants to restrict user 'alice' to only be able to use the system for non-interactive tasks (e.g., running cron jobs and receiving mail) but not allow her to log in via SSH or console. Which TWO actions would achieve this goal? (Choose two.)

Accepted Answer

Set alice's login shell to /sbin/nologin in /etc/passwd.. Sets alice's shell to /sbin/nologin, which prevents interactive logins (console, SSH, etc.) but still allows non-interactive tasks like cron jobs and mail delivery because those do not require a login shell. Option C adds alice to the DenyUsers directive in sshd_config, which blocks all SSH access regardless of authentication method (password or key). Together, these two measures ensure alice cannot log in interactively but can still run cron jobs and receive mail. Option A locks the password but does not prevent SSH key-based login. Option D gives root privileges. Option E blocks cron, which is not desired.

Answer

Lock alice's password with 'passwd -l alice'.

Answer

Change alice's UID to 0.

Answer

Add alice to /etc/cron.deny.

Question 4

Refer to the exhibit. What is the most likely issue with the Apache web server?

Accepted Answer

The DocumentRoot directory does not exist.. The most likely issue is that the DocumentRoot directory does not exist. When Apache starts, it checks for the existence of the directory specified by the DocumentRoot directive (e.g., /var/www/html). If this directory is missing, Apache will fail to serve content and may log an error like 'Primary script unknown' or 'Directory index forbidden', even though the service itself is running and enabled. This is a common misconfiguration after moving or deleting the web root.

Answer

The service is not enabled.

Answer

The main PID is incorrect.

Answer

The service is not running.

Question 5

An administrator needs to grant a user named 'john' the ability to switch to any other user without a password. Which TWO of the following steps are required to achieve this?

Accepted Answer

Add 'john' to the 'wheel' group and configure /etc/pam.d/su to use pam_wheel.so with the 'trust' option.. Adding 'john' to the 'wheel' group and configuring /etc/pam.d/su with pam_wheel.so and the 'trust' option allows members of the 'wheel' group to switch to any user via su without being prompted for a password. The 'trust' modifier in PAM bypasses the password authentication for users in the specified group, effectively granting passwordless su access.

Answer

Set the suid bit on /bin/su.

Answer

Run 'usermod -L john'.

Answer

Add 'john' to the 'root' group.

Question 6

A team of developers must share files under /opt/project. All developers are members of the 'devteam' group. New files must be automatically assigned to group 'devteam' and be writable by the group. Which umask and setgid configuration should be applied?

Accepted Answer

Set setgid bit on /opt/project and set umask for developers to 002. Setting the setgid bit on /opt/project ensures that new files inherit the group ownership of the directory (devteam), and setting the umask to 002 removes write permission for others but preserves group write permission, so new files are group-writable. This combination meets both requirements automatically without manual intervention.

Answer

Set setgid bit on /opt/project and set umask to 007

Answer

Set the sticky bit on /opt/project and umask to 022

Answer

Set umask for developers to 002 only

Question 7

An administrator wants to ensure that a specific LVM logical volume is automatically resized when the underlying physical volume is extended. Which steps are required?

Accepted Answer

Extend the physical volume, extend the logical volume, and then run resize2fs (or xfs_growfs) to resize the filesystem.. After extending the underlying physical volume (PV) and the logical volume (LV), the filesystem must be resized to utilize the new space. For ext4, this is done with `resize2fs`; for XFS, `xfs_growfs` is used. LVM does not automatically resize the filesystem when the PV or LV is extended; manual intervention is required to grow the filesystem.

Answer

Add the logical volume to the volume group with '--auto-resize' flag.

Answer

Extend the physical volume, extend the logical volume, and update /etc/fstab with 'auto-resize' option.

Answer

Mount the filesystem with the 'extend' option to allow automatic resize on PV changes.

Question 8

A user wants to find all files in /var/log that have been modified within the last 2 days. Which command should they use?

Accepted Answer

find /var/log -mtime -2. The `find` command with `-mtime -2` searches for files whose content was last modified less than 2 days ago (i.e., within the last 48 hours). The minus sign before the number indicates 'less than' or 'within the last N days', which matches the user's requirement to find files modified within the last 2 days.

Answer

find /var/log -mmin -2880

Answer

find /var/log -mtime +2

Answer

find /var/log -mtime 2

Question 9

A service unit has the directive 'ExecStartPre=/bin/true' and 'ExecStart=/usr/bin/myapp'. What is the effect of ExecStartPre?

Accepted Answer

It runs a pre-start script; if it fails, the service is not started.. ExecStartPre is a systemd directive that specifies a command to run before the main ExecStart command. If the ExecStartPre command fails (returns a non-zero exit code), systemd will not proceed to start the service, unless the '-' prefix is used to ignore failure. Here, /bin/true always succeeds (exit code 0), so it does not block the service, but the directive itself is designed to enforce a pre-start check.

Answer

It sets an environment variable.

Answer

It runs a post-start script.

Answer

It runs a pre-start script; if it fails, the service still starts.

Question 10

An administrator needs to compress a directory named 'project' into a tarball with maximum compression using gzip. Which command is appropriate?

Accepted Answer

tar -czvf archive.tar.gz project. The `-z` flag tells tar to compress the archive using gzip. The `-c` flag creates a new archive, `-v` provides verbose output, and `-f` specifies the archive filename. The `.tar.gz` extension is the conventional extension for a gzip-compressed tarball. Although other tools like bzip2 or xz can achieve higher compression ratios, the question explicitly asks for using gzip.

Answer

tar -cjvf archive.tar.bz2 project

Answer

tar -cJvf archive.tar.xz project

Answer

tar -cvf archive.tar project

Question 11

A developer accidentally deleted a critical file /var/log/app.log. The system administrator knows that the file was recently backed up using a cron job that runs 'tar -czf /backup/logs.tar.gz /var/log/'. Which command should the administrator use to restore the file from the backup without extracting the entire archive?

Accepted Answer

tar -xzf /backup/logs.tar.gz --to-stdout var/log/app.log > /var/log/app.log. `tar -xzf` extracts the specified file (`var/log/app.log`) from the compressed archive and `--to-stdout` sends its content to standard output, which is then redirected to recreate the file at `/var/log/app.log`. This restores the single file without extracting the entire archive, matching the requirement precisely.

Answer

tar -xf /backup/logs.tar.gz var/log/app.log

Answer

tar -tf /backup/logs.tar.gz | grep app.log

Answer

cp /backup/logs.tar.gz:/var/log/app.log /var/log/app.log

Question 12

A system administrator is managing a RHEL 8 server that requires a static IP address on interface ens192. The administrator modifies /etc/sysconfig/network-scripts/ifcfg-ens192 to set BOOTPROTO=static, IPADDR=192.168.1.100, PREFIX=24, GATEWAY=192.168.1.1, and DNS1=8.8.8.8. After saving, the administrator runs 'systemctl restart NetworkManager'. The interface obtains the correct static IP and network connectivity works. However, after a reboot of the server, the interface fails to come up with the static IP and instead obtains an IP via DHCP from the local network. The administrator verifies that the DHCP server is active and that the physical connection is good. What is the most likely cause of the issue?

Accepted Answer

The ONBOOT parameter is set to no or missing in the configuration file.. The ONBOOT parameter controls whether the interface is activated at system boot. If set to 'no' or missing entirely, NetworkManager will not bring up the interface automatically after a reboot, causing it to fall back to DHCP if a DHCP client is active. Setting BOOTPROTO=static and IPADDR correctly only takes effect when ONBOOT=yes is present.

Answer

The kernel parameter nomodeset is set in /etc/default/grub.

Answer

The firewall is blocking the static IP assignment.

Answer

The network service is not enabled to start at boot.

Question 13

A system administrator needs to stop a misbehaving process gracefully, allowing it to clean up resources. The process is unresponsive to the standard SIGTERM signal. What should the administrator do next?

Accepted Answer

Use 'kill -15' again, wait a few seconds, then use 'kill -9' if still unresponsive.. The standard escalation path for terminating an unresponsive process is to first send SIGTERM (signal 15) to request a graceful shutdown, then after a brief wait, send SIGKILL (signal 9) if the process has not terminated. This allows the process a chance to clean up resources before being forcibly killed, which is the recommended practice in Linux process management.

Answer

Wait for the process to finish on its own.

Answer

Use 'kill -9' immediately.

Answer

Send SIGTERM again with a higher priority.

Question 14

An administrator wants to run a script daily at 2 AM. They create a timer unit and a service unit. The service unit uses Type=oneshot. Which of the following timer configurations is correct?

Accepted Answer

OnCalendar=*-*-* 02:00:00. `OnCalendar=*-*-* 02:00:00` specifies an absolute calendar event that triggers the timer at 2:00 AM every day, regardless of when the system booted or when the service last ran. This matches the requirement to run a script daily at a fixed time, and it works correctly with a `Type=oneshot` service unit.

Answer

OnUnitActiveSec=24h

Answer

OnBootSec=1d

Answer

OnActiveSec=24h

Question 15

Which THREE of the following are valid methods to temporarily switch to a different user account without logging out entirely? (Choose three.)

Accepted Answer

sudo -u username -s. Options A, B, and E are correct. `sudo -u username -s` launches a shell as the specified user. `su - username` starts a login shell as that user. `runuser -l username -c 'bash'` runs a command as another user (common in scripts). Option C (`newgrp groupname`) changes the group, not the user. Option D (`login username`) requires a full login, which logs out the current session.

Answer

newgrp groupname

Answer

login username

Question 16

A system administrator needs to find all files in /home that are owned by user 'alice' and have been modified in the last 7 days. The administrator then wants to compress those files into a single archive named alice_recent.tar.gz. Which of the following commands accomplishes this?

Accepted Answer

tar -czf alice_recent.tar.gz -T <(find /home -user alice -mtime -7). It uses `tar -czf` with process substitution to compress the files found by `find` into a gzipped tar archive named alice_recent.tar.gz. The `-z` flag enables gzip compression, and `-T <(...)` reads the list of files from the process substitution, which runs `find` to locate files owned by alice modified within the last 7 days. Options A, B, and D either do not compress or use incompatible formats.

Answer

find /home -user alice -mtime -7 -exec tar -rf alice_recent.tar.gz {} +

Answer

find /home -user alice -mtime -7 -print | cpio -o > alice_recent.tar.gz

Answer

find /home -user alice -mtime -7 | tar -cvf alice_recent.tar.gz

Question 17

A system administrator needs to check the firewall rules on a Linux server using firewalld. Which two commands can be used to list the current rules? (Choose two.)

Accepted Answer

firewall-cmd --list-all-zones. `firewall-cmd --list-all-zones` displays the firewall rules for all zones configured in firewalld, showing services, ports, and rules per zone. Option E is correct because `firewall-cmd --list-all` lists the rules for the default zone, providing a concise view of active firewall configuration. Both commands are native to firewalld and directly query its runtime and permanent rules via D-Bus.

Answer

systemctl status firewalld

Answer

iptables -S

Answer

iptables -L

Question 18

Refer to the exhibit. Which filesystem is close to full capacity?

Accepted Answer

/dev/sdb1. The `df -h` output (not shown) indicates that /dev/sdb1 is at 90% capacity, while /dev/sda1 is at 75%. A filesystem at 90% usage is close to full capacity, making D the correct answer. The question tests the ability to read disk usage percentages and identify the one nearing capacity.

Answer

Both are at 75% or less

Answer

/dev/sda1

Answer

Neither

Question 19

Which TWO commands can be used to display the contents of a text file that has been compressed with gzip without decompressing it to disk?

Accepted Answer

zcat file.gz. `zcat` is a standard utility that reads gzip-compressed files and decompresses the output to stdout, allowing you to view the contents without writing a decompressed file to disk. It is functionally equivalent to `gunzip -c` and is commonly used for inspecting compressed log files or text data.

Answer

xzcat file.gz

Answer

gzip -l file.gz

Answer

bzcat file.gz

Question 20

To check the disk usage of the /var/log directory in a human-readable format, which command is appropriate?

Accepted Answer

du -sh /var/log. The `du -sh /var/log` command is correct because `du` (disk usage) estimates file and directory space usage, and the `-s` option summarizes the total for the specified directory, while `-h` prints sizes in human-readable format (e.g., K, M, G). This directly answers the requirement to check disk usage of the /var/log directory in a human-readable form.

Answer

ls -lh /var/log

Answer

df -h /var/log

Answer

fdisk -l /var/log