LFCS Practice Test 18 — 15 Questions

Question 1

An administrator needs to view a list of users who have logged in recently. Which command provides this information?

Accepted Answer

last. The `last` command reads the `/var/log/wtmp` file to display a list of all users who have logged in and out, including recent login sessions. This makes it the correct choice for viewing a history of recent logins, as it provides timestamps, duration, and originating host information.

Answer

users

Answer

who

Answer

finger

Question 2

Which THREE conditions must be met for a Linux system to function as a router between two networks?

Accepted Answer

Each interface has an IP address in the respective subnet. Each interface must have an IP address in its respective subnet for the Linux system to receive packets from that network and forward them to the other. Without an IP address in the subnet, the interface cannot participate in ARP resolution or routing decisions for that network.

Answer

Both interfaces have the same MAC address

Answer

The system is configured as the default gateway for both networks

Question 3

A Linux administrator needs to temporarily stop a service named 'httpd' without disabling it from starting automatically on subsequent boots. Which command should be used?

Accepted Answer

systemctl stop httpd. The `systemctl stop httpd` command sends a SIGTERM signal to the main process of the httpd service, causing it to stop immediately. This action does not modify the service's enablement state, so the service will still start automatically on subsequent boots if it is enabled. This is the correct way to temporarily stop a service without altering its boot-time behavior.

Answer

systemctl mask httpd

Answer

systemctl disable httpd

Answer

systemctl kill httpd

Question 4

Which of the following commands can be used to display the total, used, and available space for all mounted ext4 filesystems?

Accepted Answer

df -hT. The `df -hT` command displays disk space usage for all mounted filesystems, with the `-h` flag providing human-readable sizes (e.g., GB, MB) and the `-T` flag showing the filesystem type (e.g., ext4). This directly meets the requirement to show total, used, and available space for all mounted ext4 filesystems.

Answer

lsblk

Answer

fdisk -l

Answer

tune2fs -l /dev/sda1

Question 5

Which TWO commands can be used to mount a filesystem on /dev/sdb1 to /mnt/data?

Accepted Answer

mount /dev/sdb1 /mnt/data. Option B is correct because the standard mount syntax is `mount `, so `mount /dev/sdb1 /mnt/data` mounts the block device /dev/sdb1 onto the existing directory /mnt/data. Option C is also correct because adding `-t ext4` explicitly specifies the filesystem type, and the device-then-mountpoint order remains valid, so `mount -t ext4 /dev/sdb1 /mnt/data` successfully mounts the ext4 filesystem. Option A is wrong because it reverses the arguments, treating /mnt/data as the device and /dev/sdb1 as the mountpoint. Option D is wrong because `-o loop` is used to mount a regular file as a loopback device, not a real block device like /dev/sdb1. Option E is wrong because it combines an unnecessary `-t auto` with `-o loop`, which is inappropriate for mounting a physical partition.

Answer

mount /mnt/data /dev/sdb1

Answer

mount -o loop /dev/sdb1 /mnt/data

Answer

mount -t auto /dev/sdb1 /mnt/data -o loop

Question 6

A storage administrator is troubleshooting a system where a new SCSI disk is detected by the kernel but not visible in /dev/disk/by-id/. What is the most likely cause?

Accepted Answer

The udev daemon has not processed the device yet; run 'udevadm trigger' to generate links.. When a new SCSI disk is detected by the kernel, the kernel creates the device node (e.g., /dev/sdb), but the symbolic links under /dev/disk/by-id/ are generated by udev based on the device's WWID or other identifiers. If udev has not yet processed the uevent for the new disk, those persistent by-id links will not exist. Running 'udevadm trigger' forces udev to reprocess all pending or missed uevents, which creates the missing links.

Answer

The device mapper target is not set for the disk.

Answer

The disk does not have a valid partition table.

Answer

The scsi_mod kernel module is not loaded.

Question 7

Which TWO commands can be used to check the status of the sshd service on a system using systemd?

Accepted Answer

systemctl is-active sshd. `systemctl is-active sshd` directly queries systemd to report whether the sshd service is currently in an active (running) state, returning a simple exit code and text output (e.g., 'active' or 'inactive'). Option E is correct because `systemctl status sshd` provides a comprehensive view of the service's current state, including whether it is active, its PID, recent log entries, and cgroup details, making it a standard command for checking service health on systemd-based systems.

Answer

systemctl list-units --type=service

Answer

systemctl is-enabled sshd

Answer

systemctl cat sshd

Question 8

An administrator must change the ownership of /srv/project and every file and directory beneath it to user alice and group devs, without altering permissions. Which command should be used?

Accepted Answer

chown -R alice:devs /srv/project. Changing both owner and group recursively is the job of chown with the -R flag and the user:group syntax. This updates ownership metadata on every file and directory under the target path while leaving permission bits intact. chmod, usermod, and chgrp each address different attributes and cannot fulfill the combined owner-and-group requirement.

Answer

chmod -R alice:devs /srv/project

Answer

chgrp -R alice:devs /srv/project

Answer

usermod -R alice:devs /srv/project

Question 9

A user reports that a background process (PID 3456) is consuming 95% of CPU and causing system slowness. The process name is 'crypto-miner'. The administrator needs to immediately stop this process and ensure it does not restart. Which set of commands should the administrator execute?

Accepted Answer

kill -9 3456, then locate the cron job or systemd service that starts it, and disable/remove it.. It addresses both immediate termination and persistence removal. The SIGKILL signal (kill -9) immediately terminates the process, and disabling the cron job or systemd service prevents automatic restart, which is critical for a malicious or unwanted process like 'crypto-miner'.

Answer

renice -n 19 -p 3456 and let it run with lower priority.

Answer

kill -9 3456 and then notify the user.

Answer

kill -15 3456 and hope it terminates.

Question 10

Match each file system type to its typical use case.

Accepted Answer

ext4: General-purpose file system for Linux distributions, widely used on desktops and servers.. Common file systems in Linux include ext4 for general use, XFS for high-performance and large files, and Btrfs for advanced features like snapshots. Swapping definitions is a common error.

Answer

ext4: High-performance file system suitable for large files and parallel I/O, often used in enterprise storage.

Answer

XFS: Modern file system with snapshot and compression capabilities, designed for scalability and fault tolerance.

Question 11

Order the steps to configure a static IP address on a CentOS/RHEL 7 system using ifcfg files.

Accepted Answer

Edit the ifcfg file, then restart the network service, then verify the configuration.. Static IP configuration requires editing the ifcfg file, restarting network, and verification.

Answer

Restart the network service, then edit the ifcfg file, then verify the configuration.

Answer

Edit the ifcfg file, then verify the configuration, then restart the network service.

Answer

Verify the configuration, then edit the ifcfg file, then restart the network service.

Question 12

A company has a server with two network interfaces: eth0 (192.168.1.10/24, gateway 192.168.1.1) and eth1 (10.0.0.10/24, gateway 10.0.0.1). The server needs to reach a remote network 172.16.0.0/16 via a VPN tunnel that terminates at 10.0.0.5 on eth1. Which command should be used to add a route for this traffic?

Accepted Answer

ip route add 172.16.0.0/16 via 10.0.0.5 dev eth1. The VPN tunnel endpoint is at 10.0.0.5 on the eth1 network, so traffic to 172.16.0.0/16 must be forwarded via that next-hop IP address using the eth1 interface. The `ip route add` command with `via 10.0.0.5 dev eth1` explicitly sets the gateway and egress interface, ensuring packets are sent through the VPN tunnel.

Answer

ip route add 172.16.0.0/16 via 10.0.0.5 dev eth0

Answer

ip route add 172.16.0.0/16 via 192.168.1.1 dev eth0

Answer

ip route add 172.16.0.0/16 dev eth1

Question 13

You are managing a Linux server that hosts a shared project directory /projects/alpha, owned by the group 'alpha' (GID 2001). The directory has permissions 2770 (setgid, rwx for owner and group, no access for others). User 'jane' (UID 1501) has a primary group 'staff' (GID 1001) and is not in the 'alpha' group. She reports being unable to list or modify files in /projects/alpha. You need to give her access as a member of the 'alpha' group without changing her primary group. Which command sequence should you use?

Accepted Answer

usermod -aG alpha jane. The command `usermod -aG alpha jane` appends jane to the supplementary group 'alpha' without altering her primary group 'staff'. Because /projects/alpha is group-owned by alpha with 2770 permissions, group membership grants rwx access, and the setgid bit ensures new files inherit the alpha group. This satisfies the requirement of granting access without changing her primary group.

Answer

usermod -aG alpha jane; usermod -G '' jane; usermod -aG alpha jane

Answer

usermod -g alpha jane

Answer

usermod -G alpha jane

Question 14

A network administrator needs to block all incoming SSH traffic (port 22) from the 192.168.2.0/24 subnet. Which iptables command accomplishes this?

Accepted Answer

iptables -A INPUT -s 192.168.2.0/24 -p tcp --dport 22 -j DROP. It appends a rule to the INPUT chain that matches packets originating from the 192.168.2.0/24 subnet (-s 192.168.2.0/24) using TCP protocol with destination port 22 (--dport 22), and then drops them (-j DROP). This precisely blocks all incoming SSH traffic from that subnet while leaving other traffic unaffected.

Answer

iptables -A INPUT -d 192.168.2.0/24 -p tcp --dport 22 -j DROP

Answer

iptables -A OUTPUT -d 192.168.2.0/24 -p tcp --sport 22 -j DROP

Answer

iptables -A INPUT -s 192.168.2.0/24 -j DROP

Question 15

Which two commands can be used to set password expiration policies for a user?

Accepted Answer

passwd. The `passwd` command (option B) can set password expiration policies for a user via options such as `-e` (expire immediately), `-n` (minimum days), `-x` (maximum days), `-w` (warning days), and `-i` (inactive days), e.g., `passwd -x 90 -n 7 -w 14 user`. The `chage` command (option C) is specifically designed to modify password aging information in `/etc/shadow`, using flags like `-M` (max days), `-m` (min days), `-W` (warn days), `-I` (inactive days), and `-E` (account expiration date), e.g., `chage -M 90 -W 14 user`. The other options do not belong: `usermod` (A) manages account properties like groups, shell, and home directory but does not set password aging fields; `expiry` (D) is not a standard Linux command for this purpose; and `pwconv` (E) creates or updates `/etc/shadow` from `/etc/passwd` rather than setting expiration policies.

Answer

usermod

Answer

expiry

Answer

pwconv