LPIC-1 Hard Questions — 25 Difficult Questions

Question 1

A user 'jdoe' already exists. The administrator needs to add 'jdoe' to the 'staff' and 'admin' groups without changing other group memberships. Which command accomplishes this?

Accepted Answer

usermod -a -G staff,admin jdoe. The `usermod -a -G` command appends the user 'jdoe' to the supplementary groups 'staff' and 'admin' without altering existing group memberships. The `-a` (append) flag is essential; without it, `-G` would replace all current supplementary groups with only those listed. This matches the requirement to add the user to new groups while preserving other group memberships.

Answer

sed -i 's/^staff:.*/&jdoe/' /etc/group

Answer

usermod -G staff,admin jdoe

Answer

useradd -G staff,admin jdoe

Question 2

A disk is partitioned with GPT. The administrator wants to see the partition type GUIDs and partition UUIDs. Which command is most appropriate?

Accepted Answer

gdisk -l /dev/sda. `gdisk -l /dev/sda` is the GPT-specific partitioning tool that displays partition type GUIDs (e.g., EBD0A0A2-B9E5-4433-87C0-68B6B72699C7 for Microsoft basic data) and partition unique GUIDs (UUIDs) for each partition on a GPT disk. Unlike MBR tools, GPT stores these 128-bit identifiers in the partition table headers, and `gdisk` is designed to read and present them directly.

Answer

blkid /dev/sda

Answer

lsblk -f /dev/sda

Answer

fdisk -l /dev/sda

Question 3

Refer to the exhibit. The root filesystem is nearly full. The administrator needs to increase its size. Which steps should be performed?

Accepted Answer

Use lvextend to extend the logical volume and then resize2fs to resize the filesystem. The root filesystem is on an LVM logical volume, as indicated by the exhibit (e.g., /dev/mapper/rootvg-rootlv). To increase its size, you must first extend the logical volume using lvextend, then resize the filesystem with resize2fs. This two-step process ensures the underlying block device and the filesystem are both enlarged to utilize the newly available space.

Answer

Use parted to resize the root partition and then mount it

Answer

Use fdisk to increase the size of /dev/sda1 and then run resize2fs

Answer

Create a new filesystem on /dev/sda2 and mount it to /

Question 4

The system is unable to mount a filesystem that should be identified by UUID 1234-5678. The administrator checks /etc/fstab and finds the entry: UUID=1234-5678 /data ext4 defaults 0 2. What is the most likely cause of the mount failure?

Accepted Answer

The symlink for UUID 1234-5678 is broken.. The most likely cause is that the symbolic link for UUID 1234-5678 is broken. In Linux, UUID-based mounts in /etc/fstab rely on symlinks in /dev/disk/by-uuid/ that point to the actual block device. If the symlink is missing or points to a non-existent device (e.g., after a disk reorder or hardware change), the system cannot resolve the UUID to a device, causing the mount to fail even if the filesystem itself is intact.

Answer

The /data mount point does not exist.

Answer

The device /dev/sda1 is not formatted with ext4.

Answer

The UUID in the fstab entry is incorrect.

Question 5

A developer needs to ensure a bash script exits immediately if any command fails, and also prints each command before executing it. Which set of shell options should be used at the beginning of the script?

Accepted Answer

set -ex. `set -ex` combines two essential shell options: `-e` (errexit) causes the script to exit immediately if any command returns a non-zero exit status, and `-x` (xtrace) prints each command (after expansion) to stderr before executing it. This is the standard way to achieve both behaviors in a single line, as required by the question.

Answer

set -e

Answer

set -vx

Answer

set -ux

Question 6

Refer to the exhibit. An administrator runs 'ntpq -p' and sees the output shown. What is the most likely cause of the '16' stratum and '0.000' delay/offset?

Accepted Answer

The NTP daemon has recently started and has not yet synchronized.. The '16' stratum and '0.000' delay/offset values in the 'ntpq -p' output indicate that the NTP daemon has not yet synchronized with any time source. When ntpd starts, it initially sets the stratum to 16 (unsynchronized) and shows zero values for delay and offset until it completes the synchronization process. This is a normal transient state that resolves once the daemon successfully contacts and synchronizes with an NTP server.

Answer

The NTP service is not running.

Answer

The firewall is blocking UDP port 123.

Answer

The restrict lines are blocking all NTP queries.

Question 7

A database server on a Linux system is configured to listen on TCP port 3306. The administrator wants to restrict access to the database server to only the local network (192.168.1.0/24) using iptables. Which of the following iptables rules achieves this?

Accepted Answer

iptables -A INPUT -p tcp --dport 3306 -s 192.168.1.0/24 -j ACCEPT. It adds an INPUT chain rule that accepts TCP traffic destined for port 3306 only when the source address is within the 192.168.1.0/24 subnet. This effectively restricts incoming database connections to the local network, while all other sources are implicitly dropped by the default INPUT policy or subsequent rules.

Answer

iptables -A INPUT -p tcp --dport 3306 -d 192.168.1.0/24 -j DROP

Answer

iptables -A OUTPUT -p tcp --dport 3306 -d 192.168.1.0/24 -j ACCEPT

Answer

iptables -A OUTPUT -p tcp --sport 3306 -s 192.168.1.0/24 -j ACCEPT

Question 8

Refer to the exhibit. The administrator restarts the sshd service. What is the new main PID after restart?

Accepted Answer

It will be a new, different PID.. When the sshd service is restarted, the old process is terminated and a new process is spawned, resulting in a new main PID. The PID is a unique identifier assigned by the kernel to each process at creation time, and it is never reused immediately after termination. Therefore, the new main PID will be different from the previous one.

Answer

It remains the same.

Answer

1235

Answer

1234

Question 9

A Debian system has a broken package that was partially installed. Which command will attempt to fix dependencies and configure all unpacked but not configured packages?

Accepted Answer

dpkg --configure -a. The command `dpkg --configure -a` is the correct choice because it configures all unpacked but not yet configured packages, and also attempts to fix dependency issues by re-running the configuration scripts. This is the standard way to recover from a partially installed package on Debian systems, as it ensures all packages in the 'unpacked' or 'half-configured' state are fully processed.

Answer

dpkg -i --force-depends

Answer

apt-get autoremove

Answer

apt-get clean

Question 10

Which TWO conditions would cause the boot process to fall back to the GRUB rescue shell? (Choose two.)

Accepted Answer

The GRUB modules are not loaded from the correct path.. The GRUB rescue shell is entered when the core image cannot locate its modules, typically due to an incorrect module path. This prevents GRUB from loading its normal configuration, causing a fallback to the minimal rescue shell. Missing or corrupt grub.cfg, on the other hand, leads to the GRUB normal shell (grub>), not the rescue shell. Other issues like missing kernel, initramfs, or BIOS failure occur after GRUB or before it starts, so they do not trigger the rescue shell.

Answer

The kernel image is not found in /boot.

Answer

The BIOS cannot find a bootable device.

Answer

The initramfs is missing or corrupt.

Answer

The /boot/grub/grub.cfg file is missing or corrupt.

Question 11

Refer to the exhibit. What type of traffic is being captured?

Accepted Answer

A successful TCP three-way handshake followed by a data transfer.. The exhibit shows a TCP three-way handshake (SYN, SYN-ACK, ACK) followed by a data transfer segment (PSH, ACK). This sequence indicates a successful connection establishment and subsequent data exchange, which matches the description of a successful TCP three-way handshake followed by data transfer.

Answer

An incomplete TCP handshake.

Answer

An FTP session.

Answer

A DNS query and response.

Question 12

A server in a corporate network uses systemd-resolved for DNS. Internal hostnames (e.g., server.example.lan) fail to resolve, but external names (e.g., google.com) work. The /etc/resolv.conf is a symlink to /run/systemd/resolve/stub-resolv.conf. The administrator checks the systemd-resolved configuration and finds that the internal DNS server is listed globally, but the network interface has no specific DNS set. Which command should be used to assign the internal DNS server to the interface and fix resolution?

Accepted Answer

Run 'resolvectl dns eth0 10.0.0.1' to set the DNS server for the interface.. `resolvectl dns eth0 10.0.0.1` assigns the internal DNS server specifically to the network interface (eth0), overriding the global setting for that interface. In systemd-resolved, per-interface DNS settings take precedence over global DNS servers, so this command ensures that internal hostnames are resolved by the internal DNS server while external names continue to work via the global configuration.

Answer

Add the internal hostnames to /etc/hosts.

Answer

Restart systemd-resolved service.

Answer

Edit /etc/resolv.conf and add the internal DNS server.

Question 13

A sysadmin wants to prevent an APT package from being upgraded automatically but still allow it to be upgraded manually if needed. Which configuration method best achieves this?

Accepted Answer

Use 'apt-mark hold '. The `apt-mark hold ` command marks a package as held back, preventing it from being automatically upgraded during `apt upgrade` or `apt dist-upgrade`, while still allowing manual upgrades via `apt install ` or `apt-mark unhold`. This directly meets the requirement of blocking automatic upgrades but permitting manual intervention.

Answer

Set the package version to a non-existent version in /etc/apt/preferences

Answer

Add the package to /etc/apt/preferences with Pin-Priority: 1000

Answer

Remove the package from sources.list

Question 14

When troubleshooting a problem with a Debian package installation, an administrator wants to see which version of a package would be installed from the configured repositories. Which command displays the candidate version?

Accepted Answer

apt-cache policy package. The `apt-cache policy package` command displays the package's priority, the installed version (if any), and the candidate version (the version that would be installed by default from the configured repositories). This makes it the correct tool for determining which version will be installed from the repositories.

Answer

dpkg -l package

Answer

apt-show-versions package

Answer

apt-get -s install package

Question 15

After creating a new user with 'useradd john', the user 'john' cannot log in. What is the most likely cause?

Accepted Answer

No password has been set for the user. The `useradd` command creates a new user account but does not set a password. Without a password, the system's authentication mechanism (typically PAM) will deny login attempts, as there is no valid password hash in `/etc/shadow`. The user must have a password assigned via `passwd john` before they can authenticate.

Answer

The home directory does not exist

Answer

The user's shell is not set

Answer

The user is not in the sudoers file

Question 16

Refer to the exhibit. A system administrator finds this line in /etc/rsyslog.conf. What is the effect of this configuration?

Accepted Answer

All syslog messages are forwarded via UDP to the server at 192.168.1.100 on port 514.. The line `*.* @192.168.1.100:514` in rsyslog.conf uses the `@` symbol to indicate UDP forwarding. The `*.*` selector means all facilities and all priorities, so every syslog message is forwarded via UDP to the server at 192.168.1.100 on port 514. This is a standard rsyslog syntax for remote logging.

Answer

Only messages with facility *.info are forwarded.

Answer

All syslog messages are forwarded via TCP to the server.

Answer

Only authentication-related messages are forwarded.

Question 17

Which THREE of the following are valid symbolic mode expressions for the chmod command?

Accepted Answer

u+x. Option A (u+x) is a valid symbolic mode because it specifies the user class 'u' and adds (+) the execute permission, which is standard chmod symbolic syntax. Option C (a+rwx) is valid because 'a' represents all three permission classes (user, group, and other) and +rwx grants read, write, and execute to each. Option E (g-w) is valid because it targets the group class 'g' and removes (-) the write permission. Option B (755) is not a symbolic mode but an octal (numeric) mode, which uses digits rather than letters and operators. Option D (c+r) is invalid because 'c' is not a recognized permission class in chmod; the valid classes are u, g, o, and a.

Answer

755

Answer

c+r

Question 18

A server has two disk drives: /dev/sda (SSD) and /dev/sdb (HDD). The administrator wants to place frequently accessed files on the SSD for performance. Which approach best achieves this using Linux filesystem features?

Accepted Answer

Create separate LVM logical volumes on each disk and mount them at different mount points.. LVM allows the administrator to create separate logical volumes on each physical disk (/dev/sda and /dev/sdb) and mount them at distinct mount points. By placing frequently accessed files on the SSD logical volume and less critical data on the HDD logical volume, the administrator can directly control which files benefit from the SSD's faster performance without mixing data or requiring complex overlays.

Answer

Configure RAID 0 across both disks to combine speed.

Answer

Use symbolic links to redirect file access to the SSD.

Answer

Use a union mount to overlay the SSD on top of the HDD.

Question 19

Refer to the exhibit. The system administrator wants to ensure the /data filesystem is mounted only if it is available at boot time, and if not, the system should continue to boot without error. Which change should be made to the /etc/fstab entry for /data?

Accepted Answer

Add the 'nofail' option and set the last field to 0. The 'nofail' mount option tells systemd that if the filesystem fails to mount at boot, the boot process should continue without error. Setting the last field (fs_passno) to 0 disables filesystem checks, which is appropriate for a non-critical filesystem that may not be present. This combination ensures the system boots normally even if /data is unavailable.

Answer

Change the mount point to /mnt/data

Answer

Change the filesystem type to auto

Answer

Add the 'noauto' option

Question 20

A company is setting up a database server that requires high reliability and support for snapshots. The storage will be on a single large disk. Which filesystem is best suited for this requirement?

Accepted Answer

btrfs. Btrfs (B-tree filesystem) is best suited for this requirement because it natively supports snapshots, checksumming, and copy-on-write (CoW) for high reliability, all on a single disk. Unlike other Linux filesystems, btrfs provides built-in snapshot and rollback capabilities without requiring an external volume manager, making it ideal for database servers needing consistent point-in-time backups.

Answer

ext4

Answer

NTFS

Answer

XFS