LPIC-2 Linux Kernel and System Startup Practice Test 3 — 15 Questions

Question 1

A Linux server with a custom 5.15 kernel is experiencing random freezes. The administrator suspects a kernel module is causing the issue and wants to prevent it from loading at boot without permanently deleting it. The module is named 'faulty_drv'. Which method will blacklist the module so it is not loaded automatically, while still allowing manual loading with modprobe?

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

Accepted Answer

Create /etc/modprobe.d/blacklist-faulty.conf with 'blacklist faulty_drv' and run 'update-initramfs -u'.. The correct method is to add a blacklist entry in /etc/modprobe.d/ and update the initramfs. This prevents automatic loading while allowing manual modprobe. The install directive blocks all loading, adding to modules-load.d does the opposite, and editing /etc/modules is ineffective on systemd systems.

Answer

Add 'install faulty_drv /bin/false' to /etc/modprobe.d/blacklist-faulty.conf.

Answer

Edit /etc/modules and comment out the line containing 'faulty_drv'.

Answer

Run 'modprobe -r faulty_drv' and add 'faulty_drv' to /etc/modules-load.d/blacklist.conf.

Question 2

A server administrator runs `uname -r` and sees `4.19.0-14-amd64`. They want to install a newer kernel package from the distribution's repository while keeping the current working kernel available as a fallback. After installing the new kernel package, which action is required to ensure the new kernel is used on the next boot?

Accepted Answer

Run `update-grub` to regenerate the GRUB configuration with the new kernel as the default entry.. After installing a new kernel package, the bootloader must be updated to include the new kernel entry and make it the default. On Debian-based systems, `update-grub` regenerates the GRUB configuration, detecting the new kernel and setting it as the default. The old kernel remains in the menu as a fallback. Without this step, the system continues to boot the previous kernel.

Answer

Run `dracut --force` to create a new initramfs for the installed kernel.

Answer

Run `grub-install /dev/sda` to reinstall the bootloader to the MBR.

Answer

Run `update-initramfs -u -k all` to regenerate the initramfs for all kernels.

Question 3

A Linux administrator is troubleshooting a system that fails to boot after a kernel update. The system uses an initramfs. Which TWO of the following statements are true regarding the initramfs and its role in the boot process? (Choose two.)

Accepted Answer

The initramfs contains kernel modules needed to mount the root filesystem.. The initramfs is a temporary early userspace environment that contains kernel modules and scripts needed to mount the real root filesystem. It is loaded by the bootloader and passed to the kernel. It is not permanently mounted, nor is it generated by a `make initramfs` command. Custom scripts are possible but not a core truth.

Answer

The initramfs can include custom scripts to perform tasks before mounting the root filesystem.

Answer

The initramfs is permanently mounted as the root filesystem after boot.

Answer

The initramfs is generated by the `make initramfs` command during kernel compilation.

Question 4

A system administrator needs to check the current value of the kernel parameter `net.ipv4.ip_forward` at runtime. Which command will display this value?

Accepted Answer

sysctl net.ipv4.ip_forward. The `sysctl` command is used to read and modify kernel parameters at runtime. Running `sysctl net.ipv4.ip_forward` displays the current value of that parameter. While reading the corresponding file in /proc/sys also works, sysctl is the standard tool for this purpose.

Answer

cat /proc/sys/net/ipv4/ip_forward

Answer

modprobe net.ipv4.ip_forward

Answer

lsmod net.ipv4.ip_forward

Question 5

A Linux administrator needs to compile a custom kernel for a server that requires a specific network driver not enabled in the distribution kernel. The administrator has downloaded and extracted the kernel source into /usr/src/linux-5.15.0 and wants to configure it using the running kernel's configuration as a starting point, then build and install the kernel and its modules. Which TWO commands are appropriate to accomplish the configuration and build steps? (Choose two.)

Accepted Answer

make oldconfig. Reusing a running kernel configuration begins with make oldconfig, which updates the .config for the new source and prompts for new options, allowing the administrator to enable the required driver. After compiling, make modules_install installs the modules into /lib/modules for the new kernel version. Together these represent the configuration and installation phases requested. menuconfig is interactive configuration only, make dep is obsolete, and make clean only removes build artifacts.

Answer

make menuconfig

Answer

make clean

Answer

make dep

Question 6

A system administrator needs to ensure that a custom kernel module loads automatically at boot. The module is named 'my_driver' and is built for the current kernel. Which configuration file should be modified to ensure the module loads automatically?

Accepted Answer

Add a configuration file in /etc/modules-load.d/. Systemd-based Linux distributions use /etc/modules-load.d/ to specify kernel modules that should be loaded automatically at boot. Placing a configuration file (e.g., my_driver.conf) containing the module name 'my_driver' in this directory instructs systemd-modules-load.service to load the module during early boot. This is the modern, distribution-agnostic method for ensuring a custom kernel module loads automatically.

Answer

Add the insmod command in /etc/rc.local

Answer

Add the module name to /etc/modules.conf

Answer

Add a configuration file in /etc/modprobe.d/

Question 7

A server with a custom kernel fails to boot after a kernel update. The system displays a kernel panic: 'VFS: Unable to mount root fs on unknown-block(0,0)'. The root filesystem is on an LVM volume. What is the most likely cause?

Accepted Answer

The initramfs is missing LVM support.. The kernel panic 'VFS: Unable to mount root fs on unknown-block(0,0)' indicates the kernel cannot locate the root filesystem. Since the root filesystem resides on an LVM volume, the initramfs must contain LVM tools and modules to activate the volume group and logical volumes before the kernel can mount the root. If the initramfs was not rebuilt after the kernel update, it will lack LVM support, causing the boot failure.

Answer

The GRUB configuration is pointing to the wrong kernel partition.

Answer

The kernel does not have the necessary device drivers compiled in.

Answer

The root filesystem is formatted with an unsupported filesystem.

Question 8

A system administrator wants to change the default kernel boot parameters temporarily to debug a boot issue. Which step should be taken at the GRUB menu to modify kernel parameters for the next boot only?

Accepted Answer

Select the kernel entry and press 'e' to edit the boot parameters.. Pressing 'e' at the GRUB menu allows you to edit the boot parameters for the selected kernel entry temporarily. This modifies the kernel command line only for the current boot, without persisting changes to disk. After editing, pressing Ctrl+X or F10 boots the system with the modified parameters, making it ideal for debugging boot issues.

Answer

Edit /etc/default/grub and run update-grub to apply changes.

Answer

Press 'c' to enter the command line and modify parameters.

Answer

Press 'Esc' to access the advanced options menu.

Question 9

A developer has compiled a custom kernel with a new feature. The kernel modules are installed in /lib/modules/$(uname -r)/. However, when the system boots, the kernel fails to load some modules with 'Exec format error'. What is the most likely cause?

Accepted Answer

The modules were compiled against a different kernel version.. The 'Exec format error' indicates that the kernel module binary is incompatible with the running kernel. This most commonly occurs when modules are compiled against a different kernel version (e.g., different kernel source tree or configuration), as the module's vermagic string must exactly match the kernel's vermagic. The kernel's module loader checks this version magic before loading; a mismatch causes the exec format error.

Answer

The kernel configuration has disabled module loading.

Answer

The modules have incorrect file permissions.

Answer

The modules are not properly ordered in the dependency file.

Question 10

A system administrator needs to find out which kernel parameters were passed at boot time. Which command displays the kernel boot parameters?

Accepted Answer

cat /proc/cmdline. The correct command is `cat /proc/cmdline` because the Linux kernel stores the boot parameters (also known as the kernel command line) passed by the bootloader (e.g., GRUB) in the virtual file `/proc/cmdline`. Reading this file directly displays the exact parameters used during boot, such as `root=`, `quiet`, or `splash`.

Answer

dmesg

Answer

lsmod

Answer

cat /proc/version

Question 11

Which THREE factors can cause a kernel panic during boot? (Select THREE.)

Accepted Answer

Corrupted kernel image. A kernel panic during boot occurs when the kernel cannot continue initializing the system. Option B (Corrupted kernel image) is correct because if the kernel binary itself is damaged or truncated, the bootloader loads invalid code and the kernel cannot execute, triggering a panic. Option C (Hardware incompatibility) is correct because unsupported or faulty hardware (e.g., CPU features, memory, or chipset) can cause the kernel to hit an unrecoverable error during early initialization. Option E (Missing device drivers for storage controllers) is correct because if the kernel lacks the driver needed to access the root filesystem's storage controller, it cannot mount root and will panic with a 'VFS: Unable to mount root fs' error. Option A (Too many kernel modules loaded) is not a direct cause of panic; module count alone does not break boot, and modules load after the kernel is already running. Option D (Filesystem errors on the root partition) typically cause a mount failure or drop to a recovery shell rather than a kernel panic, since the kernel itself can still run and report the error.

Answer

Too many kernel modules loaded

Answer

Filesystem errors on the root partition

Question 12

A systems administrator is troubleshooting a server that fails to boot after a kernel upgrade. The boot process hangs at the stage where the kernel attempts to mount the root filesystem. Which of the following is the most likely cause?

Accepted Answer

The root= parameter in the kernel command line points to a non-existent device.. When the kernel fails to mount the root filesystem during boot, the most common cause is an incorrect or missing `root=` parameter in the kernel command line. This parameter specifies the device (e.g., `/dev/sda1` or `UUID=...`) that the kernel should mount as the root filesystem; if it points to a non-existent device, the kernel cannot proceed past the mount stage, resulting in a hang or kernel panic.

Answer

The root filesystem is formatted with an unsupported filesystem type.

Answer

The initrd image is missing from the /boot partition.

Answer

The GRUB bootloader is not installed on the MBR.

Question 13

During boot, the kernel panics with 'VFS: Unable to mount root fs on unknown-block(0,0)'. Which of the following is the most likely cause?

Accepted Answer

The kernel lacks the driver for the storage controller.. The error 'VFS: Unable to mount root fs on unknown-block(0,0)' indicates the kernel cannot find a driver for the block device containing the root filesystem. This most commonly occurs when the kernel lacks the necessary storage controller driver (e.g., for SATA, NVMe, or SCSI controllers), often because the driver was built as a module and not included in the initramfs or compiled into the kernel.

Answer

The kernel image is corrupted.

Answer

The init process is missing.

Answer

The root filesystem is formatted with an unsupported filesystem.

Question 14

Arrange the steps to configure a Linux server as an NFS client that mounts a remote export.

Accepted Answer

1. Install the nfs-common package
2. Create a mount point directory
3. Add an entry to /etc/fstab
4. Mount the remote export
5. Verify the mount. The NFS client needs the nfs-common package, a mount point, an fstab entry, then mounting and verification.

Answer

1. Install the nfs-common package
2. Add an entry to /etc/fstab
3. Create a mount point directory
4. Mount the remote export
5. Verify the mount

Answer

1. Create a mount point directory
2. Mount the remote export
3. Add an entry to /etc/fstab
4. Install the nfs-common package
5. Verify the mount

Answer

1. Add an entry to /etc/fstab
2. Create a mount point directory
3. Install the nfs-common package
4. Mount the remote export
5. Verify the mount

Question 15

Order the steps to configure a Linux system as an SSH server with key-based authentication.

Accepted Answer

Install SSH server, then configure SSH server, then generate SSH key pair, then copy public key to server, then restart SSH service and test.. Install SSH server, configure it, generate keys, copy public key, restart and test.

Answer

Generate SSH key pair, then install SSH server, then configure SSH server, then copy public key, then restart and test.

Answer

Install SSH server, then generate SSH key pair, then copy public key, then configure SSH server, then restart and test.

Answer

Install SSH server, then configure SSH server, then copy public key, then generate SSH key pair, then restart and test.