LPIC-2 Linux Kernel and System Startup Practice Test 7 — 15 Questions

Question 1

A Debian 12 server boots with a monolithic kernel that has no initramfs support for the root disk. The administrator needs to pass the parameter 'root=/dev/sdb2' to the kernel at boot time without editing GRUB configuration files permanently. Which GRUB 2 command allows a one-time kernel parameter change at the boot menu?

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

Accepted Answer

Press 'e' to edit the selected menu entry, append 'root=/dev/sdb2' to the linux line, then press Ctrl+X or F10 to boot.. The correct approach is to edit the GRUB 2 menu entry at boot time by pressing 'e', modifying the linux line to include root=/dev/sdb2, and booting with Ctrl+X or F10. This applies the parameter only for that boot, leaving the system configuration unchanged. The other methods either enter a manual command shell, use the wrong key, or attempt permanent configuration changes.

Answer

Press 'Tab' to edit the kernel command line, add 'root=/dev/sdb2', and press Enter to boot.

Answer

Press 'c' to enter the GRUB command line, then run 'linux /vmlinuz root=/dev/sdb2' followed by 'boot'.

Answer

Run 'grub-mkconfig -o /boot/grub/grub.cfg' with the new root parameter, then reboot.

Question 2

A server uses an initramfs image generated by dracut. After adding a new storage driver module, the administrator needs to ensure the module is included in the initramfs for the running kernel. Which command should be executed?

Accepted Answer

dracut -f /boot/initramfs-$(uname -r).img $(uname -r). On a dracut-based system, the initramfs is rebuilt with the dracut command. Using dracut -f with the kernel version and output path forces regeneration and includes newly added modules. Other tools like mkinitrd or update-initramfs are either legacy or distribution-specific and may not properly integrate with dracut configuration.

Answer

grub-mkconfig -o /boot/grub/grub.cfg

Answer

update-initramfs -u -k $(uname -r)

Answer

mkinitrd -f /boot/initramfs-$(uname -r).img $(uname -r)

Question 3

An administrator is diagnosing slow boot on a systemd host. The output of systemd-analyze blame shows a custom storage unit taking 42 seconds. The administrator suspects the unit is waiting on a device that appears late. Which command should the administrator use to inspect the unit's dependencies and the ordering relationships that could explain the delay?

Accepted Answer

systemd-analyze critical-chain custom-storage.service. The critical-chain subcommand of systemd-analyze is designed to trace the timing path leading to a unit, combining ordering and dependency data with actual elapsed times. It reveals which preceding units or devices delay the target, making it the most direct tool for explaining a 42-second wait. Listing dependencies or dumping properties shows relationships without timing, and journal logs may be silent during a passive wait.

Answer

systemctl list-dependencies --all custom-storage.service

Answer

systemctl show custom-storage.service

Answer

journalctl -b -u custom-storage.service

Question 4

A server uses an initramfs generated by dracut. After replacing a storage controller, the system boots but drops to the dracut emergency shell because the root device is not found. The administrator confirms the new controller's driver module exists in /lib/modules and that the device is present at boot. Which action best ensures the driver is included in the next initramfs so the root device can be mounted automatically?

Accepted Answer

Add the module name to /etc/dracut.conf.d/10-drivers.conf using add_drivers+=" modulename " and rebuild with dracut -f. dracut builds the initramfs from the running host configuration and the current root device, so a controller installed after the image was generated may be omitted. Explicitly listing the module with add_drivers in a dracut conf drop-in and regenerating with dracut -f guarantees the driver ships inside the early boot image. depmod, fstab edits, and modules-load.d entries all act too late or on unrelated mechanisms.

Answer

Edit /etc/fstab to reference the root device by UUID instead of by device path

Answer

Add the module to /etc/modules-load.d/controller.conf and reboot

Answer

Run depmod -a to regenerate module dependencies and reboot the system

Question 5

A technician needs to inspect the kernel command line that the currently running kernel received at boot on a systemd-based distribution, without rebooting. Which file should be read?

Accepted Answer

/proc/cmdline. The running kernel's exact command line is exposed through /proc/cmdline, which the kernel populates from the boot_params structure at early boot. This includes interactive GRUB edits and bootloader-injected options. Configuration files such as /etc/default/grub and grub.cfg only describe future or intended boots, and no standard /sys/kernel/boot_params exists. For live verification of kernel parameters, /proc/cmdline is the correct source.

Answer

/boot/grub/grub.cfg

Answer

/etc/default/grub

Answer

/sys/kernel/boot_params

Question 6

An administrator is hardening a server that uses an initramfs generated by dracut. The requirement is to prevent the initramfs from automatically loading a specific storage driver and to ensure the real root filesystem's modules are included. Which TWO actions achieve these goals? (Choose two.)

Accepted Answer

Add the driver name to /etc/dracut.conf.d/blacklist.conf using the omit_drivers directive and regenerate the initramfs.. dracut reads configuration from /etc/dracut.conf.d/, where omit_drivers excludes modules from the initramfs and force_drivers guarantees inclusion. Together they let an administrator block a specific storage driver while ensuring the real root filesystem's modules are present. Regenerating with dracut -f applies the changes. The other options either add drivers, rely on hostonly heuristics, or include everything, none of which meet the precise hardening requirement.

Answer

Run dracut --regenerate-all --force with the --no-hostonly flag to include all available drivers.

Answer

Set hostonly=yes in /etc/dracut.conf and rebuild so that only modules for the current root device are included.

Answer

Use the instmods command inside a dracut module script to force-include the storage driver.

Question 7

A Linux administrator needs to rebuild the initramfs for the currently running kernel on a Debian 12 system after adding a new storage driver. Which command should be used?

Accepted Answer

update-initramfs -u -k $(uname -r). The correct command for Debian 12 is update-initramfs -u -k $(uname -r). This updates the initramfs for the running kernel, incorporating the new storage driver. The other commands are specific to other distributions: dracut for Red Hat, mkinitcpio for Arch, and genkernel for Gentoo. Using them on Debian would not produce the desired result.

Answer

dracut -f --kver $(uname -r)

Answer

mkinitcpio -p linux

Answer

genkernel --initramfs

Question 8

A Linux server uses systemd and has a custom service unit that must start after the network is fully online and after a remote filesystem is mounted. Which directive in the unit file ensures the service starts only after those dependencies are met?

Accepted Answer

After=network-online.target remote-fs.target. In systemd, ordering dependencies are expressed with After= and Before=, while requirement dependencies use Requires= and Wants=. To ensure a service starts only after the network is online and remote filesystems are mounted, the After= directive must list network-online.target and remote-fs.target. This guarantees the correct startup sequence without imposing a hard requirement that could cause the service to fail if the targets are not reached.

Answer

Before=network-online.target remote-fs.target

Answer

Requires=network-online.target remote-fs.target

Answer

Wants=network-online.target remote-fs.target

Question 9

A server with a custom 5.x kernel boots but the root filesystem is mounted read-only and systemd reports that remounting to read-write failed. The kernel command line includes 'root=/dev/mapper/vg-root ro'. The administrator wants the root filesystem mounted read-write as early as possible during boot. Which change is most appropriate?

Accepted Answer

Replace 'ro' with 'rw' in the kernel command line and regenerate the bootloader configuration.. The kernel command line parameters 'ro' and 'rw' control the initial mount mode of the root filesystem. When 'ro' is present, the kernel mounts root read-only, and if no initramfs or later service remounts it read-write, systemd will report failure. Replacing 'ro' with 'rw' and regenerating the bootloader configuration makes root read-write from the earliest mount, which is the correct fix for a custom kernel without an initramfs remount step.

Answer

Add 'init=/bin/bash' to the kernel command line to get a shell and then remount manually.

Answer

Add 'systemd.unit=rescue.target' to the kernel command line so systemd remounts root read-write.

Answer

Add 'rootflags=rw' to the kernel command line in addition to the existing 'ro' parameter.

Question 10

A system administrator needs to change the default kernel that GRUB 2 boots on a UEFI-based Linux server. The system has multiple kernels installed. Which file should be edited to set the default boot entry persistently?

Accepted Answer

/etc/default/grub. The persistent way to change the default GRUB 2 boot entry is to edit /etc/default/grub, set GRUB_DEFAULT to the desired entry, and run update-grub. This regenerates grub.cfg correctly. Directly editing grub.cfg or other files is either temporary or incorrect. The EFI path is not the standard configuration file for GRUB 2 on Linux.

Answer

/etc/grub.d/40_custom

Answer

/boot/grub/grub.cfg

Answer

/boot/efi/EFI/grub/grub.cfg

Question 11

An administrator must ensure that a custom kernel module named 'acme_sensor' loads with the parameter 'poll_interval=500' automatically at every boot on a systemd server. The module is installed in /lib/modules/$(uname -r)/extra/. Which approach is correct and persistent?

Accepted Answer

Create /etc/modprobe.d/acme.conf with 'options acme_sensor poll_interval=500' and add 'acme_sensor' to /etc/modules-load.d/acme.conf.. On systemd systems, modules to load at boot are listed in /etc/modules-load.d/*.conf, and module parameters are set with options lines in /etc/modprobe.d/*.conf. This pairing ensures the module loads automatically and always uses poll_interval=500, regardless of who triggers the load. It is persistent, distribution-standard, and works with modules under /lib/modules/$(uname -r)/extra/ because modprobe searches the full module tree for the running kernel.

Answer

Run 'insmod /lib/modules/$(uname -r)/extra/acme_sensor.ko poll_interval=500' and add it to /etc/rc.local.

Answer

Use 'modprobe acme_sensor poll_interval=500' in a systemd unit of Type=oneshot enabled at multi-user.target.

Answer

Add 'acme_sensor poll_interval=500' to /etc/modules and rebuild the initramfs with dracut -f.

Question 12

A Linux server uses systemd and has a custom kernel module named `foo.ko` located in `/lib/modules/$(uname -r)/kernel/drivers/misc/`. The administrator wants to ensure that this module is loaded automatically at boot, but only after a specific hardware device is detected. Which approach is most appropriate?

Accepted Answer

Create a udev rule that matches the device and runs `modprobe foo`.. To load a module conditionally when a specific hardware device is detected, a udev rule is the correct mechanism. The rule matches the device and invokes modprobe, ensuring the module loads only when the hardware is present. This provides the necessary ordering and dependency handling, unlike unconditional loading via modules-load.d or legacy methods.

Answer

Add the module name to `/etc/modules-load.d/foo.conf`.

Answer

Add `foo` to `/etc/modprobe.d/blacklist.conf` with an alias.

Answer

Run `depmod -a` and add the module to `/etc/rc.local`.

Question 13

A system administrator needs to modify the kernel command line for a system using GRUB 2 on a BIOS-based machine. The change should persist across reboots. Which file should be edited to add the parameter `quiet splash`?

Accepted Answer

/etc/default/grub. Persistent kernel command line changes in GRUB 2 are made by editing `/etc/default/grub`, specifically the `GRUB_CMDLINE_LINUX_DEFAULT` variable for default boot entries. After editing, `update-grub` regenerates `grub.cfg`. Directly editing `grub.cfg` or other files is not persistent or appropriate.

Answer

/boot/grub2/grubenv

Answer

/etc/grub.d/40_custom

Answer

/boot/grub/grub.cfg

Question 14

A Linux server running a mainline distribution kernel has begun showing intermittent I/O errors on a SATA disk attached to an AHCI controller. The administrator suspects that a recently backported driver in the running kernel is at fault and wants to boot the system using the previous kernel version that is still installed, without modifying GRUB's default entry permanently. Which GRUB 2 feature should the administrator use at the boot menu to select the older kernel for this boot only?

Accepted Answer

At the GRUB menu, navigate to the 'Advanced options for <distro>' submenu and select the previous kernel version entry.. The Advanced options submenu in GRUB 2 exposes every installed kernel and its initramfs as separate entries. Choosing a previous kernel entry boots that kernel for the current boot only, which is ideal for testing whether a recent driver backport caused the I/O errors. Editing entries or changing the default would either alter persistent configuration or bypass the normal boot path, neither of which matches the one-time kernel selection requirement.

Answer

Press 'e' on the desired menu entry, then append 'init=/bin/bash' to the linux line and press Ctrl+X.

Answer

Press 'c' to enter the GRUB command line, then run 'linux /vmlinuz.old root=/dev/sda2' and 'boot'.

Answer

Run 'grub-set-default 1' from the running system and reboot.

Question 15

A Linux server with a custom-compiled kernel 5.10 and a matching initramfs fails to boot after the administrator added a new SCSI controller and moved the root filesystem to a disk attached to it. The kernel panics with 'VFS: Unable to mount root fs on unknown-block(0,0)'. The administrator confirms that the new controller driver was built as a module and is present in /lib/modules/5.10.0-custom/. Which action will most directly allow the initramfs to load the controller driver and mount the root filesystem?

Accepted Answer

Add the module name for the new SCSI controller to /etc/initramfs-tools/modules, then run 'update-initramfs -u -k 5.10.0-custom'.. The initramfs must contain the storage controller driver to access the root filesystem before the real root is mounted. On Debian-based systems, /etc/initramfs-tools/modules forces specific modules into the initramfs, and update-initramfs -u -k rebuilds it for that kernel. This directly addresses the missing driver that causes the VFS panic. Other actions either do not affect initramfs contents or only delay the inevitable failure.

Answer

Run 'depmod -a 5.10.0-custom' followed by 'mkinitramfs -o /boot/initrd.img-5.10.0-custom 5.10.0-custom'.

Answer

Add 'rootdelay=10' to the kernel command line in GRUB and reboot.

Answer

Run 'modprobe <controller_module>' on the running system and then reboot.