LPIC-2 Linux Kernel and System Startup Practice Test 4 — 15 Questions

Question 1

Which TWO of the following commands are used to load a kernel module manually at runtime? (Choose two.)

Accepted Answer

modprobe. Both `modprobe` and `insmod` are standard Linux commands for manually loading kernel modules at runtime. `modprobe` is preferred because it automatically resolves and loads module dependencies, while `insmod` inserts a single module file directly without dependency resolution.

Answer

loadmod

Answer

depmod

Answer

modload

Question 2

Refer to the exhibit. A system administrator has configured the above in /etc/default/grub. After running update-grub, what will be the boot menu behavior?

Accepted Answer

The menu will be displayed for 10 seconds, then the default entry boots automatically.. The configuration shown in /etc/default/grub includes GRUB_TIMEOUT=10 and GRUB_TIMEOUT_STYLE=menu (or the default style if unset). After running update-grub, the boot menu will be displayed for 10 seconds, and then the default entry (set by GRUB_DEFAULT) will boot automatically. This is the standard behavior when GRUB_TIMEOUT is set to a positive integer and the timeout style is 'menu'.

Answer

The boot menu will be hidden for 0 seconds (i.e., not hidden), and the default entry boots immediately.

Answer

The menu will be displayed but with no timeout; it will wait indefinitely for user input.

Answer

The boot menu will be hidden unless Shift is pressed, and the default entry will boot after 10 seconds.

Question 3

Refer to the exhibit. Which kernel version will be booted by default when using a standard GRUB2 configuration that uses the symlinks vmlinuz and initrd.img?

Accepted Answer

5.10.0-9-amd64. In a standard GRUB2 configuration, the symlinks `vmlinuz` and `initrd.img` point to the latest installed kernel version. When GRUB2 generates its boot menu using `update-grub` (or `grub-mkconfig`), it reads these symlinks to create the default boot entry. Therefore, the default booted kernel is the one pointed to by these symlinks, which in this case is 5.10.0-9-amd64.

Answer

Depends on GRUB_DEFAULT setting, but if not set, it will boot the highest versioned kernel

Answer

It will prompt to choose between the two kernels

Answer

5.10.0-8-amd64

Question 4

Refer to the exhibit. What is the root filesystem device as specified in the kernel command line?

Accepted Answer

/dev/sda2. The kernel command line includes the parameter `root=/dev/sda2`, which explicitly specifies the root filesystem device as `/dev/sda2`. This is the standard way to indicate the partition where the root filesystem is mounted during boot, making option D correct.

Answer

Could not be determined

Answer

/dev/sda1

Answer

/dev/sda3

Question 5

A system administrator is troubleshooting a hardware issue that occurs during boot. To monitor the kernel messages in real-time, which command should be run?

Accepted Answer

dmesg -w. `dmesg -w` (or `dmesg --follow`) provides real-time monitoring of kernel ring buffer messages, which is essential for troubleshooting hardware issues during boot. The `-w` flag waits for new messages and prints them as they appear, similar to `tail -f`, but specifically for kernel messages. This command directly accesses the kernel ring buffer via `/dev/kmsg`, ensuring you see hardware-related errors, driver messages, and device initialization logs as they occur.

Answer

journalctl -f

Answer

tail -f /var/log/kern.log

Answer

less /var/log/messages

Question 6

A developer compiled a custom kernel, installed it, but the system hangs before init starts. The previous kernel works. Which step was most likely missed?

Accepted Answer

Not rebuilding initramfs. When a custom kernel is compiled and installed, the initramfs must be rebuilt to include the necessary kernel modules for mounting the root filesystem at boot. If the initramfs is not regenerated, the kernel may lack critical drivers (e.g., for storage controllers or filesystems), causing the system to hang before init starts because it cannot access the root device. The previous kernel works because its initramfs was built with the correct modules for that kernel version.

Answer

Not updating GRUB configuration

Answer

Not running depmod

Answer

Not setting the correct root filesystem

Question 7

An administrator wants to limit the size of the kernel ring buffer to prevent memory overflow. Which kernel boot parameter should be used?

Accepted Answer

log_buf_len. `log_buf_len` is the kernel boot parameter that explicitly sets the size of the kernel ring buffer (dmesg buffer). By specifying a value (e.g., `log_buf_len=4M`), the administrator can increase or limit the buffer size to prevent memory overflow when a large volume of kernel messages is generated.

Answer

log_size

Answer

kernel.log.size

Answer

dmesg_size

Question 8

A server with multiple network cards needs a specific kernel module loaded before network configuration. Where should loading be configured for early boot?

Accepted Answer

/etc/modules-load.d/. Systemd-based systems use /etc/modules-load.d/ to specify kernel modules that must be loaded early in the boot process, before network configuration. Files in this directory are processed by systemd-modules-load.service, which runs before network services, ensuring the module is available when interfaces are brought up.

Answer

/boot/grub/grub.cfg

Answer

/etc/modprobe.d/

Answer

/etc/sysconfig/modules/

Question 9

A kernel module has been recompiled. Which command updates the module dependency information?

Accepted Answer

depmod. The `depmod` command is used to generate a list of module dependencies, stored in the modules.dep file, based on the symbols exported by each kernel module. After recompiling a module, this file becomes outdated, and running `depmod -a` (or simply `depmod`) rebuilds the dependency information so that tools like `modprobe` can correctly load modules and their prerequisites.

Answer

modprobe

Answer

insmod

Answer

modinfo

Question 10

Which sysctl parameter controls the system's behavior when a kernel oops occurs (e.g., automatically reboot)?

Accepted Answer

kernel.panic_on_oops. The `kernel.panic_on_oops` sysctl parameter controls the system's behavior when a kernel oops occurs. Setting it to 1 causes the kernel to panic on an oops, and if `kernel.panic` is also set to a positive value (e.g., seconds before reboot), the system will automatically reboot after the panic. This is the correct parameter for triggering a reboot on an oops.

Answer

vm.panic_on_oom

Answer

kernel.unknown_nmi_panic

Answer

kernel.oops

Question 11

During boot, the system displays 'unable to mount root fs on unknown-block'. What is the most likely cause?

Accepted Answer

Missing filesystem driver in initramfs. The error 'unable to mount root fs on unknown-block' indicates that the kernel cannot find a driver for the filesystem or block device containing the root filesystem. This typically occurs when the initramfs lacks the necessary kernel module (e.g., ext4, xfs, or a storage controller driver like ahci or nvme) to access the root device. The initramfs is responsible for loading essential drivers before the kernel mounts the real root filesystem; if the driver is missing, the mount fails.

Answer

Corrupted init binary

Answer

Wrong block device order

Answer

Incorrect root= parameter

Question 12

To list all currently loaded kernel modules, which command is used?

Accepted Answer

lsmod. The correct command to list all currently loaded kernel modules is `lsmod`. It reads the `/proc/modules` file and displays the module name, size, used count, and a list of dependent modules. This is the standard and most direct method on Linux systems.

Answer

kmod -l

Answer

modlist

Answer

modules_loaded

Question 13

An administrator needs to ensure a kernel module is never loaded, even if requested. Which file should be used?

Accepted Answer

/etc/modprobe.d/blacklist.conf. The standard mechanism to prevent a kernel module from loading is to add a `blacklist` directive in a file under `/etc/modprobe.d/`, typically named `blacklist.conf`. The `modprobe` utility reads all `.conf` files in this directory, and a `blacklist <module_name>` entry ensures the module is never automatically loaded or loaded via `modprobe`, even if explicitly requested.

Answer

/etc/modprobe.d/deny.conf

Answer

/lib/modprobe.d/blacklist.conf

Answer

/etc/modules-load.d/blacklist.conf

Question 14

Which TWO commands can be used to rebuild the initramfs on modern Linux systems? (Choose two.)

Accepted Answer

dracut -f. `dracut -f` forces the regeneration of the initramfs on modern Red Hat–based distributions (e.g., RHEL, CentOS, Fedora). Option C is correct because `update-initramfs -u` updates the initramfs on Debian/Ubuntu systems by rebuilding the current kernel's initramfs image. Both commands are the standard tools for rebuilding the initial RAM filesystem on their respective distributions.

Answer

mkinitrd

Answer

grub-mkconfig

Answer

mkinitramfs

Question 15

Which THREE kernel boot parameters can be added to the GRUB command line to enable verbose debug output during boot? (Choose three.)

Accepted Answer

debug. The `debug` kernel boot parameter enables verbose debug output from the kernel during boot, printing extensive diagnostic messages. It is a valid parameter that can be added to the GRUB command line to increase verbosity for troubleshooting.

Answer

verbose

Answer

quiet