LPIC-1 System Architecture Practice Test 6 — 15 Questions

Question 1

Which command shows the amount of free and used memory in the system, including swap?

Accepted Answer

free -h. The `free -h` command displays the total, used, and free physical memory (RAM) and swap space in a human-readable format (e.g., GiB, MiB). The `-h` flag ensures output is scaled to appropriate units, making it the direct and correct tool for checking both memory and swap usage.

Answer

top

Answer

df -h

Answer

vmstat

Question 2

A system administrator needs to see the boot messages recorded by systemd-journald from the current boot. Which command is most appropriate?

Accepted Answer

journalctl -b. The `journalctl -b` command is the most appropriate because it specifically queries the systemd journal for messages from the current boot. Systemd-journald is the default logging daemon on modern Linux distributions, and `journalctl -b` filters the binary journal to show only entries with a boot ID matching the current boot, which includes kernel messages, service logs, and boot-time events.

Answer

dmesg

Answer

tail -n 50 /var/log/syslog

Answer

cat /var/log/messages

Question 3

A Linux system fails to boot after installing a new kernel. Which step should be taken first to recover the system?

Accepted Answer

Edit GRUB configuration at boot to select the old kernel. When a new kernel fails to boot, the quickest recovery method is to select the previous working kernel from the GRUB boot menu. GRUB typically retains the old kernel entry in its menu (e.g., 'Advanced options for Ubuntu' or a similar submenu), allowing you to boot the system without any external media or reinstallation. This approach avoids the overhead of using a live CD or rescue mode and directly restores functionality.

Answer

Reinstall the original kernel using a live CD

Answer

Boot into single-user mode to fix the kernel

Answer

Use the rescue mode from installation media

Question 4

A system administrator wants to ensure a service named 'app.service' starts automatically on boot in a systemd-based system. Which command should be used?

Accepted Answer

systemctl enable app.service. The correct command is 'systemctl enable app.service' because in systemd-based systems, 'enable' creates the necessary symlinks in the filesystem (typically under /etc/systemd/system/multi-user.target.wants/) to ensure the service starts automatically at boot. In contrast, 'systemctl start' only activates the service immediately without affecting its boot-time behavior.

Answer

systemctl start app.service

Answer

chkconfig app.service on

Answer

update-rc.d app.service enable

Question 5

A system takes a long time to boot due to a service that fails to start. Which systemd command can be used to identify the service causing the delay?

Accepted Answer

systemd-analyze blame. The `systemd-analyze blame` command prints a list of all running units, sorted by the time they took to initialize, making it the direct tool to identify which service is causing a boot delay. Unlike other options, it specifically measures and displays the initialization time of each unit, allowing you to pinpoint the slowest service.

Answer

journalctl -u service

Answer

systemctl status

Answer

systemd-analyze critical-chain

Question 6

Which directory contains the kernel modules for the currently running kernel?

Accepted Answer

/lib/modules/$(uname -r). The kernel modules for the currently running kernel are stored in /lib/modules/$(uname -r). The uname -r command returns the exact kernel release version, and the corresponding directory contains all loadable kernel modules (.ko files) compiled for that specific kernel. This is the standard location used by the kernel and tools like modprobe and insmod to locate and load modules.

Answer

/boot

Answer

/etc/modprobe.d

Answer

/usr/src

Question 7

To add a kernel parameter temporarily to the kernel command line at boot, what key should be pressed in the GRUB menu?

Accepted Answer

e. Pressing 'e' in the GRUB menu enters the edit mode for the selected boot entry, allowing you to temporarily modify kernel parameters on the command line (e.g., adding 'single' for single-user mode or 'nomodeset' for graphics issues). These changes apply only to the current boot and are not saved to the GRUB configuration file.

Answer

b

Answer

r

Answer

c

Question 8

Which TWO of the following are valid methods to list currently loaded kernel modules?

Accepted Answer

lsmod. Lsmod reads /proc/modules and prints the currently loaded kernel modules along with their size and usage count, making it the standard tool for this task. Option D (cat /proc/modules) is also correct because /proc/modules is the kernel-provided virtual file that lists all loaded modules, so displaying it directly shows the same information lsmod parses. Option A (dmesg | grep module) only filters kernel ring-buffer log messages and does not enumerate loaded modules. Option C (modprobe -l) lists available module files on disk rather than loaded modules, and the -l option is deprecated/removed in modern kmod. Option E (modinfo) displays metadata about a specific module file or name, not a list of currently loaded modules.

Answer

dmesg | grep module

Answer

modprobe -l

Answer

modinfo

Question 9

Which TWO commands can be used to set the default boot target (runlevel) in systemd?

Accepted Answer

ln -sf /lib/systemd/system/multi-user.target /etc/systemd/system/default.target. Option E, `systemctl set-default multi-user.target`, is correct because it is the official systemd command that creates or replaces the `/etc/systemd/system/default.target` symlink to point at the desired target, thereby setting the default boot target persistently. Option A, `ln -sf /lib/systemd/system/multi-user.target /etc/systemd/system/default.target`, is also correct because it manually performs the same underlying operation that `set-default` does: replacing the `default.target` symlink so systemd boots into multi-user.target on next boot. Option B, `systemctl isolate multi-user.target`, only switches the running system to that target immediately without changing the persistent default. Option C, `systemctl default multi-user.target`, is not a valid systemd command syntax for setting a default target. Option D, `systemctl enable multi-user.target`, only enables the unit for activation (creating wants symlinks) and does not change the default boot target.

Answer

systemctl isolate multi-user.target

Answer

systemctl default multi-user.target

Answer

systemctl enable multi-user.target

Question 10

Which THREE of the following are valid sources to configure GRUB?

Accepted Answer

/boot/grub/grub.cfg. Option C, /boot/grub/grub.cfg, is correct because it is the primary GRUB 2 configuration file that grub-mkconfig generates and that GRUB reads at boot time to build the menu. Option D, /etc/default/grub, is correct because it holds user-editable variables such as GRUB_TIMEOUT and GRUB_CMDLINE_LINUX that grub-mkconfig sources when regenerating grub.cfg. Option E, /etc/grub.d/, is correct because it contains the executable scripts (e.g., 00_header, 10_linux, 30_os-prober) whose output is assembled by grub-mkconfig into grub.cfg. Option A, /boot/grub/menu.lst, is not a valid GRUB 2 source since menu.lst belongs to the legacy GRUB 1 configuration scheme. Option B, /etc/grub.conf, is likewise a legacy GRUB 1 file (often a symlink to menu.lst on older Red Hat systems) and is not used by GRUB 2.

Answer

/boot/grub/menu.lst

Answer

/etc/grub.conf

Question 11

A system administrator notices that after updating the kernel, the system fails to boot. The administrator wants to boot the previous kernel. Which GRUB menu option should be selected?

Accepted Answer

Advanced options for Ubuntu. The 'Advanced options for Ubuntu' GRUB menu entry provides access to a submenu listing all installed kernel versions, allowing the administrator to select and boot the previous kernel. This is the standard method to revert to a known-good kernel after a failed update, as GRUB dynamically generates entries for each kernel found in /boot.

Answer

Memory test

Answer

Recovery mode

Answer

Boot from first hard disk

Question 12

On a systemd-based system, which file is NOT used for system initialization?

Accepted Answer

/etc/inittab. /etc/inittab is the configuration file used by the traditional SysV init system to define runlevels and control terminal getty processes. On a systemd-based system, systemd does not read /etc/inittab; instead, it uses unit files and targets to manage system initialization, making this file unused for that purpose.

Answer

/etc/fstab

Answer

/etc/systemd/system/default.target

Answer

/lib/systemd/system/sysinit.target

Question 13

Which systemd target corresponds to the traditional runlevel 3?

Accepted Answer

multi-user.target. In systemd, the 'multi-user.target' corresponds to the traditional SysV runlevel 3, which provides a multi-user, non-graphical environment with networking enabled. This target is the default for headless servers and is equivalent to the old /etc/inittab runlevel 3.

Answer

graphical.target

Answer

emergency.target

Answer

rescue.target

Question 14

An administrator wants to add a kernel parameter 'quiet splash' to the default boot entry. Which file should be edited?

Accepted Answer

/etc/default/grub. The correct file to edit is /etc/default/grub because it is the main configuration file for GRUB 2 where kernel boot parameters like 'quiet splash' are defined in the GRUB_CMDLINE_LINUX_DEFAULT variable. After editing this file, the administrator must run update-grub (or grub-mkconfig) to regenerate the actual boot configuration file /boot/grub/grub.cfg.

Answer

/etc/grub.d/00_header

Answer

/etc/grub.conf

Answer

/boot/grub/grub.cfg

Question 15

A system boots in UEFI mode, and the administrator wants to add a new kernel entry to the EFI boot manager. Which tool should be used?

Accepted Answer

efibootmgr. In UEFI mode, the system's boot manager is stored in NVRAM, and `efibootmgr` is the standard Linux tool for creating, deleting, and modifying boot entries in the UEFI Boot Manager. It directly manipulates the UEFI Boot Manager variables (e.g., BootOrder, Boot####) via the efivars kernel interface, allowing the administrator to add a new kernel entry without relying on a bootloader like GRUB.

Answer

grub2-install

Answer

lilo

Answer

mknbi