I85PREP
⌘ K
HPOC study materials
HPOC study resources

HPOC practice questions

One question at a time. Build your HPOC understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1OpenVMS System Concepts and Architecture

In OpenVMS, which mode of execution has the highest privilege and is where the operating system kernel itself runs?

  1. Kernel mode Correct answer.
  2. User mode
  3. Supervisor mode
  4. Executive mode

Explanation

OpenVMS defines four processor access modes ranked by privilege: kernel, executive, supervisor, and user. Kernel mode is the most privileged and is where the core operating system executes. Code running in kernel mode can access all memory and privileged instructions.

Question 2OpenVMS System Concepts and Architecture

Which OpenVMS construct is the fundamental unit of code execution that owns a register set and a stack, and can be scheduled independently?

  1. The image
  2. The process
  3. The thread Correct answer.
  4. The job

Explanation

On OpenVMS, a thread is the schedulable unit that owns a register context and kernel stack and executes code. A process is a container that owns resources such as address space and channels and has at least one thread. Images run within processes.

Question 3OpenVMS System Concepts and Architecture

Which OpenVMS component is responsible for managing the page files and the working set of each process?

  1. The scheduler
  2. The class scheduler
  3. The swapper Correct answer.
  4. The job controller

Explanation

The swapper manages memory by trimming working sets and moving processes in and out of the balance set, and it oversees page file usage. The scheduler chooses which thread runs on a CPU. The job controller and class scheduler relate to batch and class-based scheduling rather than memory.

Question 4OpenVMS System Concepts and Architecture

What is the primary purpose of the OpenVMS page file?

  1. To store the permanent copy of executable images
  2. To hold the contents of the system dump on a crash
  3. To hold the process's private read-only code sections
  4. To back up modified virtual memory pages that are not resident in physical memory Correct answer.

Explanation

The page file provides backing storage for virtual pages that have been modified in memory and must be written out when reclaimed. Read-only code pages can be discarded and re-read from the image file, so they do not require page file space. System dumps are written to a separate dump file.

Question 5OpenVMS System Concepts and Architecture

Which OpenVMS data structure records the per-process context such as its PCB, working set list, and page tables?

  1. The process control block (PCB)
  2. The job information block (JIB)
  3. The process header (PHD) Correct answer.
  4. The image header

Explanation

The process header (PHD) is the memory-resident structure holding the working set list, page tables, and other per-process memory management context. The PCB holds process state and scheduling information. The JIB holds job-level accounting and quota information.

Question 6OpenVMS System Concepts and Architecture

In the OpenVMS virtual address space, which region contains the process's own private read/write data and stack?

  1. S1 space
  2. P1 space
  3. S0 space
  4. P0 space Correct answer.

Explanation

P0 space is the per-process region used for private read/write data and the main program stack. P1 space holds the process's control region and user stack for some purposes. S0 and S1 are shared system regions.

Question 7OpenVMS System Concepts and Architecture

Which region of the OpenVMS virtual address space is shared by all processes and contains the resident executive?

  1. S0/S1 system space Correct answer.
  2. P1 space
  3. The user stack region
  4. P0 space

Explanation

System space (S0 and S1) is shared by all processes and contains the resident executive code and data. P0 and P1 are private per-process regions. Sharing the executive in system space means one physical copy serves all processes.

Question 8OpenVMS System Concepts and Architecture

What does the OpenVMS image activator do when a program is run?

  1. It maps the executable image into the process's address space and transfers control to it Correct answer.
  2. It creates a new batch job entry
  3. It compiles the source file into an executable image
  4. It schedules the process onto a processor

Explanation

The image activator locates the image file, maps its sections into the process address space, resolves shareable images, and transfers control to the image's entry point. Compilation is a separate step, and scheduling and batch entry are handled by other components.

Question 9OpenVMS System Concepts and Architecture

A shareable image in OpenVMS is best described as which of the following?

  1. An image that contains only debug symbols
  2. An image that can only be run in batch mode
  3. An image that is mapped once and can be used by many processes at the same time Correct answer.
  4. An image that is loaded into S0 space exclusively

Explanation

A shareable image is a set of routines and data that can be mapped into multiple processes simultaneously, so one physical copy of its read-only code is shared. This reduces memory use and disk I/O compared with linking the code into each image.

Question 10OpenVMS System Concepts and Architecture

Which OpenVMS mechanism allows a process to receive notification of an asynchronous event such as I/O completion?

  1. An AST (asynchronous system trap) Correct answer.
  2. A page fault
  3. A spinlock
  4. A mutex

Explanation

An AST is a routine declared by a process that the system delivers when a specified event, such as I/O completion, occurs. It runs in the context of the process at a defined access mode. Page faults, spinlocks, and mutexes serve different purposes.

Question 11OpenVMS System Concepts and Architecture

At which access mode does a user-declared AST routine normally execute when the requesting process runs in user mode?

  1. Kernel mode
  2. User mode Correct answer.
  3. Supervisor mode
  4. Executive mode

Explanation

An AST runs at the access mode at which it was declared by the requesting process. A user-mode process declaring an AST has it delivered in user mode. This preserves the privilege boundary so user code cannot gain elevated access through AST delivery.

Question 12OpenVMS System Concepts and Architecture

Which OpenVMS synchronization primitive is a lightweight lock that a processor spins on in a multiprocessing system?

  1. An event flag
  2. A semaphore
  3. A spinlock Correct answer.
  4. A mutex

Explanation

A spinlock is a low-level lock used inside the executive on multiprocessor systems; a processor waiting for it busy-waits (spins) rather than blocking. Event flags, mutexes, and semaphores are higher-level synchronization mechanisms that block rather than spin.

Question 13OpenVMS System Concepts and Architecture

In OpenVMS, what is the relationship between a process and an image?

  1. A process and an image are the same object
  2. An image owns the address space and a process is loaded into it
  3. An image may contain many processes that run concurrently
  4. A process may execute one image at a time, and an image runs within a process Correct answer.

Explanation

A process is the execution environment that owns resources such as the address space and channels; an image is the program that runs inside it. A process executes one image at a time (though images can invoke other images). The process, not the image, owns the address space.

Question 14OpenVMS System Concepts and Architecture

Which OpenVMS scheduling entity does the scheduler actually place on a processor?

  1. The job
  2. The process
  3. The image
  4. The thread Correct answer.

Explanation

The scheduler dispatches threads, each of which has its own priority and context. A process may contain multiple threads, and the scheduler chooses among runnable threads. Images and jobs are not directly scheduled onto processors.

Question 15OpenVMS System Concepts and Architecture

Which OpenVMS feature lets a process map a file directly into its virtual address space for direct memory access to file contents?

  1. Mailboxes
  2. Local sections
  3. Logical names
  4. Global sections Correct answer.

Explanation

Global sections allow a file's contents to be mapped into a process's address space, and the same section can be shared among processes. This provides memory-mapped file access. Local sections map anonymous memory private to one process. Mailboxes and logical names are unrelated to file mapping.

Question 16OpenVMS System Concepts and Architecture

What is the primary function of the OpenVMS lock manager?

  1. To manage the page file
  2. To translate logical names to file specifications
  3. To serialize access to shared resources across processes and nodes in a cluster Correct answer.
  4. To schedule batch jobs on queues

Explanation

The lock manager provides distributed, cluster-wide locking so processes on different nodes can coordinate access to shared resources. It supports lock modes such as null, concurrent read, concurrent write, and exclusive. Job scheduling, name translation, and page file management are separate functions.

Question 17OpenVMS System Concepts and Architecture

Which statement best describes the OpenVMS distributed lock manager's role in a cluster?

  1. It is used exclusively for file allocation
  2. It only works within a single node and cannot span nodes
  3. It replaces the need for any local synchronization
  4. It coordinates resource access across nodes so that cluster-wide consistency is maintained Correct answer.

Explanation

The distributed lock manager extends locking across cluster nodes, allowing processes on different systems to coordinate access to shared resources consistently. It does not eliminate the need for local synchronization, and it manages many resource types beyond file allocation.

Question 18OpenVMS System Concepts and Architecture

On OpenVMS, what does a page fault indicate?

  1. The process has exceeded its CPU quota
  2. A privilege violation occurred
  3. A referenced virtual page is not currently resident in physical memory Correct answer.
  4. A hardware failure in a memory module

Explanation

A page fault occurs when a thread references a virtual page that is not resident in physical memory, and the page must be brought in from the page file or an image file. It is a normal part of virtual memory operation, not a hardware failure.

Question 19OpenVMS System Concepts and Architecture

Which OpenVMS structure stores the per-process list of pages currently resident in physical memory?

  1. The working set list Correct answer.
  2. The page table
  3. The process quota list
  4. The channel control block

Explanation

The working set list records the pages currently resident in a process's working set. Page tables translate virtual to physical addresses but do not themselves enumerate the resident set. Quota lists track resource usage, and channel control blocks describe I/O channels.

Question 20OpenVMS System Concepts and Architecture

A program needs to run privileged code that must access all memory and privileged instructions. Which access mode must that code execute in?

  1. User mode
  2. Executive mode
  3. Supervisor mode
  4. Kernel mode Correct answer.

Explanation

Only kernel mode has unrestricted access to all memory and privileged instructions in OpenVMS. Executive and supervisor modes are privileged relative to user mode but are restricted compared with kernel mode. Code requiring full privilege must therefore run in kernel mode.

Question 21OpenVMS System Concepts and Architecture

Which statement about the OpenVMS balance set is correct?

  1. It is the set of threads waiting for the CPU
  2. It is the set of processes whose working sets are currently resident in physical memory Correct answer.
  3. It is the set of files open on the system
  4. It is the set of all images linked into the system

Explanation

The balance set consists of the processes that are currently in memory and eligible to run, meaning their working sets are resident. The swapper adjusts the balance set by swapping processes in and out to manage memory pressure. It is unrelated to linked images, waiting threads, or open files.

Question 22OpenVMS System Concepts and Architecture

What is the purpose of a logical name in OpenVMS?

  1. To provide an alternate name that translates to a file specification or other value Correct answer.
  2. To lock a file against access by other users
  3. To map a global section into memory
  4. To assign a priority to a process

Explanation

A logical name is an entry in a logical name table that translates to a file specification or another value, letting users and programs refer to resources by convenient names. Logical names do not lock files, set priorities, or map sections.

Question 23OpenVMS System Concepts and Architecture

Which OpenVMS component provides the interface through which a user process requests privileged services from the executive?

  1. The lock manager
  2. The system service dispatcher Correct answer.
  3. The image activator
  4. The job controller

Explanation

User processes request privileged services by calling system services, which are dispatched by the system service dispatcher. These calls execute in a more privileged mode on behalf of the caller. The image activator, job controller, and lock manager perform other functions.

Question 24OpenVMS System Concepts and Architecture

An application running in user mode must read a file. Which sequence best describes how the request reaches the executive?

  1. The application directly manipulates the disk controller registers from user mode
  2. The application relies on the scheduler to perform the I/O
  3. The application switches itself permanently into kernel mode
  4. The application issues a system service call, which is dispatched and executes the I/O in a privileged mode on the process's behalf Correct answer.

Explanation

User-mode code cannot perform privileged I/O directly, so it calls a system service. The dispatcher transfers control to the executive, which performs the operation in a privileged mode on behalf of the process and returns the result. The process does not gain permanent kernel mode, and the scheduler does not perform I/O.

Question 25Installation, Configuration, and Booting

During a typical Linux boot sequence, which component is loaded immediately after the firmware hands control to the bootloader?

  1. The kernel image Correct answer.
  2. The init system
  3. The initramfs
  4. The device manager

Explanation

The bootloader loads and executes the kernel image, which then initializes hardware and mounts the initial root filesystem. The initramfs is unpacked by the kernel itself, and the init system only runs after the kernel finishes early setup.

Question 26Installation, Configuration, and Booting

An administrator needs to add a kernel boot parameter persistently on a GRUB2-based system. Which file should be edited to change the default kernel command line?

  1. /etc/fstab
  2. /boot/initramfs.conf
  3. /etc/modprobe.d/options.conf
  4. /etc/default/grub Correct answer.

Explanation

On GRUB2 systems the default kernel command line is defined by GRUB_CMDLINE_LINUX in /etc/default/grub, and the configuration must be regenerated afterward. The other files control mounts, module options, or initramfs contents rather than the kernel command line.

Question 27Installation, Configuration, and Booting

What is the primary purpose of an initial RAM filesystem (initramfs) during boot?

  1. To store the permanent root filesystem
  2. To replace the init system on production servers
  3. To provide drivers and tools needed to mount the real root filesystem Correct answer.
  4. To hold the kernel configuration file

Explanation

The initramfs is a temporary in-memory filesystem containing kernel modules and utilities required to locate and mount the real root filesystem. Once the real root is mounted, control transfers to it and the initramfs is discarded.

Question 28Installation, Configuration, and Booting

A server fails to boot and drops to an emergency shell because the root filesystem cannot be mounted. Which class of problem is the most likely cause?

  1. Disabled SSH service
  2. Incorrect hostname setting
  3. Wrong timezone configuration
  4. Missing or incorrect root= kernel parameter Correct answer.

Explanation

The kernel needs the root= parameter to know which device holds the root filesystem; if it is wrong or the device is unavailable, mounting fails. Hostname, timezone, and SSH settings are applied later and do not affect root mounting.

Question 29Installation, Configuration, and Booting

Which command regenerates the GRUB2 configuration file on a Debian-based system after editing /etc/default/grub?

  1. update-initramfs -u
  2. dracut --force
  3. mkinitcpio -P
  4. grub-mkconfig -o /boot/grub/grub.cfg Correct answer.

Explanation

grub-mkconfig reads the settings and writes the generated grub.cfg, which is the file the bootloader actually reads. The other commands rebuild the initramfs rather than the GRUB menu configuration.

Question 30Installation, Configuration, and Booting

In a UEFI boot process, where does the firmware look for the bootloader by default?

  1. The master boot record of the first disk
  2. The swap partition
  3. The first sector of the root partition
  4. The EFI System Partition Correct answer.

Explanation

UEFI firmware reads boot entries and loads EFI executables from the EFI System Partition, which is formatted FAT. MBR and partition boot sectors are legacy BIOS mechanisms.

Question 31Installation, Configuration, and Booting

Which systemd target corresponds to the traditional multi-user, non-graphical runlevel?

  1. poweroff.target
  2. graphical.target
  3. rescue.target
  4. multi-user.target Correct answer.

Explanation

multi-user.target provides a fully functional multi-user system without a graphical login, matching the old runlevel 3. graphical.target adds a display manager, rescue.target is single-user, and poweroff.target shuts the system down.

Question 32Installation, Configuration, and Booting

An administrator wants a modified kernel parameter to apply only to the next boot without permanently editing configuration files. What is the appropriate action at the GRUB menu?

  1. Press 'c' to enter the GRUB command shell and run update-grub
  2. Press 'e' to edit the selected entry, add the parameter, then boot that entry Correct answer.
  3. Rebuild the initramfs before booting
  4. Boot normally and run sysctl -w

Explanation

Editing the entry at the GRUB menu with 'e' changes the kernel command line for that single boot only and is not persisted. The GRUB shell and initramfs rebuilds do not alter the runtime command line for a one-time test.

Question 33Installation, Configuration, and Booting

A newly installed kernel does not appear in the boot menu. Which step most directly resolves this on a GRUB2 system?

  1. Regenerate grub.cfg with grub-mkconfig Correct answer.
  2. Disable the firewall
  3. Reformat the EFI System Partition
  4. Reinstall the init system

Explanation

The boot menu is built from grub.cfg, so regenerating it picks up newly installed kernels. Reinstalling init, reformatting the ESP, or disabling the firewall does not update the menu entries.

Question 34Installation, Configuration, and Booting

What does the kernel do with the initramfs image after the real root filesystem has been mounted successfully?

  1. It writes it back to /boot for the next boot
  2. It keeps it mounted at /initramfs permanently
  3. It frees the memory used by the initramfs Correct answer.
  4. It merges it into the root filesystem

Explanation

The initramfs is a temporary RAM-based filesystem; once the switch to the real root is complete, the kernel releases its memory. It is not persisted, kept mounted, or merged into the root filesystem.

Question 35Installation, Configuration, and Booting

A system boots directly into an emergency shell reporting that the root account is locked. Which configuration area is most relevant to investigate?

  1. The GRUB timeout value
  2. The /etc/shadow entry for root and the emergency/rescue service settings Correct answer.
  3. The NTP synchronization settings
  4. The network interface configuration

Explanation

Emergency and rescue modes often require a usable root password or a configured sulogin behavior; a locked root account can prevent entry. GRUB timeout, networking, and time sync do not control emergency shell access.

Question 36Installation, Configuration, and Booting

Which file typically defines the default kernel and initrd paths that the bootloader reads on a system using a unified kernel image approach?

  1. /etc/systemd/journald.conf
  2. /etc/kernel/cmdline Correct answer.
  3. /etc/hosts
  4. /etc/grub.d/40_custom

Explanation

On systems using unified kernel images, the kernel command line is often stored in /etc/kernel/cmdline and embedded into the image at build time. The other files control custom GRUB scripts, journal logging, and hostname resolution.

Question 37Installation, Configuration, and Booting

An administrator runs systemctl get-default and sees graphical.target. Which command changes the default boot target to multi-user.target?

  1. systemctl isolate multi-user.target
  2. systemctl enable multi-user.target
  3. systemctl start multi-user.target
  4. systemctl set-default multi-user.target Correct answer.

Explanation

systemctl set-default changes the default.target symlink so the chosen target is used at future boots. isolate switches the current runtime target, enable only creates symlinks for units, and start activates a unit immediately.

Question 38Installation, Configuration, and Booting

A machine using UEFI boots to a firmware shell instead of the operating system after a disk replacement. Which item should be verified first?

  1. The contents of /etc/resolv.conf
  2. The filesystem journal state
  3. The presence of the bootloader executable on the EFI System Partition and its firmware boot entry Correct answer.
  4. The swap partition size

Explanation

UEFI firmware needs a valid EFI executable on the EFI System Partition and a corresponding boot entry (or fallback path) to start the OS. Journal state, DNS configuration, and swap size are irrelevant to firmware handoff.

Question 39Installation, Configuration, and Booting

Which command would you use to rebuild the initramfs on a system that uses dracut?

  1. mkinitcpio -P
  2. dracut --force Correct answer.
  3. grub-install /dev/sda
  4. update-initramfs -u -k all

Explanation

dracut is the initramfs generation tool on many distributions, and --force overwrites an existing image. update-initramfs and mkinitcpio belong to other toolchains, and grub-install installs the bootloader.

Question 40Installation, Configuration, and Booting

A kernel module required to access the root disk is not included in the initramfs. What symptom is most likely during boot?

  1. The network interface gets a duplicate address
  2. The boot process stalls because the root device cannot be found Correct answer.
  3. The display manager starts with the wrong resolution
  4. The system boots normally but with a warning

Explanation

If the storage driver is missing from the initramfs, the kernel cannot see or mount the root device, so boot halts. Resolution and network issues occur later and do not prevent root mounting.

Question 41Installation, Configuration, and Booting

Which GRUB2 directive in /etc/default/grub controls how long the boot menu is displayed before the default entry boots?

  1. GRUB_TIMEOUT Correct answer.
  2. GRUB_DEFAULT
  3. GRUB_DISABLE_RECOVERY
  4. GRUB_CMDLINE_LINUX

Explanation

GRUB_TIMEOUT sets the number of seconds the menu waits. GRUB_DEFAULT selects which entry boots, GRUB_CMDLINE_LINUX sets kernel parameters, and GRUB_DISABLE_RECOVERY governs recovery entries.

Question 42Installation, Configuration, and Booting

After editing a unit file under /etc/systemd/system, what must be done for the change to take effect on the next start of that service?

  1. Run systemctl mask the service
  2. Delete the unit's runtime symlinks
  3. Reboot the machine
  4. Run systemctl daemon-reload Correct answer.

Explanation

systemd caches unit files, so daemon-reload forces it to re-read them before the changed unit is restarted. A reboot would work but is unnecessary, masking disables the unit, and deleting symlinks affects enablement.

Question 43Installation, Configuration, and Booting

A server with an encrypted root volume prompts for a passphrase during boot. Which component is responsible for prompting and unlocking before the real root is mounted?

  1. The login manager
  2. The bootloader itself
  3. The kernel's scheduler
  4. The initramfs Correct answer.

Explanation

Because the root volume must be unlocked before it can be mounted, the initramfs includes the tools and hooks to prompt for the passphrase. The bootloader only loads the kernel and initramfs, while the login manager and scheduler run much later.

Question 44Installation, Configuration, and Booting

On a UEFI system, an administrator wants to add a second boot entry pointing to a rescue loader. Which tool is designed for managing UEFI firmware boot entries from Linux?

  1. modprobe
  2. efibootmgr Correct answer.
  3. fdisk
  4. lsblk

Explanation

efibootmgr reads and modifies the firmware's boot entry list stored in NVRAM. fdisk and lsblk manage or display partitions, and modprobe loads kernel modules.

Question 45Installation, Configuration, and Booting

A system hangs at 'A start job is running for...' during boot and eventually times out. Which approach best identifies the blocking unit?

  1. Reinstall the kernel package
  2. Disable all services and re-enable them one at a time
  3. Increase the GRUB timeout
  4. Inspect the boot log with journalctl -b and check for failed or timed-out units Correct answer.

Explanation

journalctl -b shows the current boot's log, revealing which unit timed out or failed and why. Disabling services indiscriminately is disruptive, and reinstalling the kernel or changing the GRUB timeout does not diagnose the blocking unit.

Question 46Installation, Configuration, and Booting

An administrator adds rd.break to the kernel command line on a system using dracut. What is the effect?

  1. The system boots to a shell inside the initramfs before switching to the real root Correct answer.
  2. The system boots directly to graphical.target
  3. The system skips the initramfs entirely
  4. The system disables all kernel modules

Explanation

rd.break stops the boot inside the initramfs and provides a shell, commonly used to reset a forgotten root password. It does not skip the initramfs, jump to a graphical target, or disable modules.

Question 47Installation, Configuration, and Booting

Which condition would cause GRUB2 to fall back to a manual 'grub>' prompt at boot?

  1. The initramfs is larger than usual
  2. grub.cfg is missing or unreadable at the expected path Correct answer.
  3. The system clock is set to UTC
  4. The kernel command line contains a valid root= parameter

Explanation

If GRUB cannot locate or read its configuration file, it cannot present a menu and drops to the grub> prompt. A valid root parameter, initramfs size, and clock settings do not cause the fallback prompt.

Question 48Installation, Configuration, and Booting

Which sequence correctly describes the handoff order on a modern Linux system?

  1. Firmware, bootloader, kernel, init, services Correct answer.
  2. Kernel, firmware, bootloader, services, init
  3. Init, bootloader, firmware, kernel, services
  4. Bootloader, firmware, init, kernel, services

Explanation

Firmware initializes hardware and hands off to the bootloader, which loads the kernel; the kernel then starts init (PID 1), which brings up services. Any other order contradicts this dependency chain.

Question 49System Management and Startup/Shutdown

In a systemd-based Linux system, which command is used to change the default boot target to a graphical login?

  1. systemctl isolate graphical.target
  2. systemctl start graphical.target
  3. systemctl enable graphical.target
  4. systemctl set-default graphical.target Correct answer.

Explanation

The set-default subcommand updates the default.target symlink so the chosen target is used at the next boot. Isolate and start change the current runtime state only, and enable wires unit dependencies without altering the default target.

Question 50System Management and Startup/Shutdown

Which runlevel in traditional SysV init corresponds to a full multiuser mode with networking but no graphical display manager?

  1. Runlevel 3 Correct answer.
  2. Runlevel 5
  3. Runlevel 6
  4. Runlevel 1

Explanation

In the conventional SysV mapping, runlevel 3 is multiuser with networking and a text console, while runlevel 5 adds a graphical login. Runlevel 1 is single-user and runlevel 6 triggers reboot.