Free Practice Questions for LPI 305-300 Exam

Containerd is an industry-standard container runtime that uses Runc (a low-level container runtime) by default, but can be configured to use others as well1. Containerd manages the complete container lifecycle of its host system, from image transfer and storage to containerexecution and supervision1. It supports the standards established by the Open Container Initiative (OCI)1. Containerd does not require the Docker engine and Docker CLI to be installed, as it can be used independently or with other container platforms2. Containerd is not a text file format, nor does it run in each Docker container or provide DHCP client functionality. Containerd is not the initial process run at the start of any Docker container, as that is the role of the container runtime, such as Runc3. References: 1 (search for “containerd”), 2 (search for “Containerd is an open source”), 3 (search for “It uses rune to start containers”).

 cloud-init uses the /var/lib/cloud/ directory to store status information and configuration information retrieved from external sources, such as the cloud platform’smetadata service or user data files. The directory contains subdirectories for different types of data, such as instance, data, handlers, scripts, and sem. The instance subdirectory contains information specific to the current instance, such as the instance ID, the user data, and the cloud-init configuration. The data subdirectory contains information about the data sources that cloud-init detected and used. The handlers subdirectory contains information about the handlers that cloud-init executed. The scripts subdirectory contains scripts that cloud-init runs at different stages of the boot process, such as per-instance, per-boot, per-once, and vendor. The sem subdirectory contains semaphore files that cloud-init uses to track the execution status of different modules and stages. References:

Configuring and managing cloud-init for RHEL 8 - Red Hat Customer Portal

vsphere - what is the linux file location where the cloud-init user …

The WORKDIR instruction sets the working directory for any subsequent RUN, CMD, ENTRYPOINT, COPY and ADD instructions that follow it in the Dockerfile1. The RUN instruction executes commands in a new layer on top of the current image and commits the results2. The RUN cd command does not change the working directory for the next RUN instruction, because each RUN command runs in a new shell and a new environment3. Therefore, the file test is created in the root directory (/) of the container image, not in the /tmp directory. References:

Dockerfile reference: WORKDIR

Dockerfile reference: RUN

difference between RUN cd and WORKDIR in Dockerfile

 The Linux kernel module that must be loaded in order to use QEMU with hardware virtualization extensions is KVM (Kernel-based Virtual Machine). KVM is a full virtualization solution that allows a user space program (such as QEMU) to utilize the hardware virtualization features of various processors (such as Intel VT or AMD-V). KVM consists of a loadable kernel module, kvm.ko, that provides the core virtualization infrastructure and a processor specific module, kvm-intel.ko or kvm-amd.ko. KVM must be loaded into the kernel of the host system in order to use the virtualization extensions of the host system’s CPU. This enables QEMU to run multiple virtual machines with unmodified Linux or Windows images, each with private virtualized hardware. KVM is integrated with QEMU, so there is no need to load it into the kernel of each virtual machine or the first virtual machine. KVM also does not require paravirtualization, which is a technique that modifies the guest operating system to communicate directly with the hypervisor, bypassing the emulation layer. References:

Features/KVM - QEMU

Kernel-based Virtual Machine

KVM virtualization on Red Hat Enterprise Linux 8 (2023)

To attach a container to a network when creating it, the --network flag must be used with the name of the network as the argument. The --network flag specifies the network mode for the container. By default, the network mode is bridge, which means the container is connected to the default bridge network. However, if a custom network is created, such as isolated_nw in this case, the container must be explicitly attached to it using the --network flag. For example, to create a container named web1 and attach it to the isolated_nw network, the command would be:

docker create --name web1 --network isolated_nw nginx

The other options are not valid parameters for docker create. The --eth0, --ethernet, and --attach flags do not exist. The --alias flag is used to specify an additional network alias for the container on a user-defined network, but it does not attach the container to the network. References:

docker network create | Docker Documentation1

docker create | Docker Documentation

Networking overview | Docker Docs2

Xen supports two types of guest systems: paravirtualized guests (PV) and fully virtualized guests (HVM).

Paravirtualized guests (PV) are guests that have been modified to run on the Xen hypervisor. They use a special kernel that communicates with the hypervisor through hypercalls, and use paravirtualized drivers for I/O devices. PV guests can run faster and more efficiently than HVM guests, but they require the guest operating system to be ported to Xen and to support the Xen ABI12.

Fully virtualized guests (HVM) are guests that run unmodified operating systems on the Xen hypervisor. They use hardware virtualization extensions, such as Intel VT-x or AMD-V, to create a virtual platform for the guest. HVM guests can run any operating system that supports the hardware architecture, but they incur more overhead and performance penalties than PV guests. HVM guests can also use paravirtualized drivers for I/O devices to improve their performance12.

The other options are not correct. Xen does not support foreign architecture guests (FA), emulated guests, or container virtualized guests.

Foreign architecture guests (FA) are guests that run on a different hardware architecture than the host. For example, running an ARM guest on an x86 host. Xen does not support this type of virtualization, as it would require emulation or binary translation, which are very complex and slow techniques3.

Emulated guests are guests that run on a software emulator that mimics the hardware of the host or another platform. For example, running a Windows guest on a QEMU emulator. Xen does not support this type of virtualization, as it relies on the emulator to provide the virtual platform, not the hypervisor. Xen can use QEMU to emulate some devices for HVM guests, but not the entire platform14.

Container virtualized guests are guests that run on a shared kernel with the host and other guests, using namespaces and cgroups to isolate them. For example, running a Linux guest on a Docker container. Xen does not support this type of virtualization, as it requires the guest operating system to be compatible with the host kernel, and does not provide the same level of isolation and security as hypervisor-based virtualization56.

References:

Xen Project Software Overview - Xen

Xen ARM with Virtualization Extensions - Xen

Xen Project Beginners Guide - Xen

QEMU - Xen

Docker overview | Docker Documentation

What is a Container? | App Containerization | VMware

The output of xl list shows the state of the domains. The domain with ID 6, Ubuntu, has a state of “b—”. This means that the domain is blocked, which means it is idle or waiting for I/O.

https://xenbits.xen.org/docs/unstable/man/xl.1.html

The virt-diff command-line tool can be used to list the differences between files in two virtual machines or disk images. The output shows the changes to a virtual machine’s disk images after it has been running. The command can also be used to show the difference between overlays1. To specify two guests, you have to use the -a or -d option for the first guest, and the -A or -D option for the second guest. For example: virt-diff -a old.img -A new.img1. Therefore, the correct command to list all differences between the disk images vm1-snap.img and vm1.img is: virt-diff -a vm1-snap.img -A vm1.img. The other commands are not related to finding differences between disk images. virt-delta is a tool to create delta disks from two disk images2. virt-cp-in is a tool to copy files and directories into a virtual machine disk image3. virt-cmp is a tool to compare two files or directories in a virtual machine disk image4. virt-history is a tool to show the history of a virtual machine disk image5. References:

21.13. virt-diff: Listing the Differences between Virtual Machine Files …

21.14. virt-delta: Creating Delta Disks from Two Disk Images …

21.6. virt-cp-in: Copying Files and Directories into a Virtual Machine Disk Image …

21.7. virt-cmp: Comparing Two Files or Directories in a Virtual Machine Disk Image …

21.8. virt-history: Showing the History of a Virtual Machine Disk Image …

 Packer is a tool that automates the creation of identical machine images for multiple platforms from a single source configuration. Packer works by creating an instance based on a source image, which is a pre-existing image that serves as a starting point. Packer then connects to the instance through a network connection, such as SSH or WinRM, and runs various commands and scripts to install and configure software within the instance. Packer then shuts down the instance and creates a new system image from it, which can be used to launch new instances. Packer supports many platforms, such as AWS, Azure, VMware, Docker, and others. Packer does not install any software or run any daemon within the target image, nor does it periodically connect to the running instances to re-apply the template. Packer also does not modify the source image directly, but creates a new image from the modified instance. References:

Packer by HashiCorp

HashiCorp Packer - Build Automated Machine Images

Introduction | Packer | HashiCorp Developer