194 questions total · 3pages · All types, answers revealed
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Which instruction in a Dockerfile is best suited for installing packages to minimize image size?
This cleans the apt cache, reducing the layer size.
Why this answer
Combining the update and install commands with 'rm -rf /var/lib/apt/lists/*' in a single RUN command prevents layer bloat.
Which command is used to start a VM that has been defined?
Starts the domain.
Why this answer
virsh start vm_name boots the virtual machine.
How do you define a new libvirt virtual network from an XML file named 'net.xml'?
net-define is the correct command.
Why this answer
virsh net-define net.xml loads the network configuration into libvirt.
In a Packer build process for OpenStack, which 'post-processor' type is typically used to upload the resulting image to the Glance image service?
This handles the image upload to Glance.
Why this answer
The 'openstack' post-processor is designed to handle the registration of the image into the OpenStack Glance service.
Which THREE of the following XML elements are used to define a virtual disk in a domain?
Defines driver properties.
Why this answer
<source>, <target>, and <driver> are the primary sub-elements of a <disk> entry.
Which TWO commands are valid for inspecting container network settings?
Displays detailed container info including networking.
Why this answer
'docker inspect' provides detailed JSON, and 'docker network inspect' shows network-specific details.
What is the purpose of the 'rkt' (Rocket) container runtime?
rkt focused on security, standards, and pod-native execution.
Why this answer
rkt was designed as a pod-native container engine with a focus on security and composability.
You are performing a live migration of a VM using libvirt. The source and destination hosts share a common storage pool (NFS). Which option should be used with 'virsh migrate' to ensure only the memory state is transferred?
This flag specifies that storage is already available on the destination.
Why this answer
--live --copy-storage-none allows migration without moving the disk image if the storage is shared.
Which THREE of the following steps are involved in performing a manual disk migration of a VM?
Updating paths for the new disk location.
Why this answer
Copying the image, editing the XML, and redefining the domain are the correct workflow steps.
Which command shows the history of layers in a Docker image?
This is the correct command.
Why this answer
'docker image history' displays the layers and the commands that created them.
Which command is used to display the XML configuration of a running VM domain named 'webserver'?
dumpxml extracts the current XML state.
Why this answer
virsh dumpxml webserver outputs the XML definition of the specified domain.
You are using Docker and want to create a volume that is shared between multiple containers and persists even if the containers are deleted. What is the best approach?
Managed by Docker and designed for persistence.
Why this answer
Named volumes are specifically designed for persistence and sharing independent of container lifecycles.
A cloud-init configuration file is failing to apply the 'write_files' module. Which log file on the target instance should you examine to diagnose the parsing error?
This log tracks the internal processing of the cloud-init modules.
Why this answer
Cloud-init logs all activities to /var/log/cloud-init.log, while /var/log/cloud-init-output.log captures stdout and stderr from the modules.
What is the role of the 'Dockerfile' in the container build process?
Dockerfile defines the image creation steps.
Why this answer
It contains the instructions for building an image.
A VM is hanging because of a specific hardware emulation bug in QEMU. You need to enable the 'qxl' video device to see if it resolves display issues. What is the XML tag to define the video device in the domain config?
Correct XML for defining a QXL video device.
Why this answer
The <video> tag with a <model type='qxl'/> sub-tag defines the video device.
Which TWO of the following are benefits of using the QCOW2 image format?
Efficient disk usage.
Why this answer
Snapshots and dynamic allocation are key benefits of QCOW2.
Which TWO of the following are valid storage drivers used by Docker to manage image layers?
Overlay2 is the default and recommended driver.
Why this answer
Overlay2 and aufs are both well-known storage drivers for Docker.
Which TWO of the following commands are used for VM disk image management?
Creates new images.
Why this answer
qemu-img info and qemu-img create are standard image management commands.
What is the primary function of the cloud-init 'runcmd' module?
This is the primary purpose of runcmd.
Why this answer
The 'runcmd' module is used to execute arbitrary shell commands during the boot process of an instance.
You are troubleshooting a Docker container that cannot reach the internet despite the host having connectivity. The container uses the default bridge network. Which iptables chain is most likely causing the block?
Docker injects rules into the FORWARD chain to control inter-network traffic.
Why this answer
Docker adds rules to the FORWARD chain in the filter table to manage traffic between the bridge network and external networks.
Which command provides system-wide information about the Docker installation?
Shows system configuration.
Why this answer
'docker info' shows details like the number of containers, images, and storage driver.
Which THREE of the following are common cloud-init modules?
Manages software installation.
Why this answer
'users-groups', 'runcmd', and 'packages' are all standard, well-documented modules in the cloud-init ecosystem.
Which THREE directives are valid under the cloud-init 'users' configuration section?
The account username.
Why this answer
'name', 'ssh_authorized_keys', and 'groups' are all standard configuration keys for the user module.
You need to run a container that requires access to the host's network namespace directly to perform packet capture. Which Docker run flag should you use?
This flag joins the container to the host network stack.
Why this answer
The --network host flag allows a container to share the host's networking namespace, providing full access to host network interfaces.
You have an active domain named 'myvm'. How do you gracefully shut it down?
Correct command for graceful shutdown.
Why this answer
virsh shutdown myvm sends an ACPI signal to the guest for a graceful shutdown.
Which flag is used to run a container in the background?
Detached (background) mode.
Why this answer
The -d or --detach flag runs the container in the background.
What does 'QEMU' stand for?
Official meaning.
Why this answer
Quick Emulator.
When migrating a domain with virsh, which TWO of the following options can be used to ensure the migration is successful if the destination host has a different CPU architecture or feature set?
This ensures the VM runs with CPU features compatible with the host.
Why this answer
The '--cpu-mode' and '--migrate-disks' related flags help handle compatibility during migration.
What is the purpose of the 'ENTRYPOINT' instruction in a Dockerfile?
This sets the default command for the container.
Why this answer
ENTRYPOINT allows you to configure a container that will run as an executable.
Which TWO of the following are key features of the QEMU-KVM hypervisor?
KVM's primary role.
Why this answer
Hardware-assisted virtualization and device emulation are the core roles of KVM and QEMU.
How can you force a refresh of a libvirt storage pool named 'isos'?
Correct command for refreshing a pool.
Why this answer
virsh pool-refresh isos triggers a re-scan of the storage pool.
You are configuring an OpenVZ container. Which command is used to set the hostname of the container from the host?
The vzctl command is the primary tool for OpenVZ management.
Why this answer
'vzctl set [CTID] --hostname [NAME] --save' is the correct command to update the container's hostname.
Which TWO methods can be used to pass configuration data to cloud-init during instance creation?
The primary configuration file.
Why this answer
Cloud-init accepts configuration via 'user-data' (the primary config) and 'metadata' (key-value pairs, though less common for full configs).
In a Docker environment, you are observing that container logs are consuming too much disk space. Which logging driver should you configure to limit the number and size of log files?
This driver allows log rotation using max-size and max-file.
Why this answer
The 'json-file' logging driver supports 'max-size' and 'max-file' options to rotate and cap logs.
Which TWO of the following are true regarding container orchestration platforms?
Orchestration is primarily for scaling and deployment management.
Why this answer
Orchestration platforms manage scaling and automated recovery of containers.
Which TWO of the following are valid libvirt storage pool lifecycle commands?
Starts a pool.
Why this answer
virsh pool-start and virsh pool-destroy are standard lifecycle commands.
You are managing a Xen host and need to live-migrate a domain between two physical servers. The migration fails with a domain lock error. Which command is the standard way to initiate a live migration while ensuring the target host is prepared to receive the domain?
This is the correct syntax for initiating a live migration in Xen.
Why this answer
The 'xl migrate' command is the standard interface for Xen live migration, requiring the target host to be accessible and the source domain to be running.
In a Packer HCL2 file, how do you reference a variable named 'image_name' that was declared in the 'variables' block?
This is the correct syntax for referencing input variables.
Why this answer
In HCL2, variables are accessed using the 'var.' prefix followed by the variable name.
Which command is used to stop all running containers?
This stops all containers currently identified by ps -q.
Why this answer
'docker stop $(docker ps -q)' pipes the IDs of running containers to the stop command.
When managing storage pools using virsh, which command would you use to list all defined storage pools, including those that are inactive?
The --all flag includes inactive pools.
Why this answer
virsh pool-list --all displays all pools regardless of their current status.
You are using Packer to build a custom image for KVM. Which HCL2 block is specifically required to define the virtualization parameters like memory and CPU for the builder?
The qemuargs block allows direct manipulation of the QEMU command line arguments used for the builder instance.
Why this answer
The 'qemu' builder in Packer utilizes specific configuration blocks to define virtual hardware settings when interfacing with KVM/QEMU.
Which Packer builder is most appropriate for creating an image specifically for Amazon Web Services (AWS)?
This is for AWS AMIs.
Why this answer
The 'amazon-ebs' builder is the standard choice for creating Amazon Machine Images (AMIs).
You are using libvirt to manage a QEMU VM. You want to pass a specific host USB device with vendor ID 1234 and product ID 5678 to the guest. Which XML element is used inside the <devices> block to define this?
Correct XML structure for USB passthrough.
Why this answer
The <hostdev> element with mode='subsystem' and type='usb' is used for USB passthrough.
You are using systemd-nspawn and want to run a container that shares the host's network namespace. Which flag is required?
This flag instructs systemd-nspawn to use the host's network namespace.
Why this answer
The --private-network flag disables the network, while omitting it or specifically using --network-veth allows various configurations; however, to share the host's namespace, one must use --network-host.
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