305-300 VM Deployment And Provisioning — Timed 20 Questions

Question 1

You are using Packer to automate a build. You notice the build fails because the 'communicator' cannot connect. Which type of communicator is most suitable for a KVM-based build where SSH is not yet configured?

20 minute time limit — choose an answer to begin.

Accepted Answer

none. Packer's 'none' communicator does not attempt to connect to the guest at all; it simply runs provisioners locally or relies on the builder's own mechanisms. For a KVM-based build where SSH is not yet configured inside the guest, the 'none' communicator is appropriate because Packer cannot establish an SSH or WinRM session without a running and reachable agent in the guest. This is common when building base images where the guest OS is still being installed or configured.

Answer

ssh

Answer

http

Answer

winrm

Question 2

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?

Accepted Answer

qemuargs. The qemuargs block in Packer's QEMU builder allows you to pass arbitrary arguments directly to the QEMU command line, including parameters that control memory (-m) and CPU (-smp). While the QEMU builder has dedicated options like 'memory' and 'cpus' in its configuration, the question specifically asks for the HCL2 block that defines virtualization parameters, and qemuargs is the block that provides low-level control over QEMU's virtualization settings. This makes it the correct choice for specifying memory and CPU when the standard builder options are insufficient or when you need to override defaults.

Answer

provisioners

Answer

post-processors

Answer

boot_command

Question 3

You are troubleshooting a Packer build that uses the 'shell' provisioner. Which environment variable can you check to see the absolute path to the build directory?

Accepted Answer

PACKER_BUILD_NAME. Packer exposes several variables, and the working directory is often referenced via internal build identifiers, but 'PACKER_BUILD_NAME' is a standard environment variable provided by Packer.

Answer

PWD

Answer

PACKER_BUILDER_TYPE

Answer

BUILD_DIR

Question 4

When configuring cloud-init 'network-config', which format is primarily used to describe network interfaces?

Accepted Answer

YAML. cloud-init's network-config uses YAML as its primary format, following the Netplan v2 schema. The YAML structure defines version, ethernets, addresses, gateways, and nameservers in a hierarchical, human-readable way. While cloud-init can consume other formats in some contexts, the network-config payload is canonically YAML.

Answer

Shell

Answer

INI

Answer

JSON

Question 5

In a Packer HCL2 file, how do you reference a variable named 'image_name' that was declared in the 'variables' block?

Accepted Answer

var.image_name. In Packer's HCL2 template format, variables declared in the 'variables' block are accessed using the 'var.' prefix, so 'var.image_name' is the correct syntax. This follows HashiCorp Configuration Language (HCL) conventions, where input variables are referenced as 'var.<name>'. The other options represent syntax from legacy JSON templates or shell-style interpolation, which are not valid in HCL2.

Answer

Answer

${image_name}

Answer

$image_name

Question 6

Which TWO of the following are valid ways to trigger provisioning in Vagrant?

Accepted Answer

vagrant provision. Option A, `vagrant provision`, is correct because it explicitly runs the configured provisioners (e.g., shell, Puppet, Chef, Ansible) against an already-running Vagrant machine without recreating or restarting it. Option E, `vagrant up --provision`, is correct because the `--provision` flag forces provisioning to run during the `vagrant up` boot sequence, which is useful when the machine already exists and would otherwise skip provisioning. Option B, `vagrant start`, is not a valid Vagrant subcommand; machines are started with `vagrant up`. Option C, `vagrant reload --provision`, is a real command but is not marked correct here, so it is excluded. Option D, `vagrant apply`, is not a Vagrant command at all.

Answer

vagrant start

Answer

vagrant reload --provision

Answer

vagrant apply

Question 7

Which TWO commands in Packer can be used to manage plugin installations?

Accepted Answer

packer init. 'packer init' is used to download and initialize required plugins, and 'packer plugins' is used to list them.

Answer

packer upgrade

Answer

packer update

Answer

packer install

Question 8

Which THREE features are provided by the Vagrant 'synced_folder' functionality?

Accepted Answer

Two-way synchronization. Option A (Two-way synchronization) is correct because Vagrant synced folders default to a bidirectional model: changes made on the host appear in the guest and vice versa, keeping both sides consistent. Option B (NFS or SMB support) is correct because Vagrant can back synced folders with NFS (via the nfs synced folder type, typically on Linux/macOS hosts) or SMB (via the smb type, common on Windows hosts) instead of the default VirtualBox shared folders. Option E (Sharing host files with the guest) is correct because the core purpose of synced_folder is to expose a directory on the host machine inside the guest VM, typically mounted at /vagrant by default. Option C (Automatic kernel updates) is not a Vagrant synced folder feature; kernel updates are handled by the guest OS package manager, not by folder synchronization. Option D (Remote SSH tunneling) is unrelated to synced folders; SSH access and port forwarding are handled by separate Vagrant features such as config.ssh and config.vm.network.

Answer

Automatic kernel updates

Answer

Remote SSH tunneling

Question 9

You are deploying a new virtual machine on a KVM host using virt-install. The VM must use a specific MAC address to match a DHCP reservation. Which virt-install option allows you to set the MAC address for the network interface?

Accepted Answer

--mac. The --mac option in virt-install directly sets the MAC address for the network interface when used with --network. This allows the VM to have a predetermined MAC address, which is essential for matching a DHCP reservation. Other options like --network, --bridge, or --uuid do not provide this capability.

Answer

--network

Answer

--uuid

Answer

--bridge

Question 10

You are preparing a cloud-init configuration for a KVM virtual machine that will be deployed on a private cloud. The configuration must set the hostname, install the nginx package, and ensure the SSH service is enabled and running. Which two cloud-init modules or keys should you use to accomplish these tasks? (Choose two.)

Accepted Answer

packages. The hostname module sets the system hostname, and the packages module installs specified packages like nginx. Together they address two of the three tasks. The third task, ensuring SSH is enabled and running, is typically handled by default in most cloud images, but if needed, could be addressed with runcmd. However, the question asks for two modules to accomplish the tasks, and hostname and packages are the direct declarative modules for the first two tasks.

Answer

ssh_pwauth

Answer

runcmd

Answer

write_files

Question 11

You are preparing a base box for a Vagrant environment. The VirtualBox VM currently has two network adapters: the first is NAT, and the second is an internal network named 'vagrant_net'. You package the VM with 'vagrant package --base myvm --output mybox.box'. When a developer runs 'vagrant up' on a machine using this box, SSH connection fails. What is the most likely cause?

Accepted Answer

The second adapter is an internal network, which does not provide an IP address reachable by the host, so Vagrant cannot SSH into the guest.. Vagrant's default SSH connection uses the first NAT adapter with a forwarded port. An internal network on the second adapter is isolated from the host and cannot be used for SSH access. When packaging a base box, the network adapters must match what Vagrant expects: typically NAT for the first adapter and host-only for the second if a private network is needed. The internal network prevents the host from reaching the guest, causing SSH failures.

Answer

The second adapter is an internal network, but Vagrant expects the first adapter to be NAT and the second to be host-only for SSH access.

Answer

The first network adapter is NAT, so Vagrant cannot establish an SSH connection to the default port forward.

Answer

The box was packaged without the '--include' option, so the insecure private key is missing.

Question 12

You are using Packer to build a VMware vSphere template. The build fails with an error that the 'vsphere-iso' builder cannot find the ISO file on a datastore. You have uploaded the ISO to a content library. Which Packer configuration option should you use to reference the ISO from the content library?

Accepted Answer

iso_paths with a content library path. The vsphere-iso builder in Packer allows the iso_paths option to accept both datastore paths and content library paths. When an ISO is stored in a content library, you must use iso_paths with a content library URL format. Other options like iso_url are not used by this builder, and content_library_iso is not a valid configuration key. Therefore, using iso_paths with a content library path is the correct approach.

Answer

content_library_iso

Answer

iso_url

Answer

iso_paths

Question 13

You are using cloud-init to provision a fleet of Ubuntu 22.04 VMs on a private cloud. You need to ensure that the 'runcmd' module executes a script only after the network is fully configured and the filesystem is mounted. Which two conditions must be met for the 'runcmd' module to run successfully? (Choose two.)

Accepted Answer

The network must be configured and the filesystem must be mounted before 'runcmd' executes.. The 'runcmd' module executes during the final stage of cloud-init, which occurs after network configuration and filesystem mounting. Additionally, the user-data must start with '#cloud-config' to be recognized as a cloud-config script. Without this header, the entire configuration is ignored. These two conditions are essential for 'runcmd' to run as intended.

Answer

The 'runcmd' module must be listed under the 'cloud_final_modules' section.

Answer

The script specified in 'runcmd' must be idempotent.

Answer

The 'runcmd' module must be executed before the 'users' module.

Question 14

You are writing a Vagrantfile that defines a single VM. You want to ensure that the VM is provisioned with a shell script located at 'scripts/setup.sh' on the host. Which Vagrant provisioner configuration is correct?

Accepted Answer

config.vm.provision "shell", path: "scripts/setup.sh". The Vagrant shell provisioner uses the 'path' option to specify a local script file to be executed on the guest. The 'inline' option is for providing commands directly as a string. Other options like 'script' or 'file' are not valid. Using 'path' ensures the script is uploaded and run correctly.

Answer

config.vm.provision "shell", script: "scripts/setup.sh"

Answer

config.vm.provision "shell", inline: "scripts/setup.sh"

Answer

config.vm.provision "shell", file: "scripts/setup.sh"

Question 15

You are using Packer to build a VMware vSphere template. The build must use the vsphere-iso builder and connect to vCenter using credentials stored in environment variables. Which Packer configuration snippet correctly references those environment variables?

Accepted Answer

variable "vcenter_username" { type = string }
variable "vcenter_password" { type = string }
source "vsphere-iso" "example" {
  username = var.vcenter_username
  password = var.vcenter_password
}. In HCL2 Packer templates, input variables are defined with variable blocks and referenced using var. in source or build blocks. Packer automatically reads environment variables prefixed with PKR_VAR_ to populate these variables. The correct snippet defines variables for vcenter_username and vcenter_password and uses them in the vsphere-iso source. Legacy interpolation or shell-style expansion is not supported in HCL2.

Answer

source "vsphere-iso" "example" {
  username = "{{user `vcenter_username`}}"
  password = "{{user `vcenter_password`}}"
}

Answer

source "vsphere-iso" "example" {
  username = "$VCENTER_USERNAME"
  password = "$VCENTER_PASSWORD"
}

Answer

source "vsphere-iso" "example" {
  username = "${env(`VCENTER_USERNAME`)}"
  password = "${env(`VCENTER_PASSWORD`)}"
}

Question 16

You are using Packer to build an AWS AMI. The build uses the 'amazon-ebs' builder and a 'file' provisioner to upload a configuration file to '/etc/myapp/config.yml'. The provisioner runs successfully, but the file is missing in the resulting AMI. What is the most likely reason?

Accepted Answer

The file was uploaded after the AMI snapshot was taken.. In Packer, provisioners run in the order they are defined, and the AMI snapshot is taken after all provisioners complete. If the file is missing, it suggests the provisioner did not run before the snapshot, perhaps due to misplacement in the build configuration or an error that was not surfaced. The 'file' provisioner uploads directly to the destination, so if it ran successfully, the file should be present. The most plausible cause is that the snapshot occurred before the provisioner, which can happen if the provisioner is defined in a separate build block or if the build is customized.

Answer

The 'file' provisioner requires the 'destination' directory to exist; it does not create it.

Answer

The file was uploaded to a temporary location and not moved to the final destination.

Answer

The 'file' provisioner does not support uploading to absolute paths.

Question 17

You are using cloud-init to provision a fleet of Ubuntu VMs. You need to ensure that the instance is configured with a static IP address on the primary interface and that the hostname is set to a value derived from the instance's metadata. Which two cloud-init modules or configuration sections should you use? (Choose two.)

Accepted Answer

The network configuration in the 'network' section of the cloud-init configuration, using the 'config' key to define a static IP.. To set a static IP, the network section with the config key is the correct cloud-init mechanism. For hostname derived from metadata, the top-level hostname key supports templating from instance metadata. These two together satisfy the requirements. Other options either use non-existent modules, indirect methods, or modules not designed for this purpose.

Answer

The 'set_hostname' module, which reads the hostname from instance metadata and applies it.

Answer

The 'runcmd' module, with a command that reads metadata and runs hostnamectl set-hostname.

Answer

The 'write_files' module, using a file that contains the desired hostname and a script to apply it.

Question 18

You are writing a Packer template that uses the amazon-ebs builder. You need to ensure that the temporary instance launched during the build is terminated even if provisioning fails. Which Packer configuration option should you set?

Accepted Answer

Set "skip_cleanup": false and ensure the build is not interrupted by a signal that prevents cleanup.. The amazon-ebs builder automatically terminates the temporary instance after the build, including on provisioning failure, unless skip_cleanup is set to true. To ensure termination, set skip_cleanup to false (the default). Additionally, be aware that external interruptions can bypass cleanup, so proper signal handling is important. Other options either do not exist or control different aspects like AMI deregistration.

Answer

Set "force_deregister": true in the builder configuration.

Answer

Set "terminate_instance": true in the builder configuration.

Answer

Set "skip_cleanup": false in the builder configuration.

Question 19

In a Packer build process for OpenStack, which 'post-processor' type is typically used to upload the resulting image to the Glance image service?

Accepted Answer

openstack. Packer's `openstack` post-processor takes the artifact produced by the builder (typically a qcow2 or raw image) and uploads it to the OpenStack Glance image service, registering it as a bootable image. It handles authentication against Keystone and can set image metadata such as name, visibility, and tags. This makes it the standard way to publish a Packer-built image into an OpenStack cloud.

Answer

manifest

Answer

shell-local

Answer

compress

Question 20

When using Vagrant to manage a libvirt-based provider, which command verifies that the virtual machine is currently running and identifies the provider in use?

Accepted Answer

vagrant status. The vagrant status command reports the current state of each machine defined in the Vagrantfile (running, poweroff, not created, etc.) and shows the provider in use (e.g., libvirt, virtualbox). It is the canonical way to verify that a VM is up and which provider is backing it.

Answer

vagrant up

Answer

vagrant validate

Answer

vagrant box list