305-300 Container Virtualization Practice Test 4 — 15 Questions

Question 1

Which TWO of the following are valid container orchestration platforms?

Accepted Answer

Kubernetes. Kubernetes and HashiCorp Nomad are widely used orchestration platforms.

Answer

Nginx

Answer

Docker Desktop

Answer

GitLab

Question 2

Which THREE configuration items can be managed by LXC cgroups?

Accepted Answer

CPU shares. Cgroups manage memory, CPU, and device access.

Answer

User permissions

Answer

DNS settings

Question 3

Which TWO commands are used to manage images in Docker?

Accepted Answer

docker tag. 'docker build' creates images, and 'docker tag' renames/labels them.

Answer

docker run

Answer

docker create

Answer

docker attach

Question 4

Which THREE networking modes are natively supported by Docker?

Accepted Answer

bridge. Bridge, host, and none are standard Docker network drivers.

Answer

gateway

Answer

tunnel

Question 5

What is the main advantage of using a container over a virtual machine?

Accepted Answer

Lighter weight and faster startup. Containers share the host kernel, making them significantly lighter and faster to start than VMs.

Answer

Ability to run different kernels

Answer

Stronger security isolation

Answer

No network configuration

Question 6

Which command provides system-wide information about the Docker installation?

Accepted Answer

docker info. 'docker info' shows details like the number of containers, images, and storage driver.

Answer

docker inspect

Answer

docker status

Answer

docker version

Question 7

What is the role of the 'Dockerfile' in the container build process?

Accepted Answer

To provide build instructions. It contains the instructions for building an image.

Answer

To define network topology

Answer

To list running containers

Answer

To store container data

Question 8

In systemd-nspawn, how do you specify a different root directory for the container?

Accepted Answer

-D. The -D or --directory flag specifies the root path.

Answer

--path

Answer

--root

Answer

-r

Question 9

You are running a Docker container and need to map port 8080 on the host to port 80 in the container. Which command argument should you use?

Accepted Answer

-p 8080:80. The -p flag (or --publish) defines port mapping.

Answer

-p 80:8080

Answer

--port 8080:80

Answer

--map 8080:80

Question 10

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?

Accepted Answer

Named volume. Named volumes are specifically designed for persistence and sharing independent of container lifecycles.

Answer

Anonymous volume

Answer

Tmpfs

Answer

Bind mount

Question 11

What does the 'docker rm' command do?

Accepted Answer

Removes a container. 'docker rm' deletes one or more stopped containers.

Answer

Renames a container

Answer

Stops a container

Answer

Removes an image

Question 12

You are migrating a legacy application to an LXC container and need to ensure the container has access to the host's /dev/sda block device. Which configuration key must be added to the container's configuration file?

Accepted Answer

lxc.cgroup.devices.allow = b 8:0 rwm. To allow a container to access host devices, the lxc.cgroup.devices.allow and lxc.mount.entry must be configured properly in the container config.

Answer

lxc.mount.device = /dev/sda

Answer

lxc.cap.sys_admin = 1

Answer

lxc.dev.access = /dev/sda

Question 13

A Docker container running a web server is unable to serve traffic on port 8080. You verify the Dockerfile exposes port 80. What is the correct way to map this for external access?

Accepted Answer

docker run -p 8080:80. The -p flag in docker run is used to map host ports to container ports.

Answer

docker run -p 80:8080

Answer

docker run --net host

Answer

docker run --expose 8080

Answer

docker run -P 8080

Question 14

You are debugging a Docker image buildup that fails at the 'RUN' instruction due to missing network access during the build. What command option should be checked if the build environment uses a proxy?

Accepted Answer

--build-arg. Docker builds do not automatically inherit environment variables from the host's shell unless specified via --build-arg.

Answer

--proxy

Answer

--privileged

Answer

--network=host

Answer

--env-file

Question 15

You are managing an LXC container and need to create a snapshot of the container's root file system. Which command achieves this?

Accepted Answer

lxc-snapshot -n container_name. The lxc-snapshot tool is the standard method for managing LXC container snapshots.

Answer

lxc-checkpoint -n container_name

Answer

lxc-copy -s container_name

Answer

lxc-backup

Answer

lxc-clone --snapshot