305-300 Exam Simulation — 200 Questions

Question 1

Which command is used to remove an unused Docker image?

Accepted Answer

docker rmi. 'docker rmi' is the command to remove an image.

Answer

docker rm

Answer

docker image delete

Answer

docker prune image

Question 2

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 3

You are using BSD Jails and need to start a jail. Which utility is the standard management tool for jail administration?

Accepted Answer

jail. jail is the command to create or start a jail, and jailctl is also sometimes used in managed environments, but jexec is used for executing commands inside.

Answer

jexec

Answer

jails-admin

Answer

jail-manage

Answer

jls

Question 4

Which Dockerfile instruction is used to copy a file from the host file system into the image?

Accepted Answer

COPY. The COPY instruction is the standard way to move files from the build context into the image.

Answer

RUN

Answer

ADD

Answer

PUSH

Answer

IMPORT

Question 5

Which TWO of the following commands can be used to manage virtual networks in libvirt?

Accepted Answer

virsh net-define. virsh net-list and virsh net-define are standard commands.

Answer

virsh net-config

Answer

virsh net-start-all

Answer

virsh net-status

Question 6

Which THREE of the following attributes can be defined within the <memoryBacking> XML block?

Accepted Answer

<hugepages/>. hugepages, locked, and source (type) are all valid components of memory backing.

Answer

<swap-limit/>

Answer

<balloon-rate/>

Question 7

Which command lists all Docker images currently on the host?

Accepted Answer

docker images. 'docker images' or 'docker image ls' lists images.

Answer

docker ps

Answer

docker show

Answer

docker list

Question 8

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 9

You are using systemd-nspawn and want to run a container that shares the host's network namespace. Which flag is required?

Accepted Answer

--network-host. 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.

Answer

--private-network=false

Answer

--network-veth

Answer

--share-net

Question 10

You are configuring an LXC container and need to grant it access to a specific host character device without running the container in privileged mode. Which configuration option in the container's config file should you use?

Accepted Answer

lxc.cgroup2.devices.allow. The lxc.cgroup2.devices.allow directive is the standard way to whitelist specific hardware devices for a container in cgroup2-based environments.

Answer

lxc.cap.keep

Answer

lxc.mount.entry

Answer

lxc.hook.pre-start

Question 11

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 12

You need to create a snapshot of a QCOW2 disk image without stopping the virtual machine. Which qemu-img sub-command should be used?

Accepted Answer

virsh snapshot-create-as --domain vm_name --name snap1 --disk-only. qemu-img snapshot -c creates a snapshot, but it should only be done on offline images. For live snapshots, virsh snapshot-create is required.

Answer

qemu-img create -f qcow2 -b image.qcow2 snapshot.qcow2

Answer

qemu-img snapshot -c snapshot_name image.qcow2

Answer

virsh checkpoint-create vm_name

Question 13

Which command is used to display the XML configuration of a running VM domain named 'webserver'?

Accepted Answer

virsh dumpxml webserver. virsh dumpxml webserver outputs the XML definition of the specified domain.

Answer

virsh export webserver

Answer

virsh show-config webserver

Answer

virsh get-xml webserver

Question 14

What is the primary function of a Docker Registry?

Accepted Answer

To store and distribute images. A registry stores and distributes Docker images.

Answer

To build images

Answer

To run containers

Answer

To manage networking

Question 15

In a FreeBSD Jail, how can you ensure the jail starts automatically at boot?

Accepted Answer

Set jail_enable=YES in /etc/rc.conf. Setting 'jail_enable="YES"' in /etc/rc.conf is required for the jails subsystem to start.

Answer

Create a symlink in /etc/init.d

Answer

Use systemd

Answer

Add a cron job

Question 16

Which Docker command is used to display the resource usage (CPU, memory) of running containers?

Accepted Answer

docker stats. 'docker stats' provides a real-time stream of container resource usage statistics.

Answer

docker top

Answer

docker usage

Answer

docker info

Question 17

Which flag is used to run a container in the background?

Accepted Answer

-d. The -d or --detach flag runs the container in the background.

Answer

-t

Answer

-b

Answer

-i

Question 18

You are using a BSD Jail and want to limit the filesystem access of the jail to a specific directory tree. Which utility or configuration mechanism is primarily used to achieve this?

Accepted Answer

jail.conf path parameter. The 'path' configuration parameter in the jail.conf file defines the root directory of the jail.

Answer

mount -t nullfs

Answer

jail_root_dir

Answer

chroot

Question 19

When using 'docker-compose', which file format is used to define the services?

Accepted Answer

YAML. Docker Compose uses YAML files.

Answer

INI

Answer

XML

Answer

JSON

Question 20

When configuring a Docker volume that needs to be shared between multiple containers, which storage driver storage path is recommended to ensure persistent data availability if the host reboots?

Accepted Answer

-v /host/path:/container/path. Using a named volume or a bind mount to a host directory ensures persistence beyond the container lifecycle.

Answer

--link

Answer

--tmpfs

Answer

--volume-driver=none

Answer

--memory