305-300 Practice Exam 3 — 20 Questions

Question 1

You are using an overlay network in Docker Swarm. What is the standard protocol used for the control plane and data plane communication between nodes?

Accepted Answer

VXLAN. VXLAN is the standard encapsulation protocol used by Docker overlay networks.

Answer

BGP

Answer

IPsec

Answer

GRE

Question 2

You need to limit the amount of CPU shares a Docker container can utilize. Which flag should be used?

Accepted Answer

--cpu-shares. The --cpu-shares flag sets the relative CPU weight of a container.

Answer

--cpu-limit

Answer

--cpus

Answer

--max-cpu

Answer

--cpu-weight

Question 3

Which THREE items are typically included in an OpenVZ configuration file?

Accepted Answer

User Beancounters (resource limits). OpenVZ configs contain networking definitions, resource limits (UBC), and OS template references.

Answer

BIOS settings

Answer

Kernel source code

Question 4

You are configuring an OpenVZ container. Which command is used to set the hostname of the container from the host?

Accepted Answer

vzctl set CTID --hostname. 'vzctl set [CTID] --hostname [NAME] --save' is the correct command to update the container's hostname.

Answer

vzcfg

Answer

hostnamectl

Answer

openvz-edit

Question 5

Which TWO items are typically included in a Docker context?

Accepted Answer

Local files in the build directory. The Docker context includes the Dockerfile and the build directory contents.

Answer

The host kernel

Answer

Remote images

Answer

Running containers

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

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

Question 8

What is the default behavior of Vagrant when a box is not found locally on the host machine?

Accepted Answer

It downloads it from the Vagrant Cloud. Vagrant automatically attempts to download the specified box from HashiCorp's Vagrant Cloud (or configured registry).

Answer

It prompts for a path

Answer

It creates an empty machine

Answer

It fails immediately

Question 9

Which signal is sent to a QEMU process when you run 'virsh destroy'?

Accepted Answer

SIGKILL. virsh destroy forces a shutdown, typically by sending SIGKILL to the QEMU process.

Answer

SIGINT

Answer

SIGHUP

Answer

SIGTERM

Question 10

What is the purpose of 'virt-top'?

Accepted Answer

To show real-time statistics for VMs. virt-top is a utility similar to 'top' that shows performance statistics for virtual machines.

Answer

To manage network bridges

Answer

To edit VM configuration files

Answer

To install new guest OSs

Question 11

What is the purpose of the 'rkt' (Rocket) container runtime?

Accepted Answer

To run pods in a secure, pluggable manner. rkt was designed as a pod-native container engine with a focus on security and composability.

Answer

To replace the kernel

Answer

To manage cloud infrastructure

Answer

To provide a GUI for Docker

Question 12

How do you view the logs of a running container?

Accepted Answer

docker logs [container]. 'docker logs' is the command to retrieve logs.

Answer

docker show-logs

Answer

cat /var/lib/docker/logs

Answer

docker log

Question 13

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 14

What is the primary function of the ENTRYPOINT instruction in a Dockerfile?

Accepted Answer

Configuring the executable that runs when the container starts. ENTRYPOINT sets the main command that will execute when the container starts.

Answer

Setting environment variables

Answer

Defining volume mount points

Answer

Specifying metadata

Answer

Installing software packages

Question 15

In a Docker swarm, which mode of service publishing allows incoming traffic to be load-balanced across all healthy container replicas?

Accepted Answer

ingress. The 'ingress' network mode in Swarm allows external traffic to hit any node and be routed to a container via the routing mesh.

Answer

macvlan

Answer

overlay

Answer

host

Question 16

What is the purpose of the 'ENTRYPOINT' instruction in a Dockerfile?

Accepted Answer

To configure the container as an executable. ENTRYPOINT allows you to configure a container that will run as an executable.

Answer

To run build-time commands

Answer

To copy files

Answer

To set environment variables

Question 17

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 18

Which THREE commands are used to manage the lifecycle of an LXC container?

Accepted Answer

lxc-start. lxc-start, lxc-stop, and lxc-destroy are standard commands for managing container states.

Answer

lxc-pause

Answer

lxc-reboot

Question 19

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 20

Which kernel feature provides the isolation necessary for namespaces in container virtualization?

Accepted Answer

Namespaces. Namespaces are a Linux kernel feature that partition kernel resources, such as PID, network, and mount points.

Answer

OverlayFS

Answer

Seccomp

Answer

Cgroups

Answer

AppArmor