305-300 Practice Test 6 — 10 Questions

Question 1

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 2

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 3

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 4

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 5

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 6

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 7

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 8

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 9

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 10

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