Docker Interview Questions and Answer Part – 27

By default, what happens to a Docker Container when the process it is running exits?

• The Container exits. (Ans)
• The Container reboots and restarts the process.
• The Container performs a crash dump.
• The Container continues running in detached mode with a Bash prompt available.

Which of the following commands will install the Docker engine on a CentOS server?

• yum install docker.io
• apt-get install docker.io
• yum install docker (Ans)
• apt-get install docker

In a default installation, how does the Docker daemon natively access features like kernel namespaces and cgroups?

• via capabilities
• via devicemapper
• via LXC
• via libcontainer (Ans)

How are comments added to a Dockerfile?

• Any line starting with a # (Ans)
• Any text following a #
• Any text following //
• Any line starting with //

Which Dockerfile Instruction must be the first Instruction in a Dockerfile?

• MAINTAINER
• RUN
• A comment
• FROM (Ans)

Which transient image layer exists below the rootfs while a container starts?

• The datalink layer
• Layer 1
• Block aggregation layer
• Bootfs (Ans)

Which Dockerfile instruction defines the base image to build from?

• BASEIMAGE
• FROM (Ans)
• BaseImage
• BASE

At the time of recording the course, what is the default storage driver used by CentOS for Docker containers?

• OverlayFS
• NTFS.SYS
• AUFS
• devicemapper (Ans)

Which of the following is the correct way to name a Dockerfile?

• DockerFile
• DOCKERFILE
• Dockerfile (Ans)
• dockerfile

Which of the following is true about RUN Instructions in a Dockerfile?

• All RUN lines are compiled down to a single RUN Instruction
• Each Dockerfile can only contain one
• Each new RUN line creates a new image layer (Ans)
• RUN Instructions only work with containers that have elevated privileges

From a Docker Host, which command can we use to stop a container?

• docker stp
• docker halt
• docker stop (Ans)
• docker-stop

Which of the following is another term to describe container virtualization?

• Storage virtualization
• Hypervisor virtualization
• OS level virtualization (Ans)
• Software Defined Data Center

What is a dangling volume?

• A volume created without a name
• A volume that’s not associated with a container (Ans)
• A volume that’s removed from a running container
• The default volume for the container file system that’s unpacked from the image

What image type is blessed by both Docker and the people behind the software it contains?

• Blessed
• Official (Ans)
• Trusted
• Automated Build

What does docker history do?

• Shows commands that we ran inside a given container
• Shows image history (Ans)
• Shows container history
• Shows a diff of changes in the container layer

Why does Docker for Windows need Hyper-V?

• To run windows containers inside a Windows Server VM and linux containers inside a linux VM
• To run windows containers inside a Windows Server VM
• To run linux containers inside a linux VM
• To run linux containers inside a linux VM and Hyper-V windows containers (Ans)

In the past we had to install software before we could run it. What is the equivalent step with Docker to be able to run software?

• Run a container
• Installs a container
• Create a container (Ans)
• Pulls a container

What docker command executes software?

• docker pull
• docker run (Ans)
• docker ps
• docker stop

When executing the command “docker pull microsoft/aspnet:4.6.2” what does “microsoft/aspnet:4.6.2” refer to?

• Repository
• User
• Registry
• Tag
• Image (Ans)

When using docker-compose, by default, what network are linux containers connected to?

• host
• none
• bridge
• user defined network (Ans)

Rajesh Kumar

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