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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