Docker Interview Questions and Answer Part – 9

Where does the file system come from for a container?

• From a remote network share hosted through Hyper-V
• From the machine the container is started on
• From the image used to create the container (Ans)
• From another special container called a parent container

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

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

How can you get files out of a container onto the host? Assume a process in a container is writing files, like ffmpeg saving the contents of a converted video. Where do you write this data?

• Write files to the default host file system mounts at C:\host or /mnt/host on Linux
• Write files to a volume mounted from the host (Ans)
• Write files to network shares
• Write files to the container file system, all writes are automatically copied to the host file system in the same folder

How can you see the output of a process running in a detached container?

• docker run -it
• docker logs (Ans)
• docker ls
• docker exec -it
• docker output

Why do containers exist?

• To make it easier to use virtual machines
• A replacement for monolithic operating systems
• A replacement for virtual machines
• To make it easier to use software (Ans)

Which of the following allows you to add files from the host to a running container?

• docker cp (Ans)
• docker share
• docker commit
• docker volumes
• docker add

Which of the following is a good analogy for creating a container?

• Running software
• Installing software (Ans)
• Extracting a zip file
• Downloading software

What is a repository on Docker Hub?

• A single image
• A collection of images (Ans)
• An image ta
• A user account

On a computer, with either Linux or Windows installed, there’s a program that runs in a privileged mode that abstracts hardware and provides services to other processes. What is this program?

• Application
• User space
• User
• Kernel space
• Kernel (Ans)

What does docker-compose help us avoid? Excessive calls to __?

• docker pull
• docker stop
• docker build
• docker rm
• docker run (Ans)

How can I run another process inside a running container?

• docker start
• docker ps
• docker exec (Ans)
• docker run

What does an image contain?

• The user space files (Ans)
• The operating system
• Only an application’s files
• Both the user and kernel space files
• The kernel space files

On Windows 10 which container types can you run?

• Hyper-V Containers (Ans)
• Both Hyper-V and Windows Server Containers
• Windows 10 Containers
• Windows Server Containers

What is a dangling image?

• An intermediate part of the chain of image layers
• An image that’s not associated with a volume
• An image that’s not associated with a tag (Ans)
• An image that’s not associated with a running container

In the past, to launch an installed application, we would run an executable file. How does Docker run software?

• Install a container
• Runs an executable (Ans)
• Pull a container
• Create a container

How can processes in different containers talk to each other when using docker-compose?

• Pass IP addresses in configuration files
• Embedded DNS for Service Discovery (Ans)
• Linking containers
• Pass IP addresses in environment variables

What’s a good analogy for docker exec?

• It’s similar to installing software
• Allows you to run additional processes in a container (Ans)
• Allows you to run additional processes outside a container
• Allows you to run additional processes in new containers

To get Ctrl+C to work to kill a container, what should you pass when running the container?

• -it (Ans)
• –name
• -d
• -p

Say you have the following output from docker ps:
57cf9c689955 docs/docker.github.io “/bin/sh -c ‘jekyll s” About an hour ago Exited (137) About an hour ago grave_tesla
Which of the following does not work as a container identifier (CID) when running a command like the following?
docker stop
docker start
docker rm

• 57
• gra (Ans)
• grave_tesla
• 57cf9c689955

What’s the primary purpose of docker-compose?

• Pull and push images
• Build containers
• Build containers, volumes, and networks (Ans)
• Build images
• Cleanup containers.

Rajesh Kumar

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