Docker Interview Questions and Answer Part – 10

What is a dangling volume?

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

Which of the following Windows Features do you need to use Windows Server containers?

• Hyper-V
• Hyper-V and Containers
• Containers (Ans)
• Docker

Which of the following stops all running containers?

• docker rmi $(docker ps -q)
• docker rm -f $(docker ps -q)
• docker rm -f $(docker ps -q) (Ans)
• docker halt $(docker ps -q)

In the past, to find software, we often used standalone web sites hosted by the creator of the software. Now, with Docker, how do we discover software?

• Docker Engine
• Docker Hub (Ans)
• App Stores
• Package Managers
• Still use standalone web sites

What does docker history do?

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

When executing the command “docker pull microsoft/aspnet:4.6.2” what is the “microsoft” piece called?

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

How are image layers coalesced to form a container’s file system?

• A union file system is used to create a union mount point (Ans)
• Files are copied out of layers when creating a container into a union mount point
• Container file systems exist in memory, in a RAM disk, aggregated from image layers

What docker command executes software?

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

Images contain the entire user space, in other words the entire file system for a container. How is this not horribly inefficient in terms of disk space?

• Images use state of the art compression to reduce the disk space requirements
• Image layers are highly optimized to reduce unnecessary components.
• You only pull down the image layers that you need to run your application
• Images are layered and common layers are shared (Ans)

With Docker for Windows, what container types can you run?

• Windows and Linux (Ans)
• Windows and macOS
• Only Windows
• Only Linux

When executing the command “docker pull microsoft/aspnet:4.6.2” what is the “aspnet” piece called?

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

What’s a good analogy for docker stop?

• Removes the container
• Stops the processes running in a container (Ans)
• Stops a single process in a container
• Uninstalls the container

Removing an image is akin to what in traditional software management?

• Uninstalling an application
• Restarting an application
• Stopping an application
• Deleting an installer file or zip file (Ans)

Which of the following commands will start a new container on the same nodes as container C1?

• docker run -d -e affinity==c1 nginx
• docker run -d -e constraint:container==c1 nginx
• docker run -d -e affinity:container==c1 nginx (Ans)
• docker run -d -e constraint==c1 nginx

Which of the following flags tells the Docker daemon to listen on the network using the default secured Docker port?

• -H tcp://0.0.0.0:3375
• -H tcp://0.0.0.0:2376 (Ans)
• -H tcp://0.0.0.0:2375
• -H tcp://0.0.0.0:3376

Which of the following flags turns on TLS authentication for the Docker daemon?

• –tlscert
• –tlsauthenticate
• –tlsenable
• –tlsverify (Ans)

How are custom labels implemented?

• They are stored in an external KV store
• They are applied to the Docker Engine daemon at startup (Ans)
• They are applied to the Docker host as environment variables
• A custom metadata container runs on the Docker host

How does Swarm support a pluggable discovery service backend?

• Using libstorage as an abstraction layer
• Using libkv as an abstraction layer (Ans)
• By publishing an open API that key-value stores can work with

Which of the following is the default scheduling strategy for Swarm clusters?

• Stack
• Spread (Ans)
• Random
• Binpack

Which of the following Swarm components support High Availability?

• Swarm manager and directory service
• Swarm manager and discovery service (Ans)
• Swarm manager and scheduling service
• Just the Swarm manager

Rajesh Kumar

I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.

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