Docker

Docker Interview Questions and Answer Part – 10

January 18, 2020 comments off

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
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