Docker

Docker Interview Questions and Answer Part – 33

January 22, 2020 comments off

Which of the following best decribes a Docker Image?

  • A read-write template for starting one or more containers
  • A point-in-time snapshot of a container used for backups
  • A data volume that can be mounted inside of a container
  • A read-only template for starting one or more containers (Ans)

You have two services running on a Swarm, but they cannot find each other by name. Which of the following could be the reason why?

  • They are on different overlay networks (Ans)
  • They were not manually registered with the Swarm DNS when they were created
  • Service discovery only works on bridge/NAT networks
  • You did not create the Swarm DNS

Which of the following is a loose definition of a Docker container?

  • A VM running a shared kernel with resource limits applied
  • A unikernel running on a hypervisor with resource limits applied
  • An isolated area of an Operating System with resource limits applied (Ans)

What will happen if you start a new container or service and specify a volume that does not currently exist?

  • You will be prompted to create the new volume
  • The command will complete but the container/service will fail to start
  • The command will fail
  • Docker will create the volume for you (Ans)

What are the base requirements to be able to use Docker Secrets?

  • Swarm mode and an external CA
  • Swarm mode and self-encrypting disks for the cluster store
  • Docker in Swarm mode (Ans)
  • Docker

Which of the following are top-level keys in a stack file (Compose v3 file)?

  • Version, deployments, networks, volumes
  • Version and services
  • Version, services, networks, volumes (Ans)
  • Services, pods, networks, volumes

Which of the following is an advantage of Multi-stage Builds?

  • Multi-platform images
  • Better image documentation
  • Faster image builds
  • Smaller images (Ans)

Which of the following is a recommended number of Swarm managers for high availability?

  • 4
  • 3 (Ans)
  • 2

Which of the following best describes a Bridge (NAT on Windows) network in Docker?

  • Token-ring
  • Multi-host overlay network
  • A single-host network (Ans)

How does the HRM know how to route traffic to the correct service?

  • iptables rules
  • It inspects HTTP host headers (Ans)
  • DNS labels
  • Custom load balancer rules

By default, where are Docker daemon logs sent to on a Linux system running systemd?

  • syslog
  • The Linux event viewer
  • journald (Ans)

Which of the following is a major goal of Docker volumes?

  • Data replication
  • Data encryption at-rest
  • Object storage
  • Persistent data (Ans)
  • RAID

Which are the two major kernel building blocks that containers are built from?

  • Capabilities and seccomp
  • Namespaces and kernels
  • Namespaces and control groups (Ans)
  • Capabilities and control groups

Which of the following is a recommended best practice?

  • Keep your images small (Ans)
  • Never use the latest image in a repo
  • Use large images containing lots of tools
  • Only use Docker Hub

Where are Secrets mounted on Linux-based Docker hosts?

  • An encrypted volume mounted at /run/secrets
  • An in memory (tempfs) volume at /run/secrets (Ans)
  • initramfs
  • Solid state volume

How are Docker Secrets created on the command line?

  • docker secret create (Ans)
  • docker swarm secret create
  • They cannot be created on the command line

Which of the following is the best high-level description of a Swarm?

  • A secure cluster of Docker nodes (Ans)
  • A tightly-coupled cluster of Docker container
  • A secure cluster of Docker containers
  • I tightly-coupled cluster of Linux nodes

What is the atomic unit of scheduling in Docker?

  • The service
  • The container (Ans)
  • The pod
  • The stack
  • The swarm

Which of the following commands lets you deploy a Docker Stack called stack1 using a Compose file called myapp.yml?

  • docker service deploy -c myapp.yml stack1
  • docker stack deploy -c myapp.yml stack1 (Ans)
  • docker stack deploy stack1 myapp.yml
  • docker service deploy stack1 myapp.yml
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