Docker Interview Questions and Answer Part – 33

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

Rajesh Kumar

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