Docker Interview Questions and Answer Part – 22

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

Which of the following open-source tools is the underlying technology for Docker Swarm?

• containerd
• SwarmKit (Ans)
• Kubernetes
• InfraKit
• The Docker daemon

Docker UCP implements RBAC via Grants. Which of the following make up a Grant?

• Subjects, roles, and nodes
• Subjects, roles, and collections (Ans)
• Roles and collections

Which of the following built-in Docker networks creates a single layer-2 container-only network across multiple Docker hosts that can be on different underlying networks?

• Bridge
• MACVLAN
• Overlay (Ans)
• NAT

Which Docker command shows the network ports that a container is exposed on?

• docker container ports
• docker port (Ans)
• docker network –port

What happens when you perform a docker volume rm against a volume attached to a running container?

• The command will fail (Ans)
• The volume will be deleted
• The volume and the container will be deleted
• You will be asked to confirm the command

Which set of container-related Linux tools did Docker’s libcontainer replace?

• LXD
• libc
• AUFS
• LXC (Ans)

Which of the following is needed to deploy a Docker Stack?

• Compose v2 file format
• Kubernetes
• Compose v3 file format (Ans)
• Docker Cloud

What is the name of the configuration file that describes how to build a new Docker image with your app-code inside?

• dockerfile (Ans)
• config.json
• docker-file
• dockerfile.json

Which of the following is the worst number of managers for high availability?

• 1
• 5
• 2 (Ans)
• 7

Which command can you use to get a shell session inside of a container?

• docker container login
• docker container exec (Ans)
• docker container shell
• docker container ssh

Which Docker EE technology performs layer-7 (application layer) load balancing?

• The ingress network
• The Service Mesh
• The HTTP Routing Mesh (HRM) (Ans)

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

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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