Docker Interview Questions and Answer Part – 19

What can you use to run multiple containers from a single YAML file?

• Dockerfile
• docker run
• docker-compose (Ans)
• docker run containers.yml

Which of the following is not a benefit of Virtual Memory?

• Use more memory than is physically available
• Processes can use memory as if they are the only process running
• Compress data stored in memory to increase capacity (Ans)
• Don’t have to save entire contents of memory when switching processes

Which of the following is not a benefit of a union filesystem for containers?

• Decrease startup time for containers with images pre-extracted into an image cache
• Save disk space by sharing common files with the host OS filesystem via symbolic links (Ans)
• Share page cache entries to reduce memory overhead
• Save disk space with readonly layers reused among containers

What does it mean for two containers to share a network namespace?

• They share the host’s (or root) network namespace.
• They have isolated virtual network adapters.
• They share a virtual network but still have isolated virtual network adapters.
• They share a single network stack. (Ans)

Which networking approach would you use if you don’t trust an application?

• Share network with other containers
• None (Ans)
• Share with host
• Virtual network

When you create a process with separate namespaces (network, mount, IPC, UTS, PID, and user), what is the net effect?

• It appears as if the process is running on a different machine. (Ans)
• Processses get their own isolated instances of system resources.
• Processes can share system resources.

Why do you use tools like Docker, LXC and rkt?

• To kill processes that consume too much of a system resource
• To configure the additional isolation necessary to create a container (Ans)
• To create VMs to isolate processes
• To emulate virtual resources per process

When a mount namespace is created, what does it contain?

• An empty list of mount points
• The list of mount points passed when creating the new mount namespace
• A default set of mount points from /etc/mountns.defaults
• Essentially a copy of the existing filesystem (Ans)

What does Layered Responsibility mean?

• You can rely upon others for base layers in container images. (Ans)
• You can’t see the layers beneath yours in container images.
• You don’t ever have to see the layers beneath yours in container images.
• You need to validate that all layers are built properly when using an image.

What is a context switch?

• When the executing process is changed (Ans)
• When the executing cgroup is changed
• When the contents of virtual memory is loaded into physical memory
• When the contents of physical memory is swapped to disk

What is a substantial reason for moving from a single node to a multi-node cluster?

• It’s a best practice to use multi-node clusters in production.
• It’s a best practice to run individual containers on individual nodes.
• When containers saturate the resources of a single node (Ans)
• When containers conflict with each other, i.e. port conflicts or file system conflicts

Where is there a natural separation in responsibility when building a cluster?

• Running apps & running VMs
• Node operating system & cluster services
• Machine hardware & operating system
• Provisioning nodes & running apps (Ans)

What is the net effect of a separate network namespace? Each process can have an entirely separate __ .

• hostname
• IP address (Ans)
• filesystem
• list of processes

What runtime or execution environments can be used with a cluster?

• Containers
• chroot Processes
• All of these (Ans)
• Virtual Machines

What does an Image from a site like Docker Hub provide?

• A container’s hostname
• The host filesystem to run a container
• A container’s network configuration
• The entire host filesystem
• A container’s filesystem (Ans)

What is the net effect of a separate IPC namespace? Each process can have an entirely separate ______ .

• message queue (Ans)
• IP address
• filesystem
• list of processes
• hostname

What does a system container run?

• Runs an OS init process, effectively emulating a VM (Ans)
• Runs a single application
• Runs the container runtime
• Runs the host OS init process

Why are images so valuable?

• Manually configuring a hostname for a container is hard work.
• Manually building a filesystem for a container is hard work. (Ans)
• Manually configuring service discovery for a container is hard work.
• Manually configuring networking for a container is hard work.

What do capabilities isolate?

• Privileged operations (Ans)
• Unprivileged processes
• Privileged processes
• Unprivileged operations

Which of the following is NOT an analogy for namespaces?

• A slice of a pizza per process (Ans)
• A whole pizza per process
• Database
• List

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.

I publish technical articles at DevOps School, travel stories at Holiday Landmark, stock market insights at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at TrueReviewNow, and SEO and digital marketing strategies at Wizbrand.