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Infosys · Docker & Kubernetes
Practice Docker & Kubernetes questions specifically asked in Infosys interviews – ideal for online test preparation, technical rounds and final HR discussions.
Questions
21
Tagged for this company + subject
Company
Infosys
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Subject
Docker & Kubernetes
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Go through each question and its explanation. Use this page for targeted revision just before your Infosys Docker & Kubernetes round.
If you set limits lower than your expected demand or omit requests, pods may be scheduled without guaranteed resources and compete badly for CPU or memory, causing throttling or eviction. Properly balancing requests and limits is essential for predictable performance.
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`docker image prune` removes all dangling images (untagged images) and frees up disk space. Efficient image cleanup is important for CI/CD systems and build hosts to avoid storage bloat.
docker image prune -a
Docker is a containerisation platform that lets you bundle an application plus its dependencies into a lightweight, portable unit. This ensures consistent behaviour across different environments. It is widely used to solve the "works on my machine" problem by packaging code and dependencies together. :contentReference[oaicite:0]{index=0}
Typically you create a container from an image, you run it, then stop it when done, and finally you remove it. Understanding lifecycle states helps in container management. :contentReference[oaicite:5]{index=5}
The `docker ps -a` command shows all containers (running and stopped). This is a fundamental command for container management and diagnosing container states. :contentReference[oaicite:3]{index=3}
docker ps -a
Tags (such as ‘1.0’, ‘latest’, ‘release’) help you keep track of different versions of your image, facilitate roll-backs, and clarify what is running or being deployed in an environment.
Using `-v host_path:container_path` is a standard way to mount a host directory (bind mount) into a container path. This ensures data persists beyond the container lifecycle when needed.
docker run -v /data:/app/data myapp
A `--tmpfs` mount in Docker creates a memory-backed filesystem inside the container. It is useful when you need fast access, or want to keep data truly ephemeral (for example caches, scratch files) that you don’t want persisted to disk.
docker run --tmpfs /app/cache myapp
Docker Compose allows you to define services, networks and volumes for a multi-container application in a compose YAML file, then bring them up with a single command. It simplifies orchestration for local development and small deployments.
The Scheduler is part of the control-plane and assigns pods to nodes based on resource availability and constraints. Other components like the API server, etcd and controller-manager also sit in the control-plane.
In Swarm mode, services are the basic deployment unit. `docker service create --name web --image nginx --replicas 3` instructs the swarm to run three tasks of nginx, distribute them across available nodes, and manage their state.
The Pod lifecycle phases include Pending (waiting scheduling or image pull), Running (containers started successfully), Succeeded/Failed (terminated) and Unknown. Knowing these phases helps in debugging.
The fields `maxSurge` and `maxUnavailable` in a Deployment control how many new pods are created above the desired count and how many old pods can be unavailable during the update. This governs the pace and safety of rolling updates.
If only limits are defined, the scheduler does not have a clear baseline of requested resources, which may lead to inefficient placement or contention. Requests define what is guaranteed and used for scheduling, while limits cap consumption.
You can pause a rollout using `kubectl rollout pause deployment/<name>` to stop applying changes mid-update, inspect behavior and then resume with `kubectl rollout resume`. This is useful when you want to verify a new version before full deployment.
Kubernetes may evict pods when a node is under resource pressure, such as low memory, or when pods exceed their resource limits. Eviction frees node resources and protects system stability, so setting requests and limits is vital.
A Docker image is a read-only template that includes application code, libraries and runtime dependencies. A container is a live, running instance created from that image, with its own writable layer. Understanding this helps you differentiate build time (image) vs runtime (container).
Custom networks give you stronger isolation, logical grouping of containers, predictable DNS names for containers, and better control of communication. These are useful when you build multi-container applications and want services to talk in a controlled way.
Docker Hub is a registry service for storing Docker images. You can push your custom images and pull them on other hosts. It supports both public and private repositories. :contentReference[oaicite:8]{index=8}
A Deployment manages stateless applications by controlling ReplicaSets underneath, enabling rolling updates, rollbacks and maintaining desired replicas.
A PersistentVolume (PV) is a piece of storage in the cluster provisioned by an administrator or dynamically created, and it can be claimed by pods via PersistentVolumeClaims (PVCs). This separation provides flexibility in storage management and decouples storage from pods’ lifecycles.