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Docker & Kubernetes · Question Set
Docker Networking & Volumes interview questions for placements and exams.
Questions
11
Included in this set
Subject
Docker & Kubernetes
Explore more sets
Difficulty
Mixed
Level of this set
Go through each question and its explanation. Use this set as a focused practice pack for Docker & Kubernetes.
The overlay driver allows containers on multiple hosts (for example in Swarm or other orchestrators) to connect via a virtual network spanning hosts. Understanding this is key when operating across hosts or data-centres.
For complete preparation, combine this set with full subject-wise practice for Docker & Kubernetes. You can also explore other subjects and sets from the links below.
Volumes are Docker-managed directories stored in Docker’s space and abstracted from the host path. Bind mounts tie a specific path on the host into a container. That difference impacts portability, backup and security.
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
Docker volumes live outside the container’s writable layer. When you remove a container, its writable layer is lost, but data in volumes remains. That means you can update or replace containers without losing persistent data (for example databases, logs, configuration). Use volumes when you need stateful services or want to keep data outside ephemeral containers.
One way is to mount the volume into a temporary container, use `docker run --rm -v volume_name:/backup ubuntu tar czf /backup/data.tar /mountpoint` to archive the data, copy the archive to the other host (scp/s3), then on the destination create a volume and restore with `tar xzf data.tar -C /mountpoint`. You could also use `docker cp` or storage driver snapshotting. Having a repeatable strategy for data migration helps avoid loss of data in production.
The command `docker network connect <network_name> <container>` attaches a running container to the specified network without stopping it. This supports dynamic networking adjustments in multi-container systems.
docker network connect mynet container1
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
Mounting host directories or using default networks can expose your host file system or allow unintended container-to-host or container-to-container communication. Mitigation practices include: limiting container privileges, restricting mount points to specific directories, using user namespaces, avoiding bind mounts of sensitive host paths, defining explicit networks rather than default, implementing network policies (in orchestrators) or firewalls between containers, and scanning container images for vulnerabilities. Understanding both storage and network attack surfaces is important for production readiness.
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.
In a docker-compose.yml file, you can define networks and within a service use the key `networks: { yournet: { aliases: ["myalias"] } }`. This alias then lets other containers refer to the service by that name. It improves readability and decouples service names from container names.
By default, Docker uses the bridge network driver for containers on a single host. This network allows containers to communicate with one another and with the host unless configured otherwise.