TCS Containers & Kubernetes interview questions

A VM virtualises hardware and boots its own kernel. A container is a process on the host kernel with its view of the world restricted. Everything else, including the security answer, follows from that one difference.

Follow a Deployment change through the API server, controllers, scheduler and kubelet. Each handoff gives you a different place to investigate when a pod never starts.

Three states, three completely different causes, and one command that tells you which you are looking at. The state name says whether the problem is the scheduler, the registry or your own process.

A namespace scopes names, permissions and quotas. It does not scope the kernel or the network by default, and the gap between what people assume it isolates and what it does is where the trouble starts.

The writable layer is part of the container, not the image, and it dies with the container. Everything about volumes follows from knowing which of those two a file is in.

It is Kubernetes with an opinion, and the opinion that catches everyone is that containers do not run as root. A manifest that works on vanilla Kubernetes and fails here usually fails for exactly that reason.

Both run pods, so the answer sounds obvious until an interviewer asks what happens when you delete one. The guarantees are narrower and more specific than most candidates think.

Everyone can recite the three. Explain what each failure causes, and why a badly configured liveness probe is more dangerous than none at all.

PDB governs voluntary disruptions only and does not gate rolling updates at all. Describing it as 'it keeps N pods alive' states the part it does not do, since it constrains voluntary eviction and not the machine that fails.

Three propagation mechanisms live inside this one question and only one of them is automatic. Instant reload is the common assumption and the kubelet has never offered it.

Quotas are admission-time contracts counted in requests, not measured usage. That single sentence explains most quota outages, most quota confusion, and the reason LimitRange must sit beside every quota.

Pull auth resolves on the node before any container exists. Ordering the credential chain and reading 401 against 403 against 429 in the events turns this into a minutes-long diagnosis; without it the only move left is rotating secrets blind.

Tenancy is a dial from policy-based soft isolation to hard cluster boundaries with a virtual-control-plane middle ground. The scored answer picks by blast radius requirements and names what each model still leaves shared.

Best-effort objects, one-hour TTL, deduplicated by count, invisible unless shipped out. Events narrate scheduling and lifecycle decisions; treating them as durable records is the expensive mistake.

Kind precedence orders manifests, hooks jump the queue with their own weights and delete policies, and --atomic plus --wait turn hope into rollback. Split charts along blast radius, not folder aesthetics.

Two-phase deletion, a controller that purges content, finalizers holding the door. Stuck CRD instances, dead webhooks and GitOps recreates are the real story; standards prevent the ticket.

The pair everyone configures and few can explain. QoS hints at eviction risk, but usage versus requests and Pod priority determine node-pressure ranking, and CPU and memory behave completely differently when you exceed them.

A pod is a shared network and storage boundary that happens to contain containers. Once you can say what the containers inside one share, sidecars and init containers stop needing separate explanations.

Service types choose how an application is exposed. Follow the actual traffic path: cloud controllers can target nodes or pods, and internal exposure differs from public exposure.

A Service moves connections and an Ingress reads requests. The gap between those two sentences is hostname routing, path routing and TLS, and it is also why an Ingress object alone does nothing.

The single most common Kubernetes interview question, and the one where a vague answer is most obvious. Every stage you name is a place the interviewer can ask you to debug.

Almost always a finalizer, and the fast fix is the one that loses data. The safe answer explains what the finalizer is protecting against before removing it.