Kubernetes & Container Orchestration - Pods, Services & Deployment Architecture Flashcards

Question 1

Pod

Accepted Answer

The smallest deployable computing unit in Kubernetes, representing a single instance of a running process. A Pod encapsulates one or more co-located containers that share network namespaces, IP addresses, and storage volumes.

Question 2

Kubernetes Deployment

Accepted Answer

A higher-level workload API object that declaratively manages a set of identical, stateless Pods via ReplicaSets. It automates rolling updates, rollbacks, self-healing, and declarative scaling.

Question 3

StatefulSet

Accepted Answer

A workload API object used to manage stateful applications. Unlike Deployments, it provides persistent volume claims, unique and stable network identifiers (e.g., `pod-0`, `pod-1`), and ordered, graceful deployment and scaling.

Question 4

DaemonSet

Accepted Answer

A workload object that ensures a copy of a specific Pod runs on all (or selected) worker nodes in a cluster. Commonly used for node-level daemons like log collectors (`Fluentd`) or monitoring agents (`Prometheus Node Exporter`).

Question 5

Kubernetes Service

Accepted Answer

An abstract API object that defines a logical set of Pods and a policy to access them. It provides a persistent IP address, static DNS entry, and load balancing across Pods matched by label selectors.

Question 6

ClusterIP Service

Accepted Answer

The default Kubernetes `Service` type. It exposes the service on an internal, cluster-only IP address. Pods inside the cluster can reach it, but it is entirely inaccessible from external networks.

Question 7

NodePort Service

Accepted Answer

Exposes the service on a static port (by default `30000-32767`) on each Node's public/private IP address. Automatically routes external traffic from `:` to the internal `ClusterIP`.

Question 8

LoadBalancer Service

Accepted Answer

Exposes the service externally using a cloud provider's native load balancer (e.g., AWS ELB, GCP Cloud Load Balancing). It automatically creates underlying `NodePort` and `ClusterIP` routes.

Question 9

Kubernetes Ingress

Accepted Answer

An API object that manages external HTTP and HTTPS traffic routing to internal cluster services. It provides Layer 7 features like SSL/TLS termination, path-based routing, and name-based virtual hosting.

Question 10

ConfigMap vs. Secret

Accepted Answer

`ConfigMap`: Stores non-confidential configuration key-value pairs (e.g., environment variables, config files).
`Secret`: Stores sensitive data (e.g., passwords, TLS certs, API keys) encoded in base64 to prevent plaintext exposure.

Question 11

Liveness Probe

Accepted Answer

A health check configured on a container to determine if it is still running correctly. If the liveness probe fails repeatedly, the `kubelet` kills and restarts the container.

Question 12

Readiness Probe

Accepted Answer

A health check configured to determine if a container is ready to handle incoming network traffic. If the probe fails, the Pod's IP address is temporarily removed from all matching `Service` endpoints.

Question 13

Startup Probe

Accepted Answer

A probe that checks if the application inside a container has initialized. All other liveness and readiness probes are disabled until the startup probe succeeds, preventing premature container restarts for legacy or slow-starting apps.

Question 14

RollingUpdate Strategy

Accepted Answer

The default update strategy for Deployments where old Pods are incrementally replaced with new Pods without downtime. Controlled by parameters `maxSurge` (extra Pods allowed above target) and `maxUnavailable` (max Pods offline during update).

Question 15

Recreate Strategy

Accepted Answer

A Deployment update strategy where all existing Pods are killed simultaneously before new Pods are spawned. Causes application downtime, but guarantees old and new code versions never run concurrently.

Question 16

Headless Service

Accepted Answer

A `Service` defined with `clusterIP: None`. It bypasses load balancing; a DNS lookup on a Headless Service returns an array of direct A/AAAA records for the underlying Pod IPs, essential for stateful clusters like Cassandra or ZooKeeper.

Question 17

Pod Disruption Budget (PDB)

Accepted Answer

An API object that limits the number of Pods of a replicated application that can be down simultaneously during voluntary disruptions (e.g., cluster upgrades, node draining).

Question 18

`kubectl apply -f <file.yaml>`

Accepted Answer

Declaratively creates or updates cluster resources defined in a YAML or JSON file. Maintains a configuration state recorded in the `kubectl.kubernetes.io/last-applied-configuration` annotation.

Question 19

`kubectl exec -it <pod-name> -- /bin/bash`

Accepted Answer

Executes an interactive pseudo-TTY bash session inside a specific container in a running Pod, useful for real-time troubleshooting.

Question 20

`kubectl logs -f -c `

Accepted Answer

Streams (`-f`/`--follow`) stdout and stderr logs in real time from a specific container (`-c`) within a multi-container Pod.

Question 21

`kubectl port-forward pod/<pod-name> 8080:80`

Accepted Answer

Forwards local port `8080` to port `80` on the target Pod, allowing direct local network connection to internal cluster resources without exposing them publicly.

Question 22

`kubectl get pods -A -o wide`

Accepted Answer

Lists all Pods across all namespaces (`-A`), displaying additional details (`-o wide`) such as Pod IP addresses, host node names, and readyness status.

Kubernetes & Container Orchestration - Pods, Services & Deployment Architecture

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