AKS interview questions and answers

1 – If you delete cluster then all data get deleted?

No, the Persistent Volume is not deleted because it is stored separately from the Pod. This is one of the main purposes of using a Persistent Volume — to retain data even if the Pod is deleted or recreated.

2 .Difference Between kubectl apply vs kubectl create

Command	Description	Use Case
kubectl create	Creates a new resource	Use only when the resource does not exist
kubectl apply	Creates or updates a resource	Use when you may modify configs and want to re-apply

✅ kubectl create – One-time creation

kubectl create -f deployment.yaml

• Creates the resource from deployment.yaml
• ❌ Will fail if the resource already exists: pgsqlCopyEditError from server (AlreadyExists): deployments.apps "my-app" already exists

kubectl apply – Declarative & idempotent

bashCopyEditkubectl apply -f deployment.yaml

• If the resource doesn’t exist, it creates it
• If it exists, it updates it based on the changes in the YAML
• Supports declarative configuration (preferred in GitOps, CI/CD)

Best Practice

Use kubectl apply for all YAML-based deployments in production and CI/CD pipelines — it’s declarative, idempotent, and update-friendly.

why we dont use replication controller in aks

We don’t use ReplicationController in AKS (Azure Kubernetes Service) or modern Kubernetes clusters because it is deprecated and replaced by more advanced controllers like Deployments and ReplicaSets.

Here’s a breakdown of why ReplicationController is not used in AKS or modern Kubernetes environments:

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🔄 1. ReplicationController is Obsolete

• ReplicationController (RC) is the original controller to manage the number of pod replicas.
• It is now replaced by ReplicaSet, which offers more features and better support in current Kubernetes versions.

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🚀 2. Deployment is the Standard Way

• In AKS (and all modern Kubernetes setups), we use Deployments which manage:
  • Rolling updates
  • Rollbacks
  • Declarative pod updates
• Deployments automatically use ReplicaSet internally to manage pod replicas.

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⚙️ 3. Advanced Features Missing in RC

ReplicationController does not support:

• Rollback of versions
• Canary or blue/green deployments
• Strategies for zero-downtime upgrades
• Label selectors as flexible as ReplicaSet

✅ Summary: Use Deployment Instead

Feature	ReplicationController	ReplicaSet	Deployment
Manages pod replicas	✅	✅	✅
Rolling updates	❌	❌	✅
Rollbacks	❌	❌	✅
Recommended in AKS	❌	⚠️ (used by Deployment)	✅

What is an Annotation?

Annotations are key-value pairs, like labels.

Unlike labels, they are not used for selection (e.g., no selector.matchAnnotations).

Instead, they are used to store extra metadata that might be:

• Used by tools
• Referenced by controllers or policies
• Just informational

🆚 Labels vs Annotations

Feature	Labels	Annotations
Used for selecting/filtering	✅ Yes	❌ No
Max size	Small (~63 chars per key/value)	Larger (up to ~256KB)
Purpose	Identify objects	Store metadata/config for tools
Used by controllers/tools	✅ Sometimes	✅ Frequently

🛠️ How to Add an Annotation

Example in YAML:

yamlCopyEditapiVersion: v1
kind: Pod
metadata:
  name: my-pod
  annotations:
    example.com/maintainer: "team@example.com"
spec:
  containers:
    - name: nginx
      image: nginx