Cloud

Cloud Computing Interview Questions with Detailed Answers

1. Cloud Architecture & Design

Q1. How does multi-tenancy work in cloud computing, and how do cloud providers ensure tenant isolation?

Answer: Multi-tenancy allows multiple users (tenants) to share the same cloud infrastructure while ensuring data and resource isolation. Cloud providers use:

Virtualization: Each tenant runs on a separate virtual machine (VM) or container.

Role-based Access Control (RBAC): Restricts access at different levels.

Data Encryption: Ensures data confidentiality.

Namespace Isolation: Ensures network and storage segregation.

Q2. Explain the differences between monolithic, microservices, and serverless architectures in the cloud.

Answer:

Monolithic: All components are tightly coupled into a single codebase. Harder to scale.

Microservices: Breaks applications into smaller services, each handling a specific function. Easier to scale and maintain.

Serverless: No server management; executes code only when triggered. Cost-efficient and auto-scales.

Q3. How does a CDN (Content Delivery Network) enhance cloud application performance?

Answer: CDNs cache content on edge servers close to users, reducing latency and bandwidth costs. They also improve redundancy and load balancing.

Q4. What is the difference between Load Balancing and Auto-Scaling? How do they work together?

Answer:

Load Balancing distributes incoming traffic across multiple servers.

Auto-Scaling adds or removes instances based on demand.

Together, they ensure high availability and fault tolerance.

1. Compute Services

Q5. Compare Virtual Machines (VMs) vs. Containers vs. Serverless Computing in the cloud.

Answer:

Feature

Virtual Machines (VMs)

Containers

Serverless

Boot Time

Minutes

Seconds

Milliseconds

Resource Usage

High

Moderate

Minimal

Scalability

Manual / Auto

Fast

Automatic

Management

Full Control

Less

No Control

Q6. What is "Cold Start" in Serverless Computing, and how can you reduce it?

Answer: Cold start occurs when a function is inactive and needs to start up, causing latency. Solutions:

Provisioned Concurrency: Keeps instances warm.

Lightweight Runtimes: Use Golang, Python, or Node.js instead of Java.

1. Storage & Databases

Q7. Explain the differences between Object Storage, Block Storage, and File Storage.

Answer:

Object Storage (e.g., AWS S3): Best for unstructured data, scalable, good for media files.

Block Storage (e.g., AWS EBS, Azure Disk): Works like hard drives, used for databases and VMs.

File Storage (e.g., AWS EFS, Azure Files): Shared file systems, good for applications requiring file hierarchy.

Q8. How does data replication work in cloud-based distributed databases?

Answer: Data is copied across multiple locations to ensure redundancy. Methods include:

Synchronous Replication: Immediate consistency, but slower.

Asynchronous Replication: Faster but can have data loss in failures.

1. Networking in the Cloud

Q9. How does a Virtual Private Cloud (VPC) work, and what are its key components?

Answer: A VPC is a logically isolated section of a cloud provider's network. Components:

Subnets: Divides network for better control.

Internet Gateway (IGW): Allows internet access.

Route Tables: Defines traffic flow.

Network ACLs & Security Groups: Controls access to resources.

Q10. What are the differences between VPN, Direct Connect, and Peering in cloud networking?

Answer:

VPN: Secure, encrypted tunnel over the internet.

Direct Connect: Dedicated private line, faster and more reliable.

Peering: Connects two cloud networks without routing through the internet.

1. Security & Compliance

Q11. What are the best practices for securing API endpoints in cloud applications?

Answer:

Use OAuth 2.0 & JWT Tokens.

Enable API Gateway Security Features (Rate Limiting, WAF).

Encrypt Requests with TLS.

Q12. Explain the Shared Responsibility Model in cloud security.

Answer:

Cloud Provider: Secures infrastructure.

Customer: Secures data, identity access, and applications.

1. DevOps & Cloud Automation

Q13. What are Infrastructure as Code (IaC) tools, and how do they help in cloud management?

Answer: IaC automates cloud infrastructure deployment using code (e.g., Terraform, CloudFormation, Ansible), making infrastructure scalable and repeatable.

Q14. How do you implement CI/CD pipelines in a cloud environment?

Answer: Use tools like GitHub Actions, AWS CodePipeline, Jenkins, and Kubernetes to automate testing and deployment.

1. Cost Management & Optimization

Q15. How can you reduce cloud costs using Spot Instances, Reserved Instances, and Savings Plans?

Answer:

Spot Instances: Cheaper but can be terminated anytime.

Reserved Instances: Lower cost for long-term commitments.

Savings Plans: Flexible, discounts for consistent usage.

1. Disaster Recovery & Fault Tolerance

Q16. What are RTO (Recovery Time Objective) and RPO (Recovery Point Objective) in disaster recovery?

Answer:

RTO: Time to restore after a failure.

RPO: Maximum acceptable data loss before impact.

1. Cloud Provider-Specific Questions

Q17. How does AWS Lambda differ from Azure Functions and Google Cloud Functions?

Answer:

AWS Lambda: Supports multiple triggers, deep AWS integration.

Azure Functions: Tightly integrated with Microsoft services.

Google Cloud Functions: Best for GCP applications.

Q18. What are the key differences between AWS S3, Azure Blob Storage, and Google Cloud Storage?

Answer:

S3: Best for scalability and ecosystem.

Azure Blob: Good for hybrid use with Azure services.

Google Cloud Storage: High-speed transfers for AI/ML workloads.

1. Hybrid & Multi-Cloud Strategies

Q19. What are the benefits and challenges of a multi-cloud strategy?

Answer:

Benefits: Avoid vendor lock-in, better availability.

Challenges: Increased complexity, integration issues.

Q20. How do cloud service mesh solutions (Istio, Linkerd) help in multi-cloud networking?

Answer:

Provides secure service-to-service communication.

Handles traffic routing across different clouds.