Introduction
Cloud computing is the delivery of on-demand computing resources—servers, storage, databases, networking, software, analytics and intelligence—over the internet (the “cloud”) to offer faster innovation, flexible resources, and economies of scale. Organizations pay only for the cloud services they use, helping lower operating costs and run infrastructure more efficiently.
Core Cloud Service Models
Infrastructure as a Service (IaaS)
IaaS provides virtualized computing resources over the internet. Users can provision servers, storage, and networking on a pay-as-you-go basis without managing the underlying physical hardware. Examples: Amazon EC2, Google Compute Engine, Microsoft Azure Virtual Machines.
Platform as a Service (PaaS)
PaaS delivers hardware and software tools (usually for application development) over the internet. It removes the overhead of managing infrastructure and enables developers to focus on code. Examples: Heroku, Google App Engine, Azure App Service.
Software as a Service (SaaS)
SaaS delivers software applications over the internet on a subscription basis. Applications are centrally hosted and accessed via a web browser or APIs. Examples: Salesforce, Google Workspace, Microsoft 365.
Cloud Deployment Models
Public Cloud
Services are delivered over the public internet and shared across multiple organizations. Best for scalability and cost-effectiveness.
Private Cloud
Cloud environment dedicated to a single organization, offering more control and security. Can be hosted on-premises or by a third-party provider.
Hybrid Cloud
Combines public and private clouds to allow data and applications to move between them, providing greater flexibility and deployment options.
Community Cloud
Shared cloud infrastructure for a specific community with common concerns (e.g., compliance, security requirements).
Key Benefits
Cloud computing offers several advantages:
- Cost Savings: Reduced capital expenditure and pay-as-you-go pricing.
- Scalability & Elasticity: Rapidly scale resources up or down.
- Agility & Speed: Faster provisioning and deployment.
- Global Reach: Deploy applications close to end users worldwide.
- Managed Services: Offload maintenance, patching, backups to providers.
Common Use Cases
Typical cloud use cases include web hosting, backup and disaster recovery, big data analytics, CI/CD pipelines, development/testing environments, and SaaS application delivery.
Challenges & Considerations
When adopting cloud, consider:
- Security & Compliance: Data protection, encryption, identity and access management.
- Cost Management: Monitoring and optimizing consumption to avoid surprises.
- Vendor Lock-in: Designing apps to be portable across clouds or using multi-cloud strategies.
- Performance & Latency: Ensure appropriate region and network design for low latency.
Core Technologies & Concepts
Key cloud concepts every interviewee should know:
- Virtualization & Containers (VMs, Docker)
- Microservices & Serverless (AWS Lambda, Azure Functions)
- Load balancing, auto-scaling, and CDNs
- Identity & Access Management (IAM), encryption at rest/in transit
Quick Example (AWS CLI)
Example of launching a basic EC2 instance using the AWS CLI:
aws ec2 run-instances --image-id ami-0abcdef12345 --count 1 --instance-type t2.micro --key-name MyKeyPair
How to Answer in an Interview
Start with a concise definition, mention the main service models (IaaS, PaaS, SaaS) and deployment models (public, private, hybrid), highlight 2–3 benefits, and close with a relevant example or use case. Keep the response to 60–90 seconds for general interviews, and dive deeper into technical components if asked.
Summary
Cloud computing transforms how organizations consume IT by providing on-demand access to scalable computing resources. Understanding service models, deployment options, core technologies, and trade-offs (security, cost, vendor lock-in) is essential for any cloud-related role.