Cloud Computing Basics
Target Audience: Beginners, DevOps Engineers, Middleware Administrators, AZ-900 & AZ-104 aspirants.
☁️ What is Cloud Computing?
Cloud Computing is the delivery of computing services such as servers, storage, databases, networking and software over the internet instead of using physical hardware in your own data center.
- No need to buy physical servers
- Resources can be created in minutes
- Scalable and flexible
- Pay only for what you use
☁️ Cloud Service Models
- IaaS (Infrastructure as a Service): Virtual servers, storage and networks.
Use: Full control over OS and applications (Azure Virtual Machines). - PaaS (Platform as a Service): Platform and runtime without managing servers.
Use: Fast application deployment (Azure App Service, Azure SQL). - SaaS (Software as a Service): Fully managed software.
Use: Ready-to-use applications (Microsoft 365).
☁️ Cloud Deployment Models
- Public Cloud: Shared cloud infrastructure.
Use: Cost-effective and scalable. like AWS, Azure, GCP [Pay As you Go] - Private Cloud: Dedicated infrastructure.
Use: High security and compliance. like Azure Stack and AWS Outposts - Hybrid Cloud: On-premise + cloud.
Use: Enterprise flexibility. - Multi-Cloud: Multiple cloud providers.
Use: Avoid vendor lock-in. if one providers gets stuck others can be present
⚡ Cloud Characteristics (NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY- NIST)
- On-Demand Self Service
- Broad Network Access
- Resource Pooling
- Rapid Elasticity
- Measured Service (Pay-as-you-go)
🌍 User Location & Latency
Latency: Delay between request and response.
Use: Deploy applications near users for better performance.
📊 Data Types in Cloud
- Structured Data: SQL databases
- Unstructured Data: Images, videos, logs
- Semi-Structured Data: JSON, XML
🏛️ Compliance & Data Residency
Some industries require data to stay in specific countries due to legal rules.
Use: Banking, Finance, Healthcare, Government.
🔐 Conditional Access
Controls access based on user identity, device and location.
Use: Block access from unknown or insecure devices.
🏗️ Azure Resource Hierarchy
- Management Groups
- Subscriptions
- Resource Groups
- Resources
🌐 Hub-and-Spoke Network Model
Central hub contains firewall and security services, while spokes host applications.
Use: Cost saving and centralized security.
📊 Logs vs Metrics vs Alerts
- Logs: Event records
- Metrics: Performance values (CPU, memory)
- Alerts: Notifications when limits crossed
☁️ Cloud Bursting
Extra workload moves to cloud when on-premise capacity is full.
Use: Payroll processing, exam systems.
🏢 Business Continuity vs Disaster Recovery
- Business Continuity (BCP): Keep business running
- Disaster Recovery (DR): Recover systems after failure
🧑💼 Identity & Access Management (IAM)
Manages users and their access to resources.
Use: Azure Active Directory, RBAC, MFA.
📊 Subscription Limits & Quotas
Limits resources to prevent misuse and control cost.
💰 Cloud Pricing Models
- Pay-as-you-go: Pay only for usage
- Reserved Instances: Discount for long-term usage
- Spot Instances: Low-cost unused capacity
🌐 Cloud Networking
- VNet (Virtual Network): Private network for cloud resources.
Use: Secure communication. - Subnet: Smaller network inside VNet.
Use: Separate web, app and database layers. - NSG (Network Security Group): Firewall rules.
Use: Allow or block traffic. - Load Balancer: Distributes traffic.
Use: High availability. - VPN (Virtual Private Network): Secure tunnel to cloud.
Use: Connect office to cloud. - ExpressRoute: Private dedicated connection.
Use: Faster enterprise connectivity.
🚚 Cloud Migration – 6R Strategy
-
Rehost (Lift and Shift):
Move applications from on-premise to cloud without changing their design.
Use: Fast migration when you want minimal changes and quick cloud adoption. -
Refactor:
Modify application architecture to use cloud-native features like auto-scaling and managed databases.
Use: Improve performance, scalability, and long-term cost efficiency. -
Replatform:
Move applications to cloud with small optimizations but without full redesign.
Use: Gain some cloud benefits while keeping application structure mostly same. -
Retire:
Remove applications that are no longer needed or used.
Use: Reduce cost and simplify IT environment by eliminating unused systems. -
Retain:
Keep certain applications on-premise due to security, compliance, or technical reasons.
Use: When apps cannot be moved to cloud immediately. -
Replace:
Replace existing applications with cloud-based SaaS solutions.
Use: Modernize systems using ready-made cloud software (example: replace on-prem email with Microsoft 365).
📈 Scaling in Cloud
- Vertical Scaling: Increase CPU or RAM
- Horizontal Scaling: Add more servers
- Auto Scaling: Automatic scaling based on load
🔐 Cloud Security Concepts
- HTTPS (HyperText Transfer Protocol Secure)
- RBAC (Role-Based Access Control)
- NSG (Network Security Group)
- JIT (Just-In-Time)
- MFA (Multi-Factor Authentication)
🧠 Cloud Computing Interview Questions
What is Cloud Computing?
Delivering IT services over the internet using pay-as-you-go model.
Difference between Backup and DR?
Backup stores data; DR restores systems.
What is Hybrid Cloud?
Combination of on-premise and cloud.
What is RPO and RTO?
RPO - Recovery Point Objective = How much data loss (time wise) is acceptable if a disaster occurs
RTO -Recovery Time Objective = How quickly the system must be back online after a failure.
💼 Enterprise Real-World Scenarios
- Banking app deployed in multi-region
- Jenkins CI/CD hosted on Azure VM
- Healthcare data stored in India region
- E-learning platform auto scales
- VPN connection from office to cloud
✅ Key Takeaways
- Cloud computing is scalable and cost-effective
- Security and compliance are critical
- Understanding fundamentals helps interviews
- Azure supports enterprise workloads
