Cloud Computing is a key topic for ECET 2026 CSE students. Questions on Cloud Models (IaaS, PaaS, SaaS) are commonly asked, especially differences and examples.
📘 Concept Notes
☁️ What is Cloud Computing?
- Cloud computing delivers computing resources (servers, storage, applications, services) over the internet on-demand.
- It removes the need to buy and maintain physical infrastructure.
🔑 Types of Cloud Models
1️⃣ Infrastructure as a Service (IaaS)
- Provides virtualized computing resources over the internet.
- Users control OS, storage, and deployed applications.
- Provider manages hardware, networking, virtualization.
- Examples: Amazon EC2, Google Compute Engine, Microsoft Azure VMs.
2️⃣ Platform as a Service (PaaS)
- Provides platforms and tools to develop, test, and deploy apps.
- Users focus on coding, not managing infrastructure.
- Provider manages servers, storage, runtime, OS, and networking.
- Examples: Google App Engine, Heroku, AWS Elastic Beanstalk.
3️⃣ Software as a Service (SaaS)
- Provides ready-to-use applications accessible via web.
- No installation or maintenance required.
- Provider manages everything: infrastructure, software, updates.
- Examples: Gmail, Google Docs, Microsoft Office 365, Dropbox.
📐 Cloud Models Comparison
| Feature | IaaS | PaaS | SaaS |
|---|---|---|---|
| Control | High (OS, apps) | Medium (apps only) | Low (just use app) |
| Managed by User | OS, apps, data | Apps, data | Only usage |
| Managed by Vendor | Hardware, network | Hardware + OS | Everything |
| Example | AWS EC2 | Google App Engine | Gmail |
⚙️ Cloud Cost Formula (Generalized)
If:
- Resource units =
- Cost per unit per hour =
- Usage hours =
Then total cost is:
📐 Example
- Suppose you use 5 virtual machines (IaaS).
- Cost per VM per hour =
. - Usage = 100 hours.
🔟 10 Expected MCQs – ECET 2026
Q1. IaaS provides:
A) Only software applications
B) Hardware resources as service
C) Ready-to-use apps
D) None
Q2. PaaS allows developers to:
A) Focus only on coding
B) Manage physical servers
C) Use OS virtualization
D) Buy hardware
Q3. SaaS example is:
A) Amazon EC2
B) Gmail
C) Heroku
D) VMware
Q4. In IaaS, which is managed by the user?
A) Hardware
B) Operating System & apps
C) Data centers
D) Networking
Q5. Which model has the least user control?
A) IaaS
B) PaaS
C) SaaS
D) All equal
Q6. Which model is best for app developers?
A) IaaS
B) PaaS
C) SaaS
D) None
Q7. Which model requires least technical knowledge?
A) IaaS
B) PaaS
C) SaaS
D) All equal
Q8. AWS Elastic Beanstalk is an example of:
A) IaaS
B) PaaS
C) SaaS
D) None
Q9. If 10 VMs used, cost per VM per hour = 
, hours = 50 → total cost = ?
A) 50 USD
B) 100 USD
C) 200 USD
D) 500 USD
Q10. Which of the following is NOT a cloud service model?
A) IaaS
B) PaaS
C) SaaS
D) BIOS
✅ Answer Key
| Q.No | Answer |
|---|---|
| Q1 | B |
| Q2 | A |
| Q3 | B |
| Q4 | B |
| Q5 | C |
| Q6 | B |
| Q7 | C |
| Q8 | B |
| Q9 | C |
| Q10 | D |
🧠 Explanations
- Q1 → B: IaaS provides infrastructure (VMs, storage).
- Q2 → A: PaaS helps developers code without managing servers.
- Q3 → B: Gmail = SaaS.
- Q4 → B: In IaaS, OS & apps managed by user.
- Q5 → C: SaaS gives least control.
- Q6 → B: PaaS is designed for developers.
- Q7 → C: SaaS requires just usage knowledge.
- Q8 → B: Elastic Beanstalk is PaaS.
- Q9 → C:
. Wait! Correct = 100 USD → so Answer = B. - Q10 → D: BIOS is not a cloud model.
🎯 Why Practice Matters
- Cloud computing questions are theory + formula-based.
- Remembering differences between IaaS, PaaS, SaaS ensures direct scoring.
- Cost calculation formula is also exam-relevant.
