Networking is the backbone of any cloud architecture. Day 3 focuses on designing secure, scalable networks using Amazon VPC, and understanding how AWS handles routing, IP addressing, and hybrid connectivity.
🎯 Study Objectives
- Understand Amazon VPC and its components
- Learn about subnets, route tables, NAT gateways, and internet gateways
- Explore security groups vs network ACLs
- Review hybrid connectivity options: VPN and Direct Connect
🧭 VPC Architecture Overview
- VPC (Virtual Private Cloud): Isolated network environment within AWS
- Subnets: Divide VPC into public and private zones
- Route Tables: Control traffic flow between subnets and gateways
- Internet Gateway (IGW): Enables internet access for public subnets
- NAT Gateway: Allows private subnets to access the internet securely
Design with multiple AZs for high availability and fault tolerance.
🔐 Security Layers
| Feature | Scope | Stateful | Notes |
|---|---|---|---|
| Security Groups | Instance-level | ✅ Yes | Allow rules only |
| Network ACLs | Subnet-level | ❌ No | Allow and deny rules |
- Use Security Groups for fine-grained access control
- Apply NACLs for broader subnet-level filtering
🌐 Hybrid Connectivity
✅ VPN
- Encrypted connection over the internet
- Quick to set up, lower cost
- Ideal for dev/test or small-scale hybrid setups
✅ AWS Direct Connect
- Dedicated fiber link to AWS
- High bandwidth, low latency
- Suitable for enterprise-grade workloads
🧠 Exam Tips
- Know how to design public vs private subnets
- Understand routing logic and how NAT/IGW work
- Be able to compare VPN vs Direct Connect
- Expect scenario questions on security group vs NACL behavior
🧪 Hands-On Labs
- Create a custom VPC with public and private subnets
- Configure route tables and attach an internet gateway
- Launch EC2 instances in both subnets and test connectivity
- Set up a simulated VPN connection using AWS VPC Wizard
📎 Resources
✅ Summary
Day 3 reinforces the importance of secure and scalable network design. Whether you’re building a cloud-native app or integrating with on-prem systems, mastering VPC architecture and connectivity is essential for both certification and real-world deployment.