6.2.1. Key Concepts Review: Core Networking & VPC

A robust understanding of core networking fundamentals and Amazon VPC design is the foundation for building scalable, secure, and resilient cloud networks.

Scenario: You need to explain the fundamental components of an AWS VPC and how they enable network segmentation and routing for cloud applications.

This review consolidates core networking concepts and Amazon VPC design principles.

Core Networking & VPC Concepts:

• Layered Network Design (OSI Model): Understand Layers 2, 3, 4, 7 for troubleshooting and service application.
• Network Segmentation & Isolation: Limiting "blast radius," controlling traffic flow.
• Routing & Traffic Flow Control: IP addressing (CIDR), route tables, Internet Gateways (IGW), NAT Gateways, Egress-Only IGW, DNS.
• Amazon VPC:
  • Purpose: Logically isolated virtual network.
  • Components: CIDR blocks, Subnets (public/private), Route Tables, Gateways.
  • VPC Endpoints: Private connectivity to AWS services (Interface & Gateway).
  • Route 53 Resolver: Hybrid DNS resolution within VPCs.

⚠️ Common Pitfall: Overlooking the default implicit deny rule in NACLs or the stateless nature of NACLs when troubleshooting.

Key Trade-Offs:

• Control vs. Managed Service: VPC provides granular control over your network, but requires you to manage its components.

Reflection Question: How does understanding core networking concepts (e.g., OSI model layers) and VPC design (e.g., subnets, route tables) provide the foundation for building scalable, secure, and resilient cloud networks?