🌐 Cloud Networking: VPC, Subnets & Routing Made Simple

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Hello Tech Enthusiasts,

In our last edition, we broke down Load Balancers—how they help manage traffic, improve uptime, and scale applications. 📌 If you missed it, check it out here: [Load Balancers: Keeping Traffic Smooth & Scalable]

This week, we dig into one of the most essential — yet often overlooked — components of any cloud setup: networking.

🧱 What is a VPC?

A Virtual Private Cloud (VPC) is like a data center within the cloud — but one that you fully control.

• You define the IP range
• You create subnets
• You control inbound/outbound traffic
• You attach resources like VMs, databases, load balancers

It’s your isolated private network inside the cloud provider’s infrastructure (like AWS, Azure, or GCP).

Think of it as your company’s own office building inside a shared cloud city.

Understanding Subnets

A Subnet (short for Subnetwork) is a logical segmentation within a VPC. It divides your network into smaller chunks.

You can have:

• Public Subnets – where internet-facing components like load balancers live
• Private Subnets – for internal servers, databases, or back-end services
• Isolated Subnets – for ultra-sensitive components with no internet access

Each subnet is tied to a specific availability zone and helps you design for redundancy and security.

Routing Tables

A Routing Table defines how traffic flows in and out of your subnets.

• Want all outbound traffic from a subnet to go through a NAT Gateway? Route it.
• Want private subnets to talk to each other but not the internet? Configure accordingly.

You can route traffic to the internet, other subnets, VPN gateways, peering connections, or even on-premise environments.

Network Security: NACLs vs Security Groups

Both are crucial for DevSecOps and cloud compliance.

Real-World Use Case

You’re building a 3-tier web app on AWS:

• Public Subnet: Application Load Balancer
• Private Subnet: App servers in an Auto Scaling Group
• Isolated Subnet: RDS database (no internet access)
• Routing Table: Ensures app servers can pull updates via NAT Gateway
• Security Group: Only ALB can talk to app servers, and only app servers can talk to the DB

This structure balances security, availability, and scalability — the holy trinity of cloud-native architecture.

DevOps Relevance

💡 Misconfigured networking causes more CI/CD pipeline failures than bad code.

• Broken VPC peering? Pipeline timeouts.
• No route to internet? Artifact downloads fail.
• Wrong security group? Health checks fail.
• No NAT? Your app can’t talk to GitHub, Docker, or S3.

Solid networking = smooth DevOps delivery.

Bonus Tip: Use Terraform for VPC-as-Code

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
  enable_dns_support = true
  enable_dns_hostnames = true
  tags = { Name = "main-vpc" }
}        

Use modules to reuse VPC + subnet patterns across environments.

🔍 What’s Next?

Next week, we’ll dive into DNS & IP Management in the Cloud.

📌 Stay tuned for: “DNS & IP Management in the Cloud” 🚀

📢 Follow for More: [Wamiq Siddiqui]

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