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AWS VPC Networking 2026: Complete Guide for DevOps Engineers

SynfraCore·May 2026·11 min read

VPC is the Foundation of Everything on AWS

Every EC2 instance, RDS database, and EKS cluster lives inside a VPC. Get networking wrong and nothing else works correctly.

Standard Architecture

VPC (10.0.0.0/16)
├── Public Subnets  (10.0.1.x, 10.0.2.x) — ALB, NAT Gateway
├── Private Subnets (10.0.11.x, 10.0.12.x) — EC2, EKS nodes
└── Database Subnets (10.0.21.x, 10.0.22.x) — RDS, ElastiCache
Spread across 2-3 Availability Zones for HA

Key Components

•Internet Gateway: Allows public subnet resources to reach internet

•NAT Gateway: Private subnets initiate outbound connections without being publicly reachable. ~$0.05/hour — one per AZ for HA

•Security Groups: Stateful firewall per resource. Default: deny all inbound

•Route Tables: Public subnets → IGW. Private subnets → NAT Gateway

Build with Terraform

hcl

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

Common mistakes: too-small CIDRs, databases in public subnets, single AZ, overlapping CIDRs preventing VPC peering. See AWS VPC Academy.

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