AWS VPC Subnet Planner
VPC subnet planning with exact AWS 5 reserved addresses (.0, .1, .2, .3, .255) and multi-AZ Terraform generation.
Amazon VPC IP Reservation & Multi-AZ Architecture
When configuring an Amazon VPC, AWS reserves exactly 5 IP addresses in every subnet. Unlike standard on-premises subnets that only lose 2 addresses, AWS assigns specific internal functions to the first four addresses (.0 network, .1 VPC router, .2 AmazonProvidedDNS, .3 reserved for future use) plus the last address (.255 broadcast).
Multi-AZ Resilience
Automatically balances subnets across 2 or 3 Availability Zones (e.g., Sydney ap-southeast-2) to ensure high availability and SLA compliance.
3-Tier Separation
Adheres to the AWS Well-Architected Framework: Public ingress subnets, private application subnets, and isolated database subnets.
Production Terraform
Outputs valid, copy-pasteable configuration for the official Terraform AWS VPC module with NAT Gateway and DNS hostnames pre-configured.
Related Cloud Planners
Frequently Asked Questions
How does AWS reserve IP addresses in a VPC subnet?
AWS reserves 5 IP addresses in every subnet: (1) .0 network address; (2) .1 VPC router; (3) .2 AmazonProvidedDNS resolver; (4) .3 reserved for future use; (5) .255 broadcast address. The first usable host in AWS is always offset .4.
What are the minimum and maximum subnet sizes in an Amazon VPC?
In an Amazon VPC, the smallest supported IPv4 subnet size is /28 (16 total IP addresses, providing 11 usable IP addresses after deducting the 5 reserved). The largest supported subnet size is /16 (65,536 total addresses).
Why should VPC subnets be distributed across multiple Availability Zones?
Distributing subnets across multiple AZs ensures that if an entire data center facility or AZ experiences a power outage or hardware failure, traffic automatically fails over to redundant instances in other AZs without service disruption.
Need this designed for a real production environment?
Consult with Gurinder Singh and vetted cloud specialists for Azure Landing Zones, AWS VPC peering, and hybrid connectivity.