Plan Cloud VPC CIDR Blocks
Size AWS/GCP/Azure VPC and subnet CIDR ranges before you provision.
IPv4 subnetting reference. /31 and /32 are handled per RFC 3021 (point-to-point and single-host). All math runs locally in your browser.
Cloud VPC tips
AWS VPCs accept /16 to /28. Plan your VPC CIDR and per-subnet CIDRs here before running Terraform — resizing later is painful.
Cloud providers reserve ~5 addresses per subnet (not just 2), so subtract a little more from the usable count for AWS/Azure.
Leave room between subnet ranges for future expansion; don't pack /24s back-to-back if you might need to grow one.
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