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Plan Cloud VPC CIDR Blocks

Size AWS/GCP/Azure VPC and subnet CIDR ranges before you provision.

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/
/0/8/16/24/32
254
Usable hosts
256
Total addresses
Network address192.168.1.0/24
Usable host range192.168.1.1 – 192.168.1.254
Broadcast address192.168.1.255
Subnet mask255.255.255.0
Wildcard mask0.0.0.255
Mask (binary)11111111.11111111.11111111.00000000
IP classC
Address typePrivate (RFC 1918)

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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