What /24 means
The prefix tells how many bits belong to the network. /24 leaves 8 host bits, so the block has 256 total IPv4 addresses.
Cloud networking lab
CIDRHUB
CIDR calculator for AWS, Azure, GCP, and Kubernetes learners.
Calculate network ranges, usable hosts, wildcard masks, subnet splits, and cloud planning notes from one focused learning workspace.
IPv4Network, broadcast and host ranges
CloudAWS, Azure, GCP and Kubernetes notes
SplitSubnet planner with usable capacity
IPv4 input
Plan a network block
Enter an IPv4 address and prefix to calculate the network address, subnet mask, wildcard mask, broadcast address, usable host range, and provider-specific planning note.
Subnet planner
Split the calculated network
| # | CIDR | Mask | First host | Last host | Broadcast | Usable |
|---|
Learning path
Subnetting concepts that matter in real cloud design.
CIDRHub turns subnet math into practice with beginner-friendly examples for address ranges, usable hosts, growth planning, and overlap risk.
Usable address count
Most IPv4 subnets reserve the first address as the network address and the last address as broadcast, leaving total minus two usable hosts.
Growth planning
Pick blocks large enough for future zones, private endpoints, load balancers, NAT, and clusters without wasting an entire private range.
Overlapping CIDRs
Two connected networks with overlapping CIDRs cannot route cleanly. Check peering, VPN, transit, and on-premises ranges before launch.
Cloud reference
Compare provider rules before you design.
AWS VPCs, Azure VNets, Google Cloud VPCs, and Kubernetes clusters all need clean address planning before peering, VPN, private endpoints, or cluster networking.
VPC planning
A /16 VPC split into /20 or /24 subnets is a common lab pattern. AWS also reserves provider addresses inside each subnet.
- Use private RFC 1918 ranges for most workloads.
- Leave free space for more Availability Zones.
- Document each environment CIDR before peering.
VNet planning
VNets can contain multiple address spaces. Subnets must sit inside the VNet range and cannot overlap with connected networks.
- Reserve gateway and firewall subnets early.
- Account for five reserved subnet addresses.
- Avoid overlap before VNet peering.
Regional subnet planning
Google Cloud subnets are regional. VPCs are global containers, but subnet ranges belong to regions.
- Plan primary and secondary ranges together.
- Keep Kubernetes pod ranges separate.
- Avoid ranges used by auto mode networks.
Cluster range planning
Pod, service, node, ingress, and peered network ranges need clean separation before clusters are deployed.
- Separate pod and service CIDRs.
- Avoid overlap with VPC and on-premises ranges.
- Leave room for node pools and cluster growth.
Blogs
Short reads for cloud networking beginners.
Explore networking, cloud, and CIDR learning articles based on the attached CIDRHub content.
Understanding CIDR in AWS VPC
Learn how CIDR blocks work in AWS Virtual Private Cloud and how to size address spaces before subnet creation.
- Inventory connected networks.
- Pick a repeatable environment pattern.
- Reserve space before creating subnets.
Azure Networking Basics
A practical guide to Azure address spaces, subnets, reserved addresses, and VNet growth planning.
- Plan gateway subnets early.
- Remember Azure reserved IPs.
- Avoid overlap before peering.
Subnetting in Google Cloud
How GCP manages IP ranges in VPC networks, regional subnets, and primary or secondary ranges.
- Choose regional subnets carefully.
- Separate primary and secondary ranges.
- Document auto mode ranges.
K8s Networking Explained
Pods, services, node ranges, and cluster CIDRs explained for cloud learners and junior engineers.
- Keep pod ranges separate.
- Avoid service CIDR overlap.
- Plan ingress and node routing.
About
CIDRHub turns subnet math into practice.
CIDRHub Learning is built for students, cloud certification learners, junior engineers, and anyone planning cloud networks. Created by Mahammad Rafi for CIDRHub, it keeps calculations, examples, and design reminders together so subnetting becomes easier to apply.
Calculate
Network address, broadcast address, masks, host ranges, and subnet splits.
Understand
Plain-language lessons explain the reason behind each number.
Apply
Cloud notes connect CIDR planning to VPCs, VNets, subnets, and clusters.
FAQ
Common CIDR questions.
Quick answers for learners who are starting with IPv4 CIDR, subnetting, and cloud network planning.
CIDR is a compact way to write an IP network. 10.0.0.0/16 means the first 16 bits identify the network and the remaining bits identify addresses inside it.
A /24 has 256 total addresses. In normal IPv4 subnets, the network and broadcast addresses are not assigned to hosts, leaving 254.
The common private IPv4 ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.
Not cleanly. VPN, peering, routing, and Kubernetes service discovery become ambiguous when connected networks overlap.
Need help planning cloud address space?
Use the contact form for subnet planning, cloud learning programs, or CIDRHub feedback.