CIDR Range
-
Total Hosts
-
Netmask
-
Wildcard Mask
-
Network Address: -
Broadcast Address: -
First Usable IP: -
Last Usable IP: -
Understanding IP Subnetting & CIDR
Subnetting is the practice of dividing a network into two or more smaller networks. It helps conserve IP addresses and improves security/performance. CIDR (Classless Inter-Domain Routing) is the modern notation used to represent these blocks (e.g., `/24`).
Common CIDR Cheat Sheet
| CIDR | Subnet Mask | Total IPs | Use Case |
|---|---|---|---|
| /32 | 255.255.255.255 | 1 | Single Host (Firewall Whitelist) |
| /30 | 255.255.255.252 | 4 (2 Usable) | Point-to-Point Links |
| /24 | 255.255.255.0 | 256 (254 Usable) | Standard LAN / Office Network |
| /16 | 255.255.0.0 | 65,536 | Large AWS VPC |
| /8 | 255.0.0.0 | 16,777,216 | Entire Class A Network (e.g., 10.0.0.0) |
Key Terms Explained
- Network Address: The first IP in the block. Identifies the subnet itself. Cannot be assigned to a device.
- Broadcast Address: The last IP in the block. Used to communicate with all devices in that subnet.
- Usable Hosts: Total IPs minus 2 (Network + Broadcast). This is how many servers/computers you can actually have.