CIDRIP.com shows how a subnet mask affects an IP address, splitting it into a network portion and a host portion.
Move the CIDR slider to any prefix from /0 to /32 and the mask and address update immediately in both binary and decimal, with the network and host bits shown in different colors.
You can Randomize the network portion, the host portion, both, or everything (including the CIDR).
The View buttons can be pressed to set the IP address to the Network ID, Broadcast IP, First Host, Last Host, Next Network, Previous Network, Next IP, and Previous IP. They are also highlighted if the IP displayed happens to be one of these as well.
Keyboard Shortcuts
- ← - Decrease CIDR
- → - Increase CIDR
- ↑ - Randomize Network bits
- ↓ - Randomize Host bits
- R - Randomize Network & Host (same CIDR)
- Space - Randomize Everything, including the CIDR
- N - View Network ID
- B - View Broadcast IP
- F - View First Host IP
- L - View Last Host IP
- Z - Jump to Previous Network
- X - Jump to Next Network
- , - Decrease IP address
- . - Increase IP address
Button Highlighting
A button is dimmed when its action isn't possible at the current mask. For example, a /31 or /32 has no room for a First or Last Host, and a /32 has no Broadcast address.
Note: this webapp does not use RFC 3021 as its purpose is to show you "pure" Subnetting.
Direct Linking
This tool supports linking directly to an IP / CIDR value. Simply add ?ip=5.5.5.5/27 to the URL. Example: https://cidrip.com?ip=5.5.5.5/27.
Note from Ed
I made this tool for two reasons:
- To help visualize the relationship between CIDR, Binary Subnet Masks, and Subnet Masks.
- To help visualize how the CIDR/Subnet Mask affects an IP address
- To cycle through IP addresses and see the landmark IP addresses light up
This was initially a teaching tool for my students, but I thought to give it to the world in hopes that other students (or teachers!) can use it to help in the learning journey.
Feedback? Mention it on my Discord server: pracnet.net/discord.