Want this checked while you draw?
NetworkSketch runs the same checks on your network diagram as you build it, together with reused switch ports and unlinked devices, and exports a PDF with a device inventory and cabling schedule.
Paste your addresses and subnets to find duplicate IPs, addresses outside every subnet, network and broadcast addresses in use, overlapping subnets and gateways in the wrong place. It runs in your browser: nothing you paste is uploaded or stored.
NetworkSketch runs the same checks on your network diagram as you build it, together with reused switch ports and unlinked devices, and exports a PDF with a device inventory and cabling schedule.
Any address that appears more than once, with the names of everything using it.
If you list subnets, each address is matched to the most specific subnet that contains it. Anything that fits none of them is flagged; it's usually a typo or a device left on an old network.
Assigning the first or last address of a subnet (for example 10.10.20.0 or 10.10.20.255 in a /24) breaks connectivity for that device. /31 and /32 subnets are allowed to use every address.
Two subnets that share addresses, a gateway outside its own subnet, and a gateway set to the network or broadcast address.
Yes. The checker is a script that runs on this page in your browser. Nothing you paste is sent to a server, saved, or logged, and the page has no analytics or tracking.