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I'd like a program that I can write in an IP address and give it the Subnet mask and have it divide the networks in C level networks.


Something that I can download please, not a website.

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In my day we didn't hire admins who couldn't do it by hand... – Chris S Aug 17 '10 at 18:58
I can do it by hand but why would I waste time with useless crap like that? – Sergio Tapia Aug 17 '10 at 19:11
up vote 6 down vote accepted

ipcalc has a binary program and a site: ipcalc. I don't know if it has binaries for windows but almost every linux distro has it packaged. The command line tool has a lot of options on how to show and how to calculate the subnet.

EDIT: There's how to run it on windows (it's a perl script)

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Also, there are no network classes anymore, so a C class network is an antiquated term. You want to divide it into smaller /24 subnets.

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I thought Class were a term for Subnets depending on the octects that changed... class A has a subnet of, B is and C is These can be further divided into smaller subnets e.g. /24 – Mr Shoubs Aug 18 '10 at 15:56
@Mr Shoubs - Class C was, which is also represented by /24. Not sure what you're getting at. – MDMarra Aug 18 '10 at 18:16

Have you looked at Solarwinds Subnet Calculator?

Google will also point you to lots of online calculators.

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You mean like this

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I wrote one that you give a starting network and mask and then tell it the number of hosts per net and number of nets in your new scheme.

Lets say you start with /12 and tell it you want 10 nets with 254 hosts. Here are the results.

Network           Net Broadcast     CIDR Mask              UsableHosts    13       524,286     AVL  isPrivate    14       262,142     AVL  isPrivate    15       131,070     AVL  isPrivate    16       65,534      AVL  isPrivate    17     32,766      AVL  isPrivate    18     16,382      AVL  isPrivate    19     8,190       AVL  isPrivate    20     4,094       AVL  isPrivate    22     1,022       AVL  isPrivate    23     510         AVL  isPrivate    24     254         REQ 252  isPrivate    24     254         REQ 252  isPrivate    24     254         REQ 252  isPrivate    24     254         REQ 252  isPrivate    24     254         REQ 252  isPrivate    24     254         REQ 252  isPrivate    24     254         REQ 252  isPrivate    24     254         REQ 252  isPrivate    24     254         REQ 252  isPrivate    24     254         REQ 252  isPrivate
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There's also:

This has a lot more options than mentioned by MarkM, but it's also uglier and not as simple.

Which ever one suits your needs.

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