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Network Subnets for Humans

© January 2009 Anthony Lawrence

Your computer doesn't care if it's on a Class C subnet or a Class A. Your computer doesn't care if you are using, or as your subnet. If you've set up everything else to match, it's all going to work.

However, human beings are easily confused, especially when it comes to multiple subnets. For example, let's say you have a remote office and you need to set up a VPN between that and your main office. Your main office currently uses (a class C network). What should the branch office use?

If you have no idea what I'm talking about, see Networking 101 here.

You could use As noted, your computers won't care - as long as it's a different subnet, the specific choice doesn't matter. However, I'd suggest doing something more helpful for humans.

For example, I'd either use or or for the remote office because the addresses will be more obviously different to humans like me. The is markedly different, but the and also stand out because the "100" is two digits longer than the "1".

If it makes sense to do so, I'd also select a different range for servers and DHCP cients. If the main office uses through for machines, I might use through at the remote - again, this is only to make it more obvious to humans looking at network reports and tools.

I would also avoid mixing Class B and Class C networks if at all possible. Unless you must use Class B, I'd stay clear of that entirely because sooner or later something will get configured as and cause confusion.

Remember - none of this matters at a technical level. It can just help avoid human mistakes and confusion.

Got something to add? Send me email.

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Tue Jan 27 22:21:13 2009: 5253   BrettLegree

Wow - you just described how I set up my IP's (different ranges for workstations/laptops, servers, DHCP clients) - I must have taken a page from the book of Tony or something.

Logical and human readable. I wonder how many other folks do it this way.

(Hopefully someone in our IT department at work - then again, hope is sometimes for fools.)

Tue Jan 27 22:32:13 2009: 5254   TonyLawrence

Great minds run in the same sewers.. uhh, channels..

Tue Jan 27 22:34:57 2009: 5255   BrettLegree

I guess this would be one time when it's okay to have our minds in the gutter ;)

Thu Jan 29 11:58:59 2009: 5262   NickBarron

Fits in with what I do, it just makes logical sense to me, good link in the article back to some previous ones regarding subnets etc.

Happy commuter reading, thanks Tony


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