70-216 - Subnet Tool

Author

Subnet Tool

Bingram

2002-08-28, 3:21 pm

Earlier I posted about a sort of "mnemonic" device for subnetting. Many requests to see the actual table. I have it attached here as text document. Was originally an Excell spreadsheet and looked better, but file formats....

I've found it useful for both exams and real life scenarios (WAN and LAN subnetting for instance).

How to use it? I've seen a couple of ways to rebuild the table from memory. Here's what works for me: Remember masks run from 32 down to 8. Number of class A subnets for an 8 mask is 1. Double that for 9 mask (2), and so on up to 32. The number of subnets in a class A network with a mask of 32 ends up as 16777216. Subtract 2 for 16777214 which happens to be the number of hosts avalible for a network with subnet mask of 8.

Simple math (multiply by two or subtract two)instead of all that 2 to the power of 128 stuff.

No more scientific calculator for me!

frazang

2002-08-29, 11:02 am

...for putting your chart out there. I read your previous post and for some reason couldn't get a picture in my head of what you were explaining. Problem solved. Between this chart and freak's subnetting guide, I think I have this down.

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