Create a Subnetting Cheat Sheet

(Rene Molenaar) #1

This topic is to discuss the following lesson:

(Srinivasan C) #2

Hi Rene,

Cheat Sheet Table under Step 4 and Step 5 needs some correction. Please revisit and correct , it will be very useful for all of us.

Thanks ,



(Rene Molenaar) #3

Hi SV,

Thanks, I just fixed a few errors. If you encounter any, please let me know and I’ll correct them.


(Kelly N) #4

Another easy way to get the wildcard value is to subtract the value in each octet in the subnet mask from 255.

Example: subnet mask

1st Octet: 255 - 255 = 0

2nd Octet 255 - 255 =0

3rd Octet 255 - 248 = 7

4th Octent 255 - 0 = 255

Giving a wildcard mask of


(Kenneth B) #5

Hi Rene,

It looks like /25 - /30 were not written in the 4’th octet. That is where the masks should be written, correct?

Thank you,


(Rene Molenaar) #6

Hi Kenny,

Ah I see it now…that’s a copy/paste error, sorry for the inconvenience. It’s fixed now!


(Hoang T) #7

Hi Rene,
Are you going to talk about Wild Card and Access-List ?


Hoang Trinh