Question About Subnetting/Todd Lammle CCNA book

Apr 05, 2006 2 Replies

Most relevant reply

Dude

Always substract 2 for your valid subnets. Only if they tell you ip-subnet zero is in use you don't subtract 2. Thats what they tell me to do on the CCNA exam.

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In Tom Lammle's book it seems as if the subnet chapter is a little confusing at times and this is why


1) At some times it seems that the practice problems assume ip-subnet zero is in effect, and that you do not subtract 2 from your total subnets to get your valid subnets. However, in his VLSM examples he does subtract 2 from his total subnets to get valid subnets


2) All of the subnetting sites always subtract 2 from your total subnets to get your valid subnets.



So that part that confuses me, is what should I do for the CCNA exam? Subtract 2, or always assume ip-subnet zero is in effect?



I am new to subnetting so this makes it even more difficult.. haha, I seem to be able to recall the info. Powers of 2, binary math, block sizes, etc. But I have a HUGE problem actually applying the information. When I am presented with actual problems I seem to forget everything and dont know where to begin.. ugh..



Any help would be mucho appreciated...



TIA



Always substract 2 for your valid subnets. Only if they tell you ip-subnet zero is in use you don't subtract 2.

Thats what they tell me to do on the CCNA exam.

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