Fast Subnetting For Exam

Hi guys,

I'm new here, after a quick search on these forums I couldn't find what I was looking for.

Basically I'm going for the 802 exam in a few months, and I've been told that time should be valued during the test and you should be able to pretty much subnet off the top of your head.

I completely understanding subnetting but not too confident that I can answer questions lightning fast.

I was thinking as soon as the exam started I could very quickly write down the following table or something similar (perhaps with another column including amount of subnets available):

Would this be a good idea to save time? What's your technique? I'm guessing converting to binary is out of the question

Any advice would be very much appreciated, and I'm sorry if it has been covered before.

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Comments

remyforbes777

If you can remember all of that then you can probably learn how to do subnetting in your head. Its easier and quicker.

mikej412

Todd teaches subnetting -- the "easy way" -- in the Sybex 6th (and earlier) edition. The link to that (and www.subnettingquestions.com and www.learntosubnet.com) are in the CCNA FAQ.

It is a good idea to have a "backup subnetting chart" that you are comfortable with that you can write down on your dry erase marker board before the exam (during the Exam Tutorial and NDA) -- just in case.

Links to the Cisco Exam Tutorial and the Cisco Non-Disclosure agreement are also in the CCNA FAQ -- read them now so that you can use the time before the exam for other things -- like jotting down notes, or just getting to the exam that much quicker.

dredlord

The 3 step process taught in the CBT nuggets videos is excellent you can work out a subnet question in about 1min

I HIGHLY RECOMMEND It as it taught me subnetting

wolverene13

This is my chart that I use, I think it's the easiest one to use:

CIDR - /25 /26 /27 /28 /29 /30 /31 /32
Mask - .128 .192 .224 .240 .248 .252 .254 .255
Total hosts - 128 64 32 16 8 4 X X
Useable hosts - 126 62 30 14 6 2 X X
# of Subnets - 2 4 8 16 32 64 X X

It would be good to just learn to subnet in your head, but it wouldn't hurt to write something like this down.

kevin31

How does the above table work then?

wbosher

I agree with dredlord, the cbtnuggets way is really easy. I can now do it in my head in about 30 seconds! Also do plenty of practice on subnettingquestions.com