Subnet trick...

PCHoldmann

This is good for Cisco exams, and work, if you ever need to figure out subnets on paper.

To figure out the valid addresses in a subnet:
Take the octet that is not 0 or 255 and subtract that value from 256 - i.e. 256 - 224 = 32. Now make a chart starting at 0, and adding the value from that last step with each line (the note board I got for the CCNA had gridlines, which made it even easier)

  0
 32
 64
 96
128
160
192
224
256

Now, leaving room in between, write on each line the value of the line below, minus 1

  0		31
 32		63
 64		95
 96		127
128		159
160		191
192		223
224		255
256

The values on the left are the valid subnet addresses, and the right is the broadcast address.

If you want, now fill in the valid ranges in between

  0	1-30		31
 32	33-62		63
 64	63-94		95
 96	97-126		127
128	127-158		159
160	161-190		191
192	192-222		223
224	225-254		255
256

There you go, all your addresses, with subnet and broadcast addresses.

(Sorry for the formatting)

Fu Loser

Thats the most simple explanation for that trick I have seen!

Thanks!

ThanatosKnight

Can I ask you what kind of practice tests you did for the exam ?

I'm currently doing the netsim labs included in the cisco press books(wendell odom) , I also did the cisco press simulation exams (intro cd e icnd cd) and some questions on the trascender demo .

Thanks a lot

PCHoldmann

I used the same Cisco press tests, and also the PrepLogic tests that came with the ExamCram2 book, along with the practices on www.ExamCram2.com(the CCNA test is based on the last version, but still help). And used the practices on this site, of course! I also looked around on the internet for demo, but I don't remeber which ones I found. I like the Cisco Press ones, but I warn you the sims are more involved on the test!

HTH

Peter

Sulblk27

Thanks for the new way of lookking at subnetting....just when I think I had it down cold- I wind up stumbling over the process of getting the right subnets!

I am looking to purchase the cisco press learning kit, are there any other simulators I can get that would be comparable to the test sims?
Thanks in advance

ThanatosKnight

Infact , I'm doin' the boson router netsim labs (learnig edition), because the sims on the cisco press tests are not difficult .

The labs are well done ... Infact , It's possible to do some troubleshooting
and the configurations are related to different network devices ... So you have to do the things with all in your mind and when everything works it gives you a lot of satisfaction... Isn't It ?

Thanatos

rconsole

You may also try RouterConsole simulator; I believe the free version can be useful for any CCNA candidate.

Good luck!

RigsVille

Thankd for the info - I've been told this technique before but never fully understood it, now I do!

Thanks for the posting.

-- Rig
www.RigsVille.org.uk

Promedia-77

That is a nice trick , although it is very old to be honest, with all due respect. You guys should check your cds you get with your ccna books. And for the CCNA exam, you need to be really fast on your IP questions. Know all the magic numbers as well, you only have about 1 minute and 30 seconds for each question.

medic

Magic numbers?