Subnetting exam question

Is there a short way to figure out how many subnets or hosts there are with a particular subnet mask when using the formula 2^s? I guess what I am asking is, Will they let you use a calculator to figure out what 2^22 equals?

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Comments

pooker

No calculators, its simple math, the exam cram books come with a chart for easy memorization of you need something of that nature.

dynamik

I think 22 is a pretty large number, and you're not going to be asked to do that on the exam. You might want to just memorize the values up to 10 or 12. Even if you just remember that 5 is 32 and 10 is 1024, and that one step up is twice the previous amount, and one step down is half the amount, you can figure out pretty much any realistic number in a couple of steps.

i.e. 10 is 1024 so 11 is 2048 (twice the amount) and 9 is 512 (half the amount).

You could always double your way up 22. With just a pad and paper, this shouldn't be too bad.

jcblester

Thanks for the info! I happen to be on that chapter in the Odom book and kinda paniced a bit. It seems a little overwhelming at the moment, but I have not had a chance to practice enough to commit to memory. Thanks for the reply I am sure I will have plenty more ?'s in the near future.

Project2501

Practice workbook I was given in my cisco cause at TAFE.

It shouldn't take you to long to finish. I think from memory all examples are classfull but that wont hurt.

It helped me.

jcblester

Thank you so much for the workbook link! I know this will help me out alot!

Picker

This is very brilliant

Kalabin

I always have a scratch piece of paper on me, then at the very bigging jot down the following.

2^1 = 2 (zero usable)
2^2 = 4 (two usable )
2^3 = 8 (six usable )
2^4 = 16 ( 14 usable)
2^5 = 32 (30 usable)
2^6 = 64 (62 usable)
2^7 = 128 (126 usable)
2^8 = 256 (254 usable)
2^9 = 512 (510 usable)
2^10 = 1024 (1022 usable)
2^11 = 2048 (2046 usable)

so 2^3 in binary would be 11111111.11111111.11111111.11111000
Which then equals out to 255.255.255.248

First IP is used for network, last usable is for the broadcast.

It's just a matter of looking at the bit's borrowed. It seem's to work for me, but like I said I write all my formula's down right at the beginning of test's. Much like ohm's law's PIER formula.

E over P = R, E over R = P, P * R = E, etc. Quick formula for converting amps, voltage, resistance.

E (squared)
----
P | R

E
---
I | R

P
---
E | I

P
---
R | I (squared)

mikearama

Oh man, jc... play the binary game. There's no easier/funner way to learn subnetting than playing the game.

Log into the CCNA Prep Centre:
http://forums.cisco.com/eforum/servlet/PrepCenter?page=main

Click on the Games Tab.

Start with the Binary Game. Then do the Subnet Game. They've added a new multiplayer game... now I just gotta get a friend.

Mike

Don 79 TA

dynamik wrote:

I think 22 is a pretty large number, and you're not going to be asked to do that on the exam. You might want to just memorize the values up to 10 or 12. Even if you just remember that 5 is 32 and 10 is 1024, and that one step up is twice the previous amount, and one step down is half the amount, you can figure out pretty much any realistic number in a couple of steps.

i.e. 10 is 1024 so 11 is 2048 (twice the amount) and 9 is 512 (half the amount).

You could always double your way up 22. With just a pad and paper, this shouldn't be too bad.

this is the approach i plan on taking

Taisia

I created an A4 Subnet calculator and hope people can memorise it for use in the exam

Are we allowed external links here

http://rapidshare.com/files/98826391/Ultimate-Subnet-Calculator.rar.html

Rar file contains 1 pdf file (6 pages)

Please feel free to repost this A4 Calculator anywhere else you wish. I created it and it is freeware.

Soha|L

can anyone refer any gud site tht offers subnetting questions...??

m doin questions from www.subnettingquestions.com, but they r pretty much straight forward...

dynamik

sohailq wrote:

can anyone refer any gud site tht offers subnetting questions...??

m doin questions from www.subnettingquestions.com, but they r pretty much straight forward...

You could try www.learntosubnet.com

Soha|L

thanx for the help