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Sunetting and memorization
mog27
Member Posts: 302
in CCNA & CCENT
Hi, I am looking through the latest Sybex book and it recommends memorizing the CIDR notation masks, block sizes, bits, etc. Is that really necessary? To me it seems like knowing your power of 2's and knowing how to subnet is what you need to know. It would make subnetting a lot faster memorizing block sizes, bits and CIDRs, but for the exam how fast do you have to be and won't you be able to use scrap paper to do the math? What do you all recommend? Thanks
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networker050184
Mod Posts: 11,962 Mod
Once you practice enough you will memorize it. Knowing what a /28 is will be like second nature eventually. Just work with it and it will stick.An expert is a man who has made all the mistakes which can be made. -
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jvrlopez
Member Posts: 913 ■■■■□□□□□□
You'll have a laminated piece of paper that you can use a dry erase marker on. I did 100 subnetting questions a day while studying for the exam but still wrote down my powers of two and formulas for networks and hosts on the paper before starting (do this during the tutorial since your exam's clock isn't running then).
I used the Sybex book as well and didn't bother memorizing all the metrics of each CIDR for every class as it recommended. I thought that was overkill. All I remembered were my powers of two, block sizes, and formulas for # of networks and # of hosts.
It helped a lot to remember that 4 bits on in an octet equals a block size of 16 and work "up" or "down" from there.
It will help greatly if you practice your subnetting repeatedly before taking the exam. Given the limited amount of time you have on the exam, you don't want to be caught up on a math problem.And so you touch this limit, something happens and you suddenly can go a little bit further. With your mind power, your determination, your instinct, and the experience as well, you can fly very high. ~Ayrton Senna
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Technoracer
Member Posts: 105 ■■■□□□□□□□
Great site to help you practice subnetting, and eventually memorize it: subnetting.net - Subnet Questions and Answers -
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olaHalo
Member Posts: 748 ■■■■□□□□□□
I didnt memorize them for the exam.
But I could convert from CIDR to binary to mask very easily. -
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Xyro
Member Posts: 623
...but for the exam how fast do you have to be...
Very fast
It is the subnetting that will get you because if you are not very fast it will eat up your time.