Do I have to memorize of 2 for CCENT subnetting ?

mustafa86m

I am wondering that if I should memorize power of 2 and how far show I go if I got a question about Class A network which is required too many host ,, any idea or help please guys .... Thank you

TechGuru80

You should memorize how to subnet yes. I would count on not being asked to subnet a large class A network.

mikeybinec

BLOCK SIZES! BLOCK SIZES! BLOCK SIZES!! They are all the same no matter which octet you are working in. And as for the 2^x, just recall that the number doubles as it moves from right to left i.e. 2^4=16 2^5=32 etc

networker050184

Just keep practicing and you'll memorize it before you realize.

OctalDump

Memorise at least to 2^8 or 2^10. It's easy enough to memorise the 4 digit ones (2^10 to 2^13).
Some people use the provided scratch page to write out the powers, subnet masks with CIDR.

You can get a rough idea for the others. Like 2^24 is 2^4 x 2^10 x 2^10 - roughly that's 16 x 1000 x 1000 or 16 million. You can also learn a couple at random and interpolate (like if you knew 2^16, you could work out 2^15 just by halving, or you can double 2^13 to get 2^14). Justing knowing that 2^10 is about 1000 gives you an idea of about where things should be.

If you have rough idea of those larger ones, it will probably help with any multiple choice you get where big numbers involved.

Also, just practice, practice, practice. It can be boring, but it doesn't take long to be able to do most of it in your head pretty quickly.

mustafa86m

I really appreciate your replies guys , that what I was talking about , if I have like 2^24 or 2^23 , the only way is to double the previous number. Thank you

bender_fender100

Repetition, repetition, and more repetition. Think of it like learning your multiplication tables again. At first subnetting seems hard, but doing it over and over, writing out what each value is in binary, and writing out the different masks and values a lot of times is what really helped me to get it down to the point where I can write everything out before taking the test from memory, especially from /25 to /30, which I really stress that you get those down pat so you can figure out the others pretty easily from there. Also for the powers, I took the same approach there of writing out whole blocks of data over and over and I'm able to remember from my head that 2^12 is 4096 for example and I can figure out the other ones after that by doubling it each time.

It also really helps to understand the logic of it before you learn the shortcuts. I think what also helps is being able to understand different approaches to doing the subnetting problems and finding which one works best for you.

I'm glad you're starting to get it.