basic subnetting troubles

chehorn

This could just be in issue with me not understandingsubnetting fully. I am following the CBT nuggets series and have been practicing subletting but a few problems throw me off. For example When trying to get 200 networks in a class a ip, i see that it will take 8 bits to reach that number so we need 8 additional bits are added to subnet mask making it /16. What I'm having trouble with is finding the bit range for the range of subnets. From what I remember you take the last bit column and use iys value. For example /18 would be 64. But I. This scenario I am given 1...pretty confused any help would be great.

tecnodog7

Suppose we have a networking 192.168.0.0 with a sub net mask of 255.255.0.0 and we need to get 200 network.

First lets convert 200 into binary
200 = 11111111 = 8 bits

Now lets convert 255.255.0.0 or /16 into binary.
11111111.11111111.00000000.00000000

Now let's start adding network bits where its needed
so the new binary is
11111111.11111111.11111111.00000000
Now let's take the smallest interval which is a 1. (How did i get this? 128,64,,32,16,8,4,2,1)

Now that we found for smallest binary value how lets find the range.
192.168.0.0 -192.168.0.255 (To not here we only have 254 usable host 0.0 network , 0.255 bcast
192.168.1.0 -192.168.1.255
192.168.2.0 - 192.168.2.255
And so now. So let's find out how many network we have
the easiest way to do that is 2^n (n being your network bit) so if we do this 2^8 = 256

Hope this helps

CCIE Wanna Be

This is an older thread, but it may help you.


http://www.techexams.net/forums/ccna-ccent/38772-subnetting-made-easy.html

chehorn

Of course! Thanks for laying it out so nicely for me, makes complete sense now. Was way over thinking it. Appreciate the quick response.