wendell odom - subnetting

steveo1985

Just bought his books, as using only lammle's book wasn't working for me.

I have one thing to say, it contain's much more detail and focus's on the 2950 router, lammle use's both the 2950 and the 1900 router example's. Im finding the different take on the subject a breath of fresh air as it make's it easier to take the information in.

I have one problem though. The Boolean AND theory to find out subnet number and broadcast for an address? is it needed? when you can use the block size theory?

E.g. 130.4.102.1 with a mask of 255.255.252.0

block size of 256-252 = 4

4x25 = 100

subnet is 100
Range is 101 - 102
broadcast is 103

with the next subnet being 104.

answer 130.4.100.0

in the Odom book he explains this as a long process instead of 256 - X

e.g.

address 130.4.102.1 1000 0010 0000 0100 0110 0110 0000 0001
mask 255.255.252.0 1111 1111 1111 1111 1111 1100 0000 0000
AND result 1000 0010 0000 0100 0110 0110 0000 0000
= 130.4.100.0

Is there any need to learn the odom way? or will i find it useful on harder subnetting questions?

any ideas?

dtlokee

I would subbest knowing how to do it every way, but in application on the exam you need to be fast, really fast. If you take the time to convert to binary, and all the other steps you'll run out of time. You will find the block values to be much faster, but be careful because lots of people make mistakes in their addition.

rakem

i hate the AND way... never really could grasp it properly...

after prastice you can normally just look at a address and mask and figure it out in your head.

but it always helps to write the mask out in binary and do the good old 256 - x formula to get the block size.... once you have the block size everything else is easy