• # CCENT Subnetting Help

Hi All,

I am current taking the CCENT Course and I am viewing the video "Understand and apply subnetting Part 1 and 2"
and I am having a very difficult time following a particular subject in the video.

One of the examples is how do you make 8 networks with the provided IP below:

192.168.10.0

I understand how you start it, I understand converting it to binary. The part where I get lost is when they say we need 12 bits to make 8 networks. (How are they coming up with 12 bits)
Then in the video he goes with 3 bits? that does not make any sense to me?
00001100 (The one's being the 8 and 4 place holder value) wouldn't that be 4 bits(The last four digits being used

I don't understand that part, can someone assist

• My assumption is that I'm a poor communicator with a poor example. I probably thinking about another problem as I said something like that. It wasn't intentional.

So, let me try again, with the following:

To create the 8 eight networks, you must borrow 3 bits from the host bits portion, when you do, you first determine the new subnet mask.

I'm assuming I gave a subnet mask with the example. If we start with a 255.255.255.0 (default subnet mask for a Class C). I would only need to borrow 3 host bits. Which would mean 255.255.255.224 as the subnet mask. From that point. I would change the 4th octet to binary. Then within the 1st 3bits I borrowed, I would come up with every possible combination:

192.168.10.00000000 = 192.168.10.0
192.168.10.00100000 = 192.168.10.32
192.168.10.01000000 = 192.168.10.64
192.168.10.01100000 = 192.168.10.96
192.168.10.10000000 = 192.168.10.128
192.168.10.10100000 = 192.168.10.160
192.168.10.11000000 = 192.168.10.192
192.168.10.11100000 = 192.168.10.224

From there you should be able to determine the following for each network

• Network ID (above)
• range of usable IP addresses within each range
If I need an additional 8 networks, I must "steal" or "borrow" enough bits to create the 8 networks. This requires me ask how bit must I have to do so? 2^3 = 8 networks. So we borrow 3 bit and add that to the subnet mask= `255.255.255.11100000=255.255.255.224`.