I am not sure who has written this.. just found on net...when I saw few posts here regarding subnetting then really wanting to share this great stuff with you all.... Now I can easily do subnetting by using this method.....Enjoy...
You think Subnetting is a beast?
You think you have to be Superbrain to understand it?
You are wrong!
Here the step-by-step course.
After reading and some self-training, you should be able to fix Subnetting-Questions in CCNA Exam
without any problems in a snatch.
What is a Subnetmask?
With Subnetmasks, we can divide an IP-Address in network-part and in host-part.
A given IP-Network can be divided in smaller parts. Each of this smaller parts is called a "Subnet".
If we for example have the network
We have here ONE Class C - network, with 253 useable IPs for Client-PCs.
The useable IP Range of this network is
192.168.10.1 - 192.168.10.254
The very last IP of each Subnet is called Broadcast-Address.
This address is in that example 192.168.10.255 and its NOT useable for host-pcs.
If we want to divide this network in two parts, we must use subnetting.
With Subnetmask 255.255.255.128 we would divide the network in two parts.
Here some examples of real exam questions, and step by step solutions:
Given that you have a class B IP address network range, which of the subnet masks
below will allow for 100 subnets with 500 usable host addresses per subnet?
Allways the same game... Like in 5 minute course..
Power of 2 that is minimum 500?
Now - put the last 9 Bits of your Subnetmask to "0"
That is in decimal
If a host on a network has the address 172.16.45.14/30, what is the address of the
subnetwork to which this host belongs?
/30 means 11111111.11111111.11111111.11111100
The last of the ones stands under the "4". That is our increment or network jump.
172.16.45.0 - 172.16.45.3
172.16.45.4 - 172.16.45.7
172.16.45.8 - 172.16.45.11
172.16.45.12 - 172.16.45.15
172.16.45.16 - 172.16.45.19
As we see, the Ip is in the Range of 172.16.45.12 - 172.16.45.15.
So the network Address is 172.16.45.12
QUESTION NO: 9
Which two of the addresses below are available for host addresses on the subnet
192.168.15.19/28? (Select two answer choices)
F. None of the above
/28 means 11111111.11111111.11111111.11110000
The last 1 stands under the 16. This is increment or network-jumps.