SUBNETTING MADE EASY

When people are learning subnetting and see what needs to be done, it can sometimes seem overwhelming and complicated. Learning classes and standard subnet mask then borrowing bits, learning values to create the new subnet mask, knowing which octet to subnet in correctly. Well I'm glad to say that there is a process of subnetting that makes it extremely easy to complete successfully. Theres no binary math involved or converting decimal to binary. Knowing your classes and standard subnet mask with proper value placement of an 8-bit octet is sufficient knowledge. Here's how you subnet a standard class C private address (pa) of 192.168.0.0/28

1. First you know that the standard class C subnet mask has 24 bits turned on for your network, so your standard sn (subnet) mask is 255.255.255.0

2. Second, you need to determine how many bits you are subnetting with and in which octet: if 24 bits is a standard C which is 3 octets and you have 28 bits turned on in the subnet mask then you simply do this (28-24=4 ** 28 being your bit mask and 24 being your standard subnet mask for a class C address). So you have 4 bits turned on in the 4th octet used for subnetting and the other 4 bits will be used for your host which will occupy all 32 bits.

3. Third, you take your IP address and your new subnet mask which is 255.255.255.240 and make a 6 row 2 column chart listing the IP address and the subnet mask as the first two leaving space for the Resident Subnet (Network or Subnet ID, or Network Group etc...whichever you would like to call it), the 1st usable address, the last usable address, and the broadcast address.
IPv4 Address: 192.168.0.0
SN Mask : 255.255.255.240
1st Subnet :
1st Address :
Last Address:
BC Address :

4. You then take the interesting octet(the octet being subnetted) of the subnet mask and subtract it from 256 (256-240=16). Which here gives you 16, this is going to be your base value of your subnets. Starting from 0 you count to 256 by 16's (0-16-32-48-64-80-96-112-128-144-160-176-192-208-224-240-256) and these are all of your subnets except for 256 because you would be going into the next bit borrowed.

5. So your first subnet is 192.168.0.0 which goes into row 3 of your chart and your broadcast address is minus 1 of your next subnet (and remember you are subnetting in the 4th octet) which goes in the 6th row

IPv4 Address: 192.168.0.0
SN Mask : 255.255.255.240
1st Subnet : 192.168.0.0
1st Address :
Last Address:
BC Address : 192.168.0.15

6. Finally, to find your range of usable addresses you simply add 1 to the Resident Subnet for the 1st address and subtract one from the broadcast for your last usable address which gives you your range of usable addresses

IPv4 Address: 192.168.0.0
SN Mask : 255.255.255.240
1st Subnet : 192.168.0.0
1st Address : 192.168.0.1
Last Address: 192.168.0.14
BC Address : 192.168.0.15

This is your first subnet with 192.168.0.0/28. You figured out the new subnet mask, range of usable addresses and the broadcast address. Also you now know all of your subnets with this scenario with 192.168.0.16 being your next subnet