Subnetting

Note:

Step 1: 1st we represent the / value in binary notation. calculate the CIDR value for New Subnet Mask (N.S.M).

Step 2: 1st we check how many on-bit in your IP-Address for example 195.168.10.1 this IP belongs to Class C and there is total 3-network and one host (N=24 bits, H=8 bits). 1st we check how many on-bit in your Host part not in network part. if there is any on-bits in your Host part then you put in formula
i.e. (2^on-bits)

Step 3: In this step we check how many off-bits in your IP address. for example: Total 8 off-bits & put these number of bits in formula
i.e. (2^off-bits-2)

Step 4: In Block Size we directly subtract your N.S.M with 256.
i.e. (256 - N.S.M)

Step 5: Range always start from 0. i.e. (0-255)

How to calculate Subnetting?

Q.1 Subnet the IP Address 195.168.10.0/24?a) How many subnet?b) How many host per subnet?c) What is block size?d) What is the range?e) What is the broadcast address?

Solution:

IP Address     =    195.168.10.0/24
Subnet mask  =    255.255.255.0 (class c)

In binary notation
11111111.11111111.11111111.00000000
New Subnet Mask  = 255.255.255.0

Number of Subnet = (2^on-bits)
                               = 20
                               = 1

Number of host/subnet = (2^off-bits-2)
                       = 28
                       = 256

Block Size = (256 – New Subnet Mask)
          = 256 – 0
          = 256

Range        = (0-255)

1st Subnet:
IP Address          = 195.168.10.0
1st Valid Host     = 195.168.10.1
2nd Valid Host    = 195.168.10.2
                                                   -
                                                   -
                                                   -
Last Valid Host   = 195.168.10.254
Broadcast      = 195.168.10.255


a) Number of Subnet = 1
b) Host/subnet           = 256
c) Block Size             = 256
d) Range                    = (0-255)
e) Broadcast address = 195.168.10.255