Subnet (dotted decimal to bit count) Description

Subnet (dotted decimal to bit count)

How to convert a subnet which is in  dotted decimal into a bit count?

Suppose we have a subnet value which is 255.255.255.224 and can be written also as 27 in bit count value. So to convert it here are the following steps. 

We know that a 255 bit value is equal to 8 so if we add 8 bit each for 255.255.255 we will get 24.

Now the remaining bit which is 224 bits left in the dotted value can be calculated as shown below 

First Write the table as shown below 

128        64        32        16        8        4        2        1 

Now start calculating the sum of the table which will be equal 224 from the left side like this  

128        64        32        16        8        4        2        1  

 1         1       1      0      0      0      0     0   

  

so now we have filled 128, 64 and 32. If we add the values of the  three numbers we will get 224. It means 3 is the bit count for 224, so

255.255.255.224

8 + 8 + 8 + 3 =27 

                                        

Here are some other questions with solutions for you to understand and practice 

1) 255.255.255.252

Sol

Now first add the 255 bit value which is equal to 8 and the total we get is 24

Now convert the remaining value using the table 

128        64        32        16        8        4        2        1 

 1            1          1         1          1        1        0        0

Now after converting the remaining value we get the value which is
6 so

255.255.255.252
     8 + 8 + 8 + 6   = 24

2)255.192.0.0

Sol

Now first add the 255 bit value whic is equal to 8 and the total we get is 8

Now convert the remaining value using the table 

128        64        32        16        8        4        2        1 

 1            1          0          0         0        0        0       0

Now after converting the remaining value we get the value which is
6 so

255.192.0.0
8 + 2 + 0 + 0   = 10

3)255.255.128.0

Sol

Now first add the 255 bit value which is equal to 8 and the total we get is 8

Now convert the remaining value using the table 

128        64        32        16        8        4        2        1 

 1            0          0          0         0        0        0       0

Now after converting the remaining value we get the value which is
1 so

255.255.128.0

8 + 8 + 1 + 0   = 17

4)255.255.255.240

Sol

Now first add the 255 bit value which is equal to 8 and the total we get is24

Now convert the remaining value using the table 

128        64        32        16        8        4        2        1 

 1            1          1          1         0        0        0        0

Now after converting the remaining value we get the value which is
4 so

255.255.255.240

8 + 8 + 8 + 4  = 10