Subnet mask Calculation

Subnet Mask calculation:

1. Decimal Turn binary:

   Decimal:23-> 111,010 Binary

   2|23---1

   2|11---1

   2|5---1

   2|2---0
   2|1---1

   0

   Move the remainder from bottom to top, from high to Low: 10111

2. Binary goto decimal:

   Binary:11011-> 272 binary system

   1 (24) + 1 (23) + 0 (22) + 1 (21) + 1* (20) = 16 + 8 + 0 + 2 + 1 = 27

   From right to left, 2 of the N power operation, n increments from 0, and then multiplies each bit of the binary as a coefficient and the power operation result, and finally accumulates.

3. Amount of subnets (number of subnet numbers)

   2^ (32-Number of network digits-number of subnets)

4. Special Subnet Address

   The first address of the subnet (the host bit is all 0): indicates the network;

   The last address (host location is all 1): reserved for broadcast address;

5. Size of subnet (hosts)

   Sub-network bit number:

   The subnet mask is converted to 2, and it is all 0 bits in size;

   Subnet size = 2^ (number of subnet bits)

6. The legal size of the subnet (valid hosts)

   Subnet Size-2

   Special subnet addresses are not included in the number of legitimate hosts

7. Network number classification

   Class A: 0 0 0 start (binary), network number 8-bit

   Class B: 1 0 0 start (binary), network number 16-bit

   Class C: 1 1 0 start (binary), network number 24-bit

Subnet mask Calculation