Computer network—3 network layers (IP address and classification, subnet mask and subnetting)

table of Contents

1. IP address (32 bits), classification of IP address (ABCDE type), dotted decimal notation of IP address

2. The subnet mask of the IP address and how to divide the subnet

      0. The idea of ​​dividing subnets

      1. How to calculate the subnet mask?

      2. How to calculate the network address of the subnet?

      3. Default subnet mask

      4. Subnet division    (determine the network address according to the IP address and subnet mask)

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1. IP address (32 bits), classification of IP address (ABCDE type), dotted decimal notation of IP address

                  

                 

 

 

2. The subnet mask of the IP address and how to divide the subnet

0. The idea of ​​dividing subnets

IP address = network number + subnet number + host number

       

 

1. How to calculate the subnet mask?

Method: (the network number + subnet number are all 1, and the host number is all 0 )

Subnet mask length = 32 bits

A bit = 1: The corresponding bits in the IP address are the network number and the subnet number

A bit = 0: The corresponding bit in the IP address is the host number

 

2. How to calculate the network address of the subnet?

Use the subnet mask to find out the subnet part of the IP address

The IP address and the subnet mask are ANDed bit by bit to get the network address of the subnet. .

 

3. Default subnet mask

 

4. Subnetting

Calculation:

1) The number of subnets = 2 to the power of A-2 (A = the number of digits in the subnet number)

2) The number of hosts in each subnet = 2 to the power of B-2 (B = the number of digits in the host number)

 

3) Find the network address based on the IP address and subnet mask.