IP address is such an important knowledge that it's useless to listen to a younger student?

  

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Catalog

One .IP What's the address

  Two .IP The composition of the address

3、 ... and .IP Representation of address / Basic presentation

Four .IP Address classification --- Class addressing

  5、 ... and .IP Address type

  6、 ... and .IP Address calculation

7、 ... and . special IP Address

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One .IP What's the address

1.IP An address is like a real address , You can identify a node in the network , Data is used to find the destination , That is, we go through IP Address enables worldwide network communication , It can indirectly and abstractly understand the adult class Id card .

2.IP The address is the network device interface （ It is usually the interface between router and computer ） Properties of , It is not the attribute of the network device itself .

When we say assign one to a device IP Address time , In essence, it refers to assigning a IP Address .

If the device has multiple interfaces , Usually, each interface needs at least one IP Address

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  Two .IP The composition of the address

Network part + The host part of the =IP Address

Network part + The host part of the + Network mask = Complete and meaningful IP Address

Network part （ network number ）： The main function is to represent a network

The host part of the ： In order to distinguish which host is in a network

Network part

The host part of the

Network mask / Subnet mask ： The function is to distinguish IP Network part and host part in the address （ It can be roughly understood as 1 variable ,0 immutable -- Personal understanding ）

The network position represents where you are , The host location represents your specific location in the network host range

It can be understood that the network bit is like a rough address of your home （xx province xx City xx county ）, The host location is the detailed address of your home （xx community xx building xx unit xx House number ）

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3、 ... and .IP Representation of address / Basic presentation

1. The address we use now is usually IP v4（IP version 4） But now the overall trend is gradually to use IPv6 Start to change

2.IP The address is and the length is 32 bit, from 4 Byte composition .

3. For the convenience of reading and writing ,IP Addresses are usually expressed in dotted decimal numbers .

4.255.255.255.0 I could just write it as 24

5.IP v4 Address range ：0.0.0.0----255.255.255.255

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Now let's officially start our IP Addressing

 

Four .IP Address classification --- Class addressing

This picture needs to be remembered To remember memory ！！！

 

There's no need to memorize , In fact, there are simple memory methods

You can first think of the entire network segment as a rope

2 Of 8 Power =256, You can imagine that there are 256 A small knot , But because we are from 0 At first, so we finally thought it should be 255（ Sorry for the mistake in the picture , Should be 255）

We cut the rope （ notes ： Cut from the middle of the rest every time , The half after cutting is added to the group after cutting ）

The first shot ：256/2=128

Second knife ：128+（256-128）/2=192

The third knife ：192+（256-192）/2=224

The fourth knife ：224+（256-224）/2=240

 A/B/C The default netmask of class is 8/16/24 bit

Take the place where each knife is cut as the beginning of the network segment （0 With the exception of ）, Plus... Representing the starting range 0.0.0 And end range 255.255.255, I'll remember this watch soon

0~127 128~191 192~223 224~239 240~255

0.0.0.0~127.255.255.255

128.0.0.0~191.255.255.255

192.0.0.0~223.255.255.255

224.0.0.0~239.255.255.255

240.0.0.0~255.255.255.255

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  5、 ... and .IP Address type

Network segment ： The network range defined by a network number

network address ： Used to identify a network （ Like the name of the community , To prove that this is a network ）

 

Broadcast address ： A special address that can send data to all hosts in the network （ Well understood. , Radio ）

 

Available addresses : Addresses that can be assigned to other nodes of the network or network device interfaces （ Subtract network bits and broadcast bits from the network segment address ）

Be careful ：

1. The network address and broadcast address cannot be directly used by the network device on the interface , It can also not be used on other nodes

2. The number of available addresses in a network segment is ：2^n-2(n Represents the number of bits in the host part , reduce 2 Minus the network address and broadcast address )

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  6、 ... and .IP Address calculation

 

I don't know how to say , Go straight to the example and finish

  example ：172.16.10.1/16 This B Network address of class address 、 The broadcast address and the number of available addresses are ？

network address ：172.16.0.0

Broadcast address ：172.16.255.255

Available addresses ：2^16-2=65524

analysis ：

First look at the mask , yes /16 On behalf of 16 Bit network address and 16 Bit host address

32 Total mask -16 Bit network address = The host address

The network address is the starting bit of the network segment ：172.16.0.0

The last bit of the broadcast address segment ：172.16.255.255

Available addresses 2^n-2（n Is the number of host bits ）：2^16-2

example ： 192.168.1.0/24 Use a mask 255.255.255.240 Divide subnets , The number of available subnets is （ ）, The number of available host addresses in each subnet （）

by （ B）

A. 14 14 B. 16 14 C. 254 6 D. 14 62

analysis ： The mask represents network bits , Network bit immutable , The remaining hosts are in one network segment 256 Bit address

Number of subnets ：256/（256-240）=16

Number of available host addresses ：256-240-2=14（2 Network bit and host bit ）

example ： a IP The address is 10.110.9.113/21    The broadcast sent by the host at startup IP yes ？B

A.10.110.9.255 B.10.110.15.255

C.10.110.255.255 D.10.255.255.255

( This problem is not resolved , I don't quite understand , My own method can be written, but it is not guaranteed to be correct , I won't explain it in detail )

10.110.0000 1001.113

1   .   1.11111000

10.110.0000 1111.11111111

The broadcast bit is 10.110.15.255

example ： Plan a C Class network , The network needs to be divided into 9 Subnet , At most per subnet 15 Console host , Which of the following is the appropriate subnet mask ？D

A.255.255.224.0 B.255.255.255.224

C.255.255.255.240 D. No suitable subnet mask

because 256/9 Not an integer , Can't divide

example ： The address of a subnet segment is 5.32.0.0 Mask as 255.224.0.0 The Internet , The maximum host address it allows is ？C

A.5.32.254.254 B.5.32.255.254

C.5.63.255.254 D.5.63.255.255

Network segment address digits ：256-224=32

32+32-1=63

5.63.255.255 It's a broadcast bit -1 Is the largest host address

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7、 ... and . special IP Address

IP In the address space , There are some special IP Address

special IP Address	Address range	effect
Limited broadcast address	255.255.255.255	Can be used as destination address , Send to all hosts in this network segment （ Limited by gateway ）
Any address	0.0.0.0	“ Any network ” Network address of ; “ This host interface on this network ” Of IP Address
Loopback address	127.0.0.0/8	Test the software system of the equipment itself
Local link address	169.254.0.0/24	When the host fails to obtain the address automatically , An address in the network segment can be used for temporary communication