Video link: https://www.bilibili.com/video/BV1Lf4y1t7Mc?p=8-13

IP address details

ip address is a unique identifier, which is a network code

LAN

LAN: generally called intranet

LAN composition: switch, network cable, PC

Switch: a device used to form a local area network of an intranet

IP address

32-bit binary

Hexadecimal: x.x.x.x ------ the range of X is 0-255

Subnet mask

LAN communication rules: in the same LAN, you must be in the same network segment to communicate with each other!

Composition of IP address: network bit + host bit (IP address with the same network bit is the same network segment)

How the subnet mask determines the network bit: the number corresponding to 255 is the network bit, and the number corresponding to 0 is the host bit

IP address details

ISO defines address classification: five categories (distinguished by the first bit of IP address)

Class A: 1-126 bits default subnet mask: 255.0.0.0

Class B: 128-191 bits default subnet mask: 255.255.0.0

Class C: 192-223 bits default subnet mask: 255.255.255.0

Class D: 224-239 multicast address

Class E: 240-254 for scientific research

Note: we can use it at present A.B.C Class subnet mask can be modified
127.0.0.1 Represents the local loopback address

The addresses of each network segment are divided into three categories:

1. Name of the network segment: all host bits are 0

2. Broadcast address of the network segment: all host bits are 1

3. Available addresses: (all host bits are 0 --- all host bits are 1), open the set, excluding both ends

Example:
Q: 10.1.1.1/24 Which network segment does it belong to? How many network segments are available IP Address? What is the broadcast address of this network segment?
Answer: according to the question, the network bit is 24 bits, and the last 8 bits are the host bit
	10.1.1.1 Belong to 10.1.1.0 Network segment
	10.1.1.0 Network segment available IP The address range is: 10.1.1.1-10.1.1.254
	10.1.1.0 Broadcast address of network segment: 10.1.1.255

gateway

Gateway: the exit of a network. Generally, the gateway is on the router

Router: a device that can be used to connect internal and external networks

pc Outsourcing:
1.First judge the target IP Are you in the same network segment as yourself
2.If it is in the same network segment, it will be sent directly without finding a gateway
3.If it is not in a network segment, it will be contracted to the gateway

DNS Domain Name Service

1.local DNS cache
2.local hosts file
3.look for DNS service

Binary conversion (omitted)

Network test command

First: start - run - enter cmd - enter the command line window / win+r to open the run window

How to view IP addresses

ipconfig # view basic IP address information

ipconfig /all # view IP address details

Test network connectivity

ping the target IP address # to test the network connectivity. Successful communication can be achieved if there is going and going back!

ping - tdestination IP address # has been ping

ping -n digital destination IP address # modifies the number of ping packets

Note: if ping No, maybe the other party is not online, or the other party has a firewall on!

Resolve domain name manually

nslookup www.baidu.com # manually resolve the IP address of the domain name

DOS command

Clear command window

cls                 #Clear screen

Commands related to directory folders

c:/d:/E: # switch drive letter

dir # browse the file contents of the current folder

dir route		//Browse the contents of the file at the specified path location
dir /a 		 //Browse everything in the current location, including hidden files	

cd # switch position

cd 	Folder name	  //Enter the folder tab key to complete the path function
cd ..			//Go back to the previous directory
cd \			//Go back directly to the root directory

md # create folder

md	Folder name		  //Create folder name
md a,b,c 			//Create multiple folders at the same time
md d\e\f 			//Create multi tier folders at the same time

rd # delete folder

rd Folder name 		//Delete empty folder
rd Folder name /s 		//Delete the non empty folder
rd Folder name /s /q 	//Silent deletion of non empty folders
rd . /s /q		   //Delete all files in the current directory

File related commands

create a file

Create file method 1: echo
echo character string >>[route\]file name.Extension
 notes:>>and>You can input the output of the command into a file. If the file does not exist, the file will be created at the same time 
>>For append 		//Add text at the end of the original document
>For overlay 		//Empty the contents of the original file and add text to the file again.
Case: modification hosts file echo 1.1.1.1 www.baidu.com >>D:\b\www222.txt

Create file method 2: copy
copy con file name.Extension
 Start writing content
ctrl + z 	Press enter to finish writing

type browse the contents of the file

type file name.Extension 		//Browse the contents of a file
type file name.Extension |more	//Pagination display

del delete file

del file name.Extension 		//Delete file 
del *.txt 				//Delete all files ending in txt 
del *.* 				//Delete all files 
del *.* /s /q 			//Delete all files without prompting 
notes:*Is a wildcard, representing any character and any length

Move / copy / rename files

Copy file: copy [route\]Source file full name destination path[\Full name of new file] 
Move files: move [route\]Source file full name destination path[\Full name of new file]
Rename file: ren [route\]Source file full name destination path[\Full name of new file]

Shutdown and restart

shutdown -s -t second 		//Timed shutdown 
shutdown -s -f -t second 	//Timed forced shutdown 
shutdown -r -t second 		//Timed restart, the same as above, plus - f, is forced restart 
shutdown -a 			 //Cancel timing 
shutdown -l 			 //Logoff is the same as logoff command.