Article directory
1. Overview of TCP/IP
1. TCP/IP protocol family
- A communication rule that must be followed when computers communicate
- A collection of the most widely used communication protocols
- Includes standard protocols in a large number of Internet applications
- Support cross-network architecture, cross-operating system platform data communication
2. Three elements of host-to-host communication
- IP address
- subnet mask
- IP routing (default gateway)
2. What is an IP address
1. An Internet address used to identify a network node (like a telephone number)
2. Composition of IPv4 address
- Address length: 32 bits
- 4 decimal numbers (0~255), separated by ., called "dotted decimal method"
3. IP address classification
1. Commonly used IP addresses
- Class A 0~127 super large network . main. main. main
- Class B 128 ~ 191 large network network.net.main.main
- Class C 192~ 223 small and medium network network.net.net.main
注意：IP地址由网络地址和主机地址两部分组成，所以上面会标有"网"、"主"字样。以座机号码为例：网络地址相当于区号，主机地址相当于电话号码。如下图所示。
The range of IP addresses from class A to class C is shown in the following figure:
2. For multicast and scientific research
- Class D 224~239 multicast
- Class E 240~254 Scientific research
4. IP address classification (continued)
According to the scope of use
- Public address: It can be used legally on the Internet, and it needs to be paid to NIC for application. It is unique in the world
- Private address: reserved for internal use of the enterprise, free of charge, unique in the LAN . The private IP address range is shown in the figure below.
5. What is a subnet mask
- Determine the network bit of the IP address, and the IP with the same network bit can communicate directly
- Cannot exist alone, must be used together with IP address
The default subnet masks of various IP addresses are shown in the figure below:
6. What is a gateway
- A "gateway" from one network segment to another
- Usually the address of a router or firewall/access server
The schematic diagram of the gateway is as follows:
7. How to view IP address parameters
There are two ways to check the IP address parameters.
1. Right-click the win icon in the lower left corner of the desktop, select Settings in the pop-up list , enter the setting page, select Network and Internet , then select Ethernet , and finally click the network connected to the machine to see the detailed IP address parameter.
2. Press the win+R key at the same time to call out the run box, enter cmd to open the console, enter the ipconfig command, and press the Enter key to see the IP address information.
注意：输入 ipconfig/all 命令可以查看更详细的DNS服务器、物理地址等信息，如下图所示。
8. Test network connectivity
ping command
- "Throw stones to ask for directions" to the target host, and judge the network connectivity based on the feedback results
If the network is normal, it will display the words "Reply from ...: byte =, time <" and so on as shown in the figure above; if the network is not connected, it will display the words "...cannot access the target host";