Analyze basic knowledge and basic operations of IP addresses in detail

1. Concept of IP Address
 
In order to allow two computers on the network to communicate with each other, people assign each computer an ID address similar to the phone number in our daily life, that is, an IP address, it is transmitted as additional information in the data packet. IP addresses are composed of 32-bit binary numbers and are unique over the Internet. For ease of memory, the IP address is divided into four segments, each of which is separated by a decimal point, and then replaced with a decimal number. This becomes our common example: 202.112.42.79.

When using an IP address, note that the IP address cannot start with a number 127, and the number 127 is reserved for the internal return function. The first byte of the IP address cannot be a broadcast address of 255,255; the first byte of an IP address cannot be "0", and "0" indicates that the address is a local host and cannot be transmitted. The IP address must be unique in the same network;

2. Recognize the subnet mask

The subnet mask is used to determine whether the IP addresses of computers belong to the same subnet. That is, after the "And" operation is performed by the IP address And subnet mask, if the result is the same, the two computers are in the same subnet And can communicate directly. For example, the IP address is 192.168.0.1 and the subnet mask is 255.255.255.0. Convert to binary: IP Address: 1102.16.10101000.20.0000.00000001, subnet mask 11.11.00000000. The so-called "And" operation is the result of "And" 1 And 0 "And" 0 "And" 1 "And" 0, therefore, the result after "And" is: 111000000.10101000.00000000.00000000, converted to decimal And then 192.168.0.0.

3. Basic IP maintenance operations

1) Ping

This command is used to check whether a route can be reached and to quickly check whether the site you want to visit is accessible. If Ping fails, the problem may be: network connection, network adapter configuration, and IP address availability. If the network service is still unavailable after Ping, the problem may be caused by network software settings.

Format: ping-t-a-n count-l size. parameter description:-t allows the user's host to continuously send data to the target host, -a displays the network address of the target host in the IP address format.-n count specifies the number of ping attempts, and the count parameter specifies the number of ping attempts, -l size indicates the size of the data packet sent to the target host.

2) winipcfg/ipconfig

Winipcfg/ipconfig is used to display the specific configuration information of the IP protocol. If the winipcfg/ipconfig command is run without any parameters, the program displays the physical address, Host IP address, subnet mask, and default gateway of the network adapter in the window. You can also view the host name, DNS server, and node type.

For Win95/98 winipcfg), Win2000/Xpipconfig), format: winipcfg /? /All ,/? The format and parameters of winipcfg/ipconfig are displayed in English./all displays all IP address configuration information.

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