There is also the inability to connect online! Supplement:
It is useless to change the mantissa of IP address n times (system error always pops up). The IP address conflicts with other systems on the network.
There is also the inability to connect online!
What if the IP address conflicts? How to resolve IP address conflict
In the same LAN, if two users use the same IP address at the same time, or one user has obtained an IP address through DHCP, while other users set the same IP address through manual allocation, it will cause IP address conflict, which will make one user unable to use the network normally.
2. Sometimes, when the administrator or user sets the parameters provided by the administrator, there will also be cases where the parameters are input incorrectly due to mistakes;
3. The most common problem is that maintenance personnel use temporary IP address application when maintaining and debugging clients;
4. It is not excluded that someone steals someone else's IP address, resulting in IP address conflict.
Solution of IP address conflict in LAN;
Option 1: check one by one.
This is the most primitive method, that is, when there is an IP address conflict, check next to each computer in the LAN, and modify the IP address after finding the computer that conflicts with it. However, this method is time-consuming and not suitable for large-scale LAN, but only for small-scale network environment.
Scheme 2: MAC address binding.
1. Check the MAC of the local computer and bind it: You can know the MAC address of the network card by running Winipcfg.exe or Ipconfig.exe on the local computer system. The details are as follows: Click Start in Win9X system in turn, enter Winipcfg in the text box, and press Enter to pop up the IP configuration window. Select PCI Fast Ether Adapeter from the drop-down list, and the text displayed in the address bar of the adapter is the MAC address of the network card; Run the ipconfig command with all parameter at the DOS prompt of WinNT system, that is, ipconfig/all can also display the MAC address of the network card.
2. Remote detection of MAC addresses of computers: For network administrators, sitting in front of their own computers, they can use TCPNetView tool software to detect the MAC addresses of all computers in the local area network. After the software is installed, execute tcpnv.exe to display the main window of the program. Select the refresh command in the file menu or press F5 directly to start scanning the existing computers in the LAN, and then the computer name, IP address and MAC address will be displayed. When you get the MAC address of a computer network card, you can record it and configure it on the gateway or firewall through network management. The specific binding command varies depending on the gateway or firewall used. At this point, if other computers want to use the bound address, there will be a prompt that the IP address has been used.
Scheme 3: Switch security port.
In the past, routers and hubs were used in the network, but now many local area networks have been replaced by switches. With the sharp price reduction of switches in recent years, switches occupy a dominant position in the network market, mainly because of their high cost performance, flexible structure and flexible configuration with the changes of future applications. For the IP address conflict, different departments can also be isolated by using the port of the switch, because different areas can be managed differently by using the switch, and the divided network segments do not interfere with each other, which can solve the problem of IP address conflict to a certain extent.
Option 4: VLAN Division.
Although you can use switches to isolate network segments, thus avoiding IP address conflicts to some extent, it still cannot prevent IP address conflicts caused by user configuration errors in network segments under the same port. A better solution is to use switches to divide VLAN, and then use MAC address binding to deal with them comprehensively.
Solution of personal IP address conflict
1. If the operating system of your computer is windows 98.
Click Start → Run in the lower left corner, type: winipcfg, click OK, click Release All in the pop-up window, and then click Update All to solve the IP address conflict problem.
If you are prompted that you cannot update, you need to restart your computer.
2. If the operating system of the computer you are using is windows 2000 or windows XP.
Click Start → Run in the lower left corner, type: ipconfig /release, click OK, click Start → Run here, type: ipconfig /renew, and click OK to solve the IP address conflict.
How to solve the ip address conflict?
IP address conflict resolution:
First, the IP address of the computer under the router is different from the IP address of the conflicting computer, which can be solved by changing the IP.
Right-click My Network Places->; "properties":
Pop up the network connection management window, and right-click Local Area Connection-> "properties"
In the Local Area Connection properties, double-click the internal protocol (TCP/IP).
Set the IP address. It can be set manually. If the router turns on the DHCP function, it can also be set to automatically obtain the IP address and DNS server address, which can solve the problem of IP address conflict.
Second, the IP address used by the local computer is 192. 168. 1, which overlaps with the IP address of the router.
Because the default management address of the router is192.168.1.1,computers under the router cannot use this address, but can use192.168.1.2. In addition, if the IP address is fixed, you need to fill in the DNS server address. You can contact the network provider. Of course, there is another way to automatically obtain the IP address, enter the CMD command, enter the ipconfig /all command to obtain the best DNS address, and then record it and fill it in. In addition, it can also be found in the dns server address encyclopedia of China Telecom/Netcom/Tietong.
IP address translation
Every host on the Internet has a unique IP address. The IP protocol uses this address to transfer information between hosts, which is the basis of Inter operation. The IP address is 32 bits in length (* * * has two 32 IP addresses), and it is divided into 4 segments, each with 8 bits, expressed by decimal digits, and each segment ranges from 0 to 255, and each segment is separated by a period. For example,159.226.1.1. IP address can be regarded as network identification number and host identification number, so IP address can be divided into two parts, one is network address and the other is host address. IP addresses are classified into categories A, B, C, D and E5, and the applicable types are: large-scale networks; Medium-sized network; Small network; Multiple destination addresses; Spare. Commonly used are b and C.
The IP address is just like our home address. If you want to write a letter to a person, you need to know his or her address so that the postman can deliver the letter. Computers send messages like postmen. It must know the unique "home address" to avoid sending the letter to the wrong person. It's just that our address is represented by words, while the address of the computer is represented by binary numbers.
As we all know, in telephone communication, telephone users are identified by telephone numbers. Similarly, in order to distinguish different computers in the network, computers need to be assigned a special networking number, that is, "IP address".
When an IP address is divided into two parts: the network number and the host number, the designer must decide how many bits each part contains. The number of digits of the network number directly determines the number of networks that can be allocated (calculation method 2 network number digits-2); The number of digits of the host number determines the maximum number of hosts in the network (calculation method 2 host number digits -2). However, because the network scale contained in the whole Internet may be relatively large or relatively small, the designer finally chose a flexible scheme: dividing the IP address space into different categories, and each category has a different network number and host number.
Assignment of IP address
TCP/IP protocol needs different settings for different networks, and each node generally needs an IP address, a subnet mask and a default gateway. However, Dynamic Host Configuration Protocol (DHCP) can automatically assign an IP address to the client, which can avoid errors and simplify the setting of TCP/IP protocol.
So, how do inter-domain networks allocate IP addresses? IP addresses on the Internet are managed by an organization called ICANN (International Corporation for Assigned Names and Numbers).
IP addresses are now assigned by ICANN (international domain and Assigned Numbers Authority).
Inter: responsible for the United States and other regions;
ENIC: responsible for Europe;
APNIC (Asia-Pacific NEORK Information Center): Users in China can apply to APNIC (for a fee).
PS: 1998, APNIC headquarters moved from Tokyo to Brisbane, Australia.
The organization responsible for assigning Class A IP addresses is ENIC.
The organization responsible for assigning Class B IP addresses in North America is InterNIC.
APNIC is responsible for the allocation of Asia-Pacific class B IP addresses.
How to resolve IP address conflict
IP address conflict resolution:
First, the IP address of the computer under the router is different from the IP address of the conflicting computer, which can be solved by changing the IP.
Right-click My Network Places->; "properties":
Pop up the network connection management window, and right-click Local Area Connection-> "properties"
In the Local Area Connection properties, double-click the internal protocol (TCP/IP).
Set the IP address. It can be set manually. If the router turns on the DHCP function, it can also be set to automatically obtain the IP address and DNS server address, which can solve the problem of IP address conflict.
Second, the IP address used by the local computer is 192. 168. 1, which overlaps with the IP address of the router. Because the default management address of the router is192.168.1.1,computers under the router cannot use this address, but can use192.168.1.2. In addition, if the IP address is fixed, you need to fill in the DNS server address. You can contact the network provider. Of course, there is another way to automatically obtain the IP address, enter the CMD command, enter the ipconfig /all command to obtain the best DNS address, and then record it and fill it in. In addition, it can also be found in the dns server address encyclopedia of China Telecom/Netcom/Tietong.
How to resolve IP address conflict
You can't use the network when the error "The computer detected that the IP address conflicts with the physical address of your network card" occurs during the use of the computer. If the information files of IP address and MAC address are established at the same time when network users access the network, strict management and registration system will be implemented for LAN customers from beginning to end, and information such as IP address, MAC address, uplink port, physical location and user identity of each user will be recorded in the database of network management.
If we know the MAC address of the illegal user, we can search from the administrator database. If we record the MAC address comprehensively, we can find the specific user information immediately, which will save us a lot of precious time and avoid the trouble of looking for a needle in a haystack. At the same time, for some applications, it is necessary to avoid using IP addresses to limit permissions. If it is restricted from the MAC address, it is relatively safer and can effectively prevent someone from stealing the IP address.
Solution of personal IP address conflict
1. If the operating system of your computer is windows 98.
Click Start → Run in the lower left corner, type: winipcfg, click OK, click Release All in the pop-up window, and then click Update All to solve the problem.
If you are prompted that you cannot update, you need to restart your computer.
2. If the operating system of the computer you are using is windows 2000 or windows XP.
Click start → run in the lower left corner, type ipconfig /release, click OK, click start → run here, type ipconfig /renew, and click OK to solve the problem.
Causes and solutions of IP address conflict in LAN
For intranet and extranet, when using TCP/IP protocol, each host must have an independent IP address, and the host with IP address can communicate with other hosts on the network. With the popularization of network applications, the number of network users has expanded rapidly. Due to static IP address assignment, IP address conflicts occur one after another. IP address conflicts have had a bad influence. First, the network client can't work normally. As long as there are conflicting machines on the network, when the power is turned on, the client will frequently be prompted with address conflicts: "If the security policy of an application on the network (such as access rights and access control) is based on the IP address, this illegal IP user will pose a serious threat to the security of the application system.
Analyze the reasons
Sometimes the problem can't be found in time, and it can only be revealed when the conflicting network customers are online at the same time, so it is quite hidden. There are several reasons for IP address conflicts.
1. Many users don't know TCP/IP, and don't know how to set IP address, subnet mask, default gateway and other parameters. Sometimes users don't get the information of the above parameters from the administrator, or modify the information unintentionally. 2. When the administrator or user sets parameters according to the above parameters provided by the administrator, the parameters are incorrectly entered due to errors; 3. During the maintenance and debugging of the client, the maintainer uses the temporary IP address. 4. Someone stole someone else's IP address.
solution
After receiving the conflict report, we first determine the VLAN where the conflict occurred. Through the vlan definition of IP planning and the conflicting IP address, find the network segment where the conflicting address is located. This is very important to successfully find the MAC address of the network card, because some network commands cannot be accessed across network segments.
One is to isolate the client from the network, so that computers with illegal IP addresses can run on the network, and network administrators can find ways to find them. Application network test commands include ping command and arp command. Using the ping command, assume that the conflicting IP address is10.119.40.40. In the msdos window, the command format is as follows, and the italicized part is the command result.
C:\ Widow \ > Ping10.119.40.40
Request timeout
10.119.40.40 reply: bytes = 32 time & lt 1 millisecond TTL= 128 omitted.
Ping this machine has two purposes. First of all, we need to know that the machine we are looking for is indeed on the network. Second, we need to know the MAC address of this machine's network card. So how do we know its MAC address? This requires the use of the second command arp:arp command can only be effectively used in a certain VLAN, which is an underlying protocol and cannot cross-route.
IP address conflict ~ How to solve it?
Right-click My Network Places, Properties, Right-click Local Area Connection, Properties, and double-click TCP/IP to change the last digit of IP, which is between 2 and 254.