Resolution of IP address conflict failure caused by dial-up adapter

Whether it's a laptop or a regular desktop computer, there are currently three ways to access the Internet, one of which is dial-up Internet access via a normal modem, which is rare, but in some computers with Windows 98 operating systems installed dial-up adapters are often installed automatically by the system, one is through the broadband "cat" broadband dial-up Internet access through the telephone line, the other is through the LAN access to direct access to the Internet network. However, if the same computer uses a variety of network access at the same time, Internet users in the future when setting TCP/IP parameters, it is easy to confuse the dial-up adapter and network adapter adapters, once the IP address of these adapters are set to the same, it will cause the computer IP address conflict problems, So that the Internet is not normal. Because this kind of network fault has a certain concealment, as a result, it often brings trouble to our network troubleshooting; This is not, this article is an IP address conflict failure, because the Internet users can not tell how they are through the Internet, and thus indiscriminately modify the adapter's IP address caused.

There is an older computer in the unit's finance office, and because of the need to use some old version of the financial software, the computer is installed with the Windows 98 operating system, and has not been updated and upgraded to the Windows XP operating system until now. The computer is currently connected directly to the unit's local area network through the network card, at the same time set a fixed static IP address, the usual access to the unit's internal network speed is not bad! However, recent Treasury colleagues found the author said that their old computer these two days can not access the unit's internal network, trouble I can give them an emergency. For the author, such as network management personnel, the fault is the task, the author apart, quickly with QI line tester, network line, Crystal Head and clamp pliers, and colleagues straight to the network failure scene. When I got to the Office of the Treasury Department, I opened the old computer can not surf the internet, and try to access the internal network of units, it is true that there is no access to the local area network; Due to the lack of access to the network factors are many, the author intends to first from the external network connection, to the cause of the possible factors that can not be

First, the author first uses the instrument at hand to test the network cable connectivity of the old computer, and the test results show that the interface between the network cable and the crystal head of the cable is no problem; Secondly, the author also observed the network card devices installed in the old computer. Through careful observation found that the operating status of the network card device signal is also normal, and in order to prevent the network card device itself has problems or the installation is not in place, the author opened the system's running dialog box, and in which the "ping 127.0.0.1" string command, It turns out that local addresses can also be ping smoothly, which at least proves that the NIC is not a problem in hardware, and that the driver installation of the NIC device is normal.

Secondly, in order to test whether the network parameters of the computer system caused the failure of Internet, the author also specially to find a normal Internet laptop, the computer connected to the financial department of the old computer network cable interface, and internal network access testing units, the results found that the Internet is very fast, This indicates that the financial department to the LAN computer room switch This network connection line must be normal communication (in front of the network cable with the cable, although the connectivity test results, the test result shows that the circuit is in a connected state, but the line connectivity does not prove that the line communication is normal, Because if the network connection cable Middle core wire is in the short connection state, the result which is tested by the line measuring instrument is also connected, but in fact the short network connection cable is unable to transmit the information normally. Obviously, the "culprit" that causes the old computer to be unable to surf the internet is mostly the old computer hardware or system problems, or the computer system's network parameters are not set correctly.

Considering that the system reacts normally when running other applications in the old computer system, the author estimates that the computer has no problem with the hardware, mostly because the network parameters are not set correctly or the network components of the system are damaged. To this end, the author next on the network parameters are believed to check; when checking the network parameters, click Start/Settings/network Connections, and then in the Network Connections List window that opens, right-click the Local Area Connection icon, and then execute the Properties command from the right-click menu that appears. Enter the local Area Connection Properties setting interface, click the General tab page in the interface, select the Internet Protocol (TCP/IP) item on the page, and then click the Properties button to open the TCP/IP Properties Settings dialog box. In this dialog box, the author carefully examines the computer's IP address and gateway address, the results found that everything is normal. Since the network parameter configuration of the computer is not a problem, is it really a problem with the computer system?

The old computer in the Treasury because of the installation of the Windows 98 operating system, the author carefully looked at the system during the boot process automatically loaded some program files, and currently running some of the applications, did not find any suspicious, And the author also with the help of the system testing procedures for the entire computer system file for a comprehensive check, the results did not find any flaws. The author is really anxious, because the financial department of the old computer installed with special software, can not arbitrarily reinstall the system, which forced the author must find the specific reasons not to go online. Under the helpless, the author intends to reassign the computer to a new IP address to see; According to this idea, the author quickly opened the local Connection property settings interface, and in which the corresponding network connection adapter "Internet Protocol (TCP/IP)", and then in tcp/ A new IP address has been replaced in the IP Properties Settings dialog box. and click the "OK" button in the Settings dialog box, and then the author opened the system's running dialog box, and ping the new IP address to ping test, the result found that the new IP address does not conflict with other addresses; The author in the old computer system in the network test, this time finally Vista, Internet speed is very fast.

Here, the author has found the old computer can not access the reason, that is, the computer's IP address and other address conflict, but this computer's IP address How can conflict, the author is still baffled, Because when the author looked at the same as the old computer in a subnet with the other workstation IP address, found that there is no IP address and the financial department of the old computer IP address the same, that this particular IP address conflict phenomenon is how to produce it?

Once again, I went to the local connection properties settings interface and checked each component item in the General tab page, and found that the Dial-up networking adapter was installed by default on the computer, and when I entered the TCP/IP Properties Settings dialog box for the Dial-up networking adapter, It turns out that the IP address of the adapter is exactly the same as the IP address of the network card.

As it turns out, the old computer in finance is installed with the Windows 98 operating system, which typically installs the Dial-up networking adapter by default, regardless of whether the computer is connected to a modem device, but the dial-up networking adapter generally does not need to allocate a single fixed IP address. You just need to use the default parameter configuration, and we don't need to configure it. Use the computer's financial office colleagues in the process of surfing the internet when the speed is not fast, they try to modify the network parameters, but he did not know what dial-up network adapters and network adapter adapters exactly what is used, and then on the dial-up network adapter parameters have been modified, This resulted in a conflict between the address of the network card and the address of the Dial-up network adapter, which eventually caused a failure of the old computer in the Finance Department to be unable to surf the internet. When I replace a new IP address for the NIC, the phenomenon of IP address conflict automatically disappears, so the old computer's internet speed is back to normal again.

Summing up the above troubleshooting process, I think that I did not realize that the existence of the dial-up adapter, will also "lure" IP address conflict, resulting in the process of troubleshooting network failure to take a detour! Considering that the current way of dialing through a normal modem is rare, Therefore, I suggest that in the future when the Internet is installed on the computer with Windows 98 operating system, it is best to remove the unused dial-up network adapter device, because its existence will not only "induce" the IP address conflict, but also affect the normal speed of the internet!