Building a network is relatively easy, but managing the network is a tedious task. Not to mention the various requirements that the user has put forward to you will keep you busy, and the network failure is not enough to solve the problem, because there are too many reasons for the network to be unreasonable. However, as a network administrator, you don't have to lose the courage to solve the problem. As long as we regulate the fault phenomenon, there are still rules to follow.
First, the connection indicator does not light
Observe the two sides of the RJ45 on the back side of the network card. They are the connection status indicator and the signal transmission indicator. In the normal state, the connection status indicator is green and long, the signal indicator is red, and it should blink continuously. If we find the connection indicator, that is, the green light does not light, it means that the connection between the network card and the HUB or the switch is faulty. For this purpose, the tester can be used for segmentation. If the switch is connected to the network card through multiple modules, the binary method can be used for fast positioning. Under normal circumstances, most of the failures occur because the network cable is not securely connected and the inferior crystal head is used. Moreover, most of the fault points are problems at both ends of the connection, such as the port at the switch and the connector at the network card connected to the computer, and the tester can easily find the fault to solve.
Second, the signal indicator does not light
If the signal indicator is not lit, then there is no signal for transmission, but it is certain that the line is normal. Then try not to use the replacement method to change the network cable connecting the computer to another computer, or use the tester to check if there is signal transmission. If there is signal transmission, it is a problem with the local network card. The actual work experience proves that the NIC causes no information transmission is a common failure. In this case, you can first check whether the network card is installed properly and the IP settings are incorrect. You can try to ping the IP address of the machine. If you can ping, the network card is not too big. If it doesn't work, you can try to reinstall the NIC driver to solve it. In addition, for some NICs that use integrated NICs or low quality, it is prone to instability, that is, all settings are correct, but the network is unreasonable. The method of disabling the network card and then re-enabling it will also have an unexpected effect.
Third, the use of speed reduction
Many network cards are using 10M/100M adaptive network card, although the default setting of the network card is "adaptive", but due to the switch speed or the production method of the network cable, there may be some mismatch Case. At this time, don't try to set the NIC speed directly to 10M. The method is to right-click "Local Area Connection" to open its properties window, click the "Configure" button in the "General" tab, switch the open NIC Properties window to the "Advanced" tab, and select "In the Properties" list. Link Speed/Duplex Mode, select “10 FullMode” in the “Value” drop-down menu on the right, and click the “OK” button to save the settings.
Fourth, the firewall causes the network to pass through
In order to ensure security in the LAN, many friends have installed some firewalls. This can easily cause some "fake" faults, such as Ping can not access but can access the other party's computer, can not use the Internet but can use QQ. It is easy to determine if the fault is caused by a firewall. You only need to temporarily turn off the firewall and then check if the fault exists. The reason for this failure is also very simple. For example, when a user first uses IE to access a website, the firewall will ask whether to allow the program to access the network. Some users may not use such a setting because they are not allowed to do so. Naturally, the network is unreasonable. A more thorough solution is to remove this restriction in the firewall. For example, if I use Jinshan Net Dart, then I can open its window, switch to the "Apply Rules" tab, and then find the Internet Expler item in it, click "Allow".
V. The whole network is strange.
In the actual fault resolution process, for some larger networks, it is easy to have strange faults in the whole network. It’s strange because all the phenomena look normal, the lights and configuration are checked, there are no problems, but the network is nowhere; and even more impressive is the occasional one or two in the process of nowhere. The computer can be accessed intermittently. In fact, this is a typical network storm phenomenon, which occurs in some large and medium-sized networks. There are many viruses in the network, and then they are infected with each other. Because there are many computers in the network, the amount of data transmitted is very large, and the ports are directly occupied, so that normal data cannot be transmitted.
The most straightforward solution to this kind of virus-induced network storm is to find out the source of the storm. At this time, you only need to install a firewall on a computer in the network, such as Jinshan Net Dart. After you enable the firewall, you You will find the firewall keeps alerting. After opening, you can see the firewall intercepting the virus attack from the same IP address in the security log of the "Security Status" tab. At this time, you only need to find out which computer is based on the IP address. Disconnecting it from the network for virus detection and killing can generally solve the problem.
Tip: As a network administrator, even under normal circumstances, it is necessary to install a firewall such as Jinshan Net Dart to find out the source of the virus in the network and prevent it from further expanding. But the best way to avoid network storms is to subnet and install networked antivirus software. Subnetting, so that there are fewer computers in each subnet, so that even if the viruses spread each other, the amount of data generated is not large, and the entire network will not be compromised. The installation of the network version of anti-virus software can keep the entire network running smoothly.
Sixth, configuration error leads to network failure
The external performance of this fault is mostly the network indicator is normal, can also ping, sometimes can access intranet resources, but can not access the external network resources, and sometimes also show When visiting a website, you can only access it through an IP address, not through a domain name. This is caused by improper network configuration, that is, the correct network card and DNS are not set. If the gateway is set incorrectly, the computer can only be accessed inside the LAN. If the DNS is set incorrectly, it cannot be resolved when accessing the external website. To do this, we only need to open the properties window of the local connection, open the "Internet Protocol (TCP/IP)" property window, and then set the correct default gateway and DNS server address.
VII, Network Neighborhood can not access
The network is unimpeded, the connection with Interne or LAN is all normal, but the symptoms are not accessible when accessing other computers on the LAN through Network Neighborhood. There are many reasons for this kind of failure, and the author can provide a simple solution here. That is, directly access the shared folder on other computers in the network in the format of "computer name (IP address) share name" in the "Run" window, so that not only can this problem be bypassed, but also more than the access through the network neighborhood. Fast.
VIII. Group Policy Causes Network Failure
This kind of failure mainly exists between Windows2000/XP/2003 systems because Group Policy is set to prohibit access from the network. So we can enter "Gpedit.msc" in the "Run" window and press Enter. In the Open Group Policy window, select "Local Computer Policy - Computer Configuration - Windows Settings - Security Settings - Local Policies - User Rights Assignment". Then double-click "Reject access to this computer from the network" on the right, and select and delete the account list in the open window. ?
Network failure is a complex and variable fault, but as long as we master the essence, understand the steps of network construction, familiar with the easy-to-issue point of the fault, so that we can make the network unreasonable The problem.