Methods to troubleshoot network connectivity

It is relatively easy to build a network, but to manage the network is a relatively cumbersome work. And don't say the various requests that the user gives you will keep you busy, only the network does not pass this fault is enough trouble to solve, because the cause of the network is too many, as long as we will be the fault of the Regulation class, or have the law to follow, now the title of computer small set to you detailed explanation.

One, the connection led is not lit

Observe the back side of the network card with two LEDs on one side RJ45. They are the connection status LED and signal transmission led, where the normal status of the connection status indicator is green and long, the signal LED is red, normal should keep flashing. If we find the connection led, which means the green light is not lit, then the connection between the NIC and the hub or switch is faulty. This can be used to block the elimination of the tester, if from the switch to the network card through a plurality of modules interconnect, then you can use the two-point method for rapid positioning. In general, this failure occurs mostly because the network cable is not fastened, the use of inferior crystal is the first reason. And most of the fault points are connected at both ends of the problem, such as the switch port and connected to the computer network adapter at the connector, with the help of the tester can be very easy to find fault resolution.

Second, the signal led is not lit

If the signal LED is not lit, then there is no signal to transmit, but it is certain that the lines are normal between. Do not use the substitution method to swap the computer network cable to another computer to try, or use the tester to check whether there is signal transmission, if there is signal transmission then is the problem of the local network card. In the actual work experience proved that the NIC caused no information transmission is a more common fault. This can first check the network card installation is normal, IP settings are wrong, you can try to ping the IP address of this computer, if you can ping general instructions to explain the network card is not too big problem. If not, you can try to reinstall the network card driver to solve, in addition to some use the integrated network card or the quality of the network card, easy to appear unstable phenomenon, that is, all settings are correct, but the network does not pass. The method that can disable the NIC and then re-enable it will also have an unexpected effect.

Third, the use of spin down

Many network cards are used 10m/100m Adaptive network card, although the default setting of the network card is "adaptive", but by the switch speed or network cable production methods, may appear some mismatches. This time not to try to the network card speed directly set to 10M. The method is to open its Properties window by right-clicking Local Area Connection, clicking the Configure button on the General tab, switching the Open Network Card Properties window to the Advanced tab, and selecting Link Speed/duplex in the properties list mode, select "Ten Fullmode" in the Value drop-down menu on the right, and click OK to save the settings.

Four, the firewall causes the network to be impassability

In order to ensure security in the LAN, many friends have installed a number of firewalls. This is easy to cause some "false" fault, such as Ping impassability but can access each other's computer, can not access the Internet but use QQ. It is simple to judge whether the firewall is causing the failure, you only need to temporarily shut down the firewall and then check if the failure exists. The reason for this failure is also very simple, for example, when users first use IE to access a Web site, the firewall will ask whether the program to allow access to the network, some users because they are not careful to allow this will be used after such a setting, naturally lead to network impassability. A more thorough solution is to remove this restriction from the firewall. For example, the author uses Jinshan Dart, then you can open its window, switch to the "Apply Rules" tab, and then find out about Internet Explorer items, click "Allow".

Five, the whole network strange impassability

In the actual problem-solving process, for some larger networks are also prone to the entire network of strange faults. Said it strange, because all the phenomenon seems to be normal, led, configuration has been checked, no problem, but the network is not, but also more amazing is that in the process of the occasional one or two of computers can be intermittent access. In fact, this is the typical network storm phenomenon, more in some medium and large networks. There are many viruses in the network, and then between each other to carry out the infection, because the network of more computers, so the data transmission is very large, directly occupy the port, so that normal data can not be transmitted. For this virus-induced network storm solution is the most direct way to find the source of the storm, then only need to install a firewall on a computer in the network, such as Jinshan Network Dart, after the firewall you will find that the firewall non-stop alarm, open can be in the "security state" The security log of the label see Firewall blocking from the same IP address of the virus attack, then you just according to the IP address to find out which computer, it and network disconnect for virus killing, general can solve the problem.

Tips: As a network administrator, even under normal circumstances, it is necessary to install the firewall such as Jinshan Dart, to find out the network stream of the source of the virus, to prevent, to avoid further expansion of the harm. But the best way to avoid the network storm is to divide the subnet and install the Internet version of antivirus software. Divide the subnet, so that the computer within each subnet is relatively small, so that even if the virus spread, the amount of data produced is not a threat to the entire network, and the installation of the network version of anti-virus software can keep the entire network high-speed smooth operation.

Six, the configuration error causes the network to be impassability

The external performance of this fault is mostly the network indicator is normal, can also ping, and sometimes access to intranet resources, but can not access the extranet resources, and sometimes will show access to the site can only through the IP address, but not through the domain name access. This is the result of a typical improper network configuration, that is, the correct NIC and DNS are not set. If the gateway is set incorrectly, the computer can only be accessed within the LAN, and if the DNS settings are incorrect, the external Web site cannot be parsed. All we need to do is open the Properties window for the local connection, open the Internet Protocol (TCP/IP) Properties window, and then set the correct default gateway and DNS server address.

Seven, the Network Neighborhood cannot access

The network is unblocked, and the connection to the Interne or LAN is all right, but the symptoms that are inaccessible to other computers on the LAN through the Network Neighborhood. The cause of this failure is more, the author here can provide you with a simple solution. That is, you can access shared folders on other computers in the network directly in the format of the "Computer name (IP address) share name" in the Run window, which will not only bypass this failure, but also be quicker than accessing your network Neighborhood.

VIII. Group Policy leads to network impassability

This failure mainly exists between Windows 2000/xp/2003 Systems because Group Policy is set to prohibit access from the network. So we can enter "Gpedit.msc" in the Run window, select "Local Computer Policy-Computer Configuration-windows Settings-security Settings-Local policy-User rights assignment" in the Open Group Policy window, then double-click the "Deny access to this computer from the network" on the right side. , select and delete the list of accounts in the open window.

Network impassability is a complex and changeable fault, but as long as we grasp its essence, understand the steps of the network construction, familiar with the easy point of fault, so you can do status quo, easy to solve the problem of network impassability.