【 Weak current College 】 Unveils fixed IP addresses do not have access to the Internet puzzle

As the saying goes "big Woods, what bird has", when the LAN network size is growing, what kind of network failures are likely to occur. This does not, network-man had encountered such a strange symptom, it is the Office network, using a fixed IP address of your computer suddenly are normal on-line, while those who use the "auto-obtain address" form of the computer, but they are normal on-line. Because of this failure phenomenon causes are special, in order to help friends accumulation experience online, this article on this particular failure of meticulous elimination process execution interpretation, restore, looking forward to the public from the following content received inspiration!

Some hosts do not have access to the Internet

Because of the work required, network-man office a few computers that do not have access to a local area network, nor to seek the LAN direct access to the Internet network, and is resolved in the form of shared ADSL routers, dial-up connection to the city's e-government intranet, at the same time, all connected to the e-government intranet computer daily are not allowed to access Internet network, so as not to come from the Internet network of virus, Trojan horse attacks on e-government intranet. In order to facilitate maintenance, network, network staff then enabled ADSL router is equipped with DHCP services, and in which the address pool is configured, the parameters, Office experience testing all of the computers in the normal access to 192.168.0.10-192.168.0.50 this range of IP addresses, and to the normal execution of e-government intranet access.

Configured by the DHCP server parameters, any one client computer as long as it is configured to "auto-obtain IP address" form, it will be able to access municipal e-government intranet; however, there are two somewhat familiar with colleagues from the network knowledge, consider that the use of the dynamic address on the Internet, the system starts a slow, so they do claim that their computer Internet address changes into a static address, a colleague of his computer on the Internet address configuration into 192.168.0.16, another colleague of his computer on the Internet address configuration into 192.168.0.33. Daily, whether it is a static address form, still with dynamic address forms, all of the computers in the Office can successfully access to city e-government intranet content, data and Internet access speed is particularly fast. However, starting from a certain day, a strange phenomenon occurred in the Office network, part of the computer to normal Internet access, but also part of the computer does not have Internet access; experience on the scene of a careful investigation of failure, network maintenance personnel found that a big secret that the Internet correctly without exception, use dynamic addresses that appear on Internet failure of the computer, and the two use a fixed IP address of the computer.

Positioning fault location

For the above symptoms, network maintenance has its own identification, he considered that since the use of dynamic address computer to the Internet, it indicates that the Office network ADSL router work status is normal, otherwise these computers can connect to the Internet can not be obtained from the DHCP server where the effective Internet parameters, so that queries are out on the failed computer system itself? network maintenance in the minds of the first Flash of a failed computer there may be a network viruses, because failure to function until the computer is connected to the Internet and other computers in the Office on the Internet status are quite normal, but the failed computer out of the question, so network viruses are very suspicious nature, after all, many infected with a virus, what symptoms may appear. In order to confirm the network virus can not "innocent", network maintenance staff decides to start killing the virus, so he immediately got the newest version of the genuine anti-virus software, and patiently to perform the installation, the anti-virus operation, through a period of time, the virus checking some harvest, those who lurk on the failed computer system "corners" of the virus, have all been mercilessly "expelled", watching these are continuous finishing off network viruses, network maintenance for more than a heart, is the question really is who lurk in the shadows of the network virus provoked? but experience online testing, network maintenance personnel found that one has the virus failed computer, still cannot access the city's e-government intranet, and the symptom, and exactly the same, it is clear that the network before the virus is not a failed computer cannot access the e-government Intranet "murderer".

In proving the network virus "innocence," the network maintenance personnel had reluctantly will doubt the "blame" for the physical connection, after all, the physical connection is unexpectedly, chances are good. To worry about troubleshooting computer's network connection cable fault or short circuit occurs, the network maintenance staff specifically to a professional network cable tester, on the target network cable connectivity state implementation of the scene, the test found that two failed computer cables are not present connectivity failures. In order to prevent network cable ends of Crystal head and switch or computer contacts not secure, the network maintenance will be inserted into the switch and the network card on the Crystal head, see wing wings to from, then follow the correct key points about how it will be inserted into the RJ45 port, until the Exchange port or network equipment of lights flicker; however, network maintenance workers try to access your computer from the failures of e-government intranet, I found that access is still not successful, however at this point from the failed computer system, ping service end host IP address is normal, this indicates that the fault client system does not have access to the intranet of the fault and cable connectivity no contact.

It is the fault of client systems themselves questions? but on second thought, two client system at the same time the possibility of a doubt is not very big, doubt certainly still in the network cable and switch port; in order to exclude the possibility that network maintenance by using their own laptops, to temporarily override failure a client system, perform online tests, test results, let the network maintenance is special but penRemember this computer should be able to properly to the Internet. Compare notebook computer and fault client system for the Internet parameter, network maintenance, see the notebook computer is a dynamic address, and the failure of the client system is a fixed address, don't use a fixed IP address is really not normal Internet? network maintenance personnel to confirm Internet address configuration questions, try the troubleshooting client system's IP address is also configured to "auto", the results obtained address fails the client system can immediately, it appears that the normal online question is due to the IP address configured improperly provoked.

Get into the fault causes

Despite the failure of client system uses a dynamic address forms to normal Internet access, but network maintenance workers still confused, why use a static IP address before you, failure of client systems are able to successfully access to electronic government intranet content, and now maintain the original static address, but does not access the e-government intranet? this symptom, network maintenance workers perform a careful thought, in his view since the dynamic address to Internet access, a static address cannot be the Internet, it will not be the Office network DHCP server has changed, causing it to dynamically assign the IP address of the client computer with has changed, and that those who have been using a static address for the computer is its Internet address does not follow the changes appear to access the e-government intranet failure phenomenon? according to this analysis, network maintenance on the Office network performed a test to see if the internal network can be added to a DHCP server, or the original DHCP server has changed; the original DHCP server is ADSL router is equipped with, as this network maintenance staff is prepared to seek the Web form, remote login to ADSL router equipment background system, verify DHCP service configuration can be touched. However, the network maintenance open IE reader, enter the default use of ADSL router is equipped by the address "http://192.168.0.1", I found that the equipment in the background system page cannot be opened, what is? and notebook computer is a normal Internet? network maintenance staff and from other computers can access the client attempts to access the system, "and" http://192.168.0.1 did not succeed, and use the ping command can not be normal ping-address of the router, ADSL router is equipped by default use of the IP address be changed?, network maintenance staff interviewed several of the staff of the Office, they all said no ADSL router equipment had, in network maintenance McDowell, fresh from the field missions of another employee came when he understands that the symptoms immediately after his back for a single ADSL router equipment, previous to that one ADSL router equipment is already used in other locations.

Later, the network maintenance personnel found the new ADSL router equipment, using the default IP address has been changed to 192.168.1.1, the use of "http://192.168.1.1" address to your new ADSL router equipment background pages, network maintenance, see the router also enabled the DHCP service, but do not configure the address pool parameter. In this case, the DHCP server for Office networks all client systems to automatically assign the address of 192.168.1.0 network segment, while those who use a fixed IP address failed because the client system is 192.168.0.0 network segment, then use a fixed address for the client system is not online. When these failures client system uses a dynamic address, they can be obtained from the DHCP server where 192.168.1.0 network segment address, at which point they will not be able to access the e-government intranet failure naturally immediately dispersed.