Rookie must read two examples of network failure _ Web surfing

Recently, the author in the school network maintenance process encountered two examples are not common network fault, but very interesting, feel the need to take them out for everyone's reference.

First failure: Client does not automatically obtain its TCP/IP configuration from the DHCP server immediately

Our school's IP addresses, DNS, and gateways are automatically obtained through the DHCP server. Some time ago, the school leaders feel that through the education of the city network speed is not fast enough, decided to direct the Internet through the telecommunications line, so I modified the DNS settings of the DHCP server, and the DHCP server restart. After a few teachers to me that their computer can not open the Web page, but QQ could be on. After I ruled out the virus and the system, I thought of the DNS problem.

Run the "ipconfig/all" command a check, sure enough, the machine's DNS display or the previous address, it was not in time to obtain updates from the DHCP server. This is simple, run the "IPCONFIG/RELEASW" command to release, and then run "ipconfig/renew" reconfiguration. The wonderful web page is in front of us again.

The second failure: the client's ARP cache table corresponds to the proxy server's MAC address error

A few machines in the school have a strange network fault: The machine can ping other machines, but it is ping the proxy server address (that is, the address of the gateway) 192.168.0.1, resulting in the machine can not access the Internet.

Run the "arp-a" command to view the current ARP entry, but found that the host address 192.168.0.1 corresponding MAC address is 00-00-00-00-00-00, this is not the host's MAC address Ah! Run the arp-a 192.168.0.1 00-06-29-EE-08-BF (correct MAC address) command, add an entry in the ARP cache, associate the IP address with the correct physical address, find that the problem is resolved, the computer can ping the host, and the Internet is normal.

We know that ARP (address Reverse Protocol, addressing Resolution Protocol) is used to display or modify the use of the Ethernet IP or Token Ring Physical address translation table. There is an ARP cache table in each computer with TCP/IP protocol installed, and the IP address is one by one corresponding to the MAC address, and the host's IP address to the MAC address is always in the ARP cache table. However, due to the system for some reasons, resulting in the ARP cache table host MAC address can not be updated to obtain, it caused the machine can not ping the host and can not access the Internet.