Error code:500 Internal Server error.

Problem background:

A previous site www.xxx.com was deployed on Windows Server 2008 Server A for a period of time, was deployed to the CentOS6.3 Server B, but the domain name has not changed, now encountered a problem, those URLs contain Chinese links are not open, prompted the following error:

Error code:500 Internal Server error. The request was rejected by the HTTP filter. Contact the server administrator. (12217)

Servers are deployed in the intranet, are through the Nginx Proxy server access to the LAN site, I use the intranet to access those URLs, you can access, the extranet is not, then I suspect that the problem is the proxy server, so, the situation reflected to the company's operation and maintenance engineers, he used the extranet to visit, found that can be accessed.

This is strange, according to the operation of the engineers years of experience, the following solutions are given:

In the DOS command box, enter the command "Ipconfig/flushdns".

Refresh page, successful access, problem solving.

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By the way, check the "Ipconfig/flushdns" Related information:

IPCONFIG/FLUSHDNS: Clears local DNS cache content;

The Ipconfig utility and its equivalent graphical user interface--windows 95/98 winipcfg can be used to display the setting values of the current TCP/IP configuration. This information is typically used to verify that manually configured TCP/IP settings are correct. However, if your computer and your local area network use a Dynamic Host Configuration Protocol (Configuration protocol,dhcp--windows NT, a protocol that assigns fewer IP addresses to more hosts), Similar to the dynamic IP assignment of dial-up Internet, the information displayed by this program may be more practical. At this point, Ipconfig can let you know if your computer is successfully leased to an IP address, and if so, you can find out what address it is currently assigned to. Understanding your computer's current IP address, subnet mask, and default gateway is actually a necessary project for testing and fault analysis.

The most common options

ipconfig--when using ipconfig with no parameter options, it displays the IP address, subnet mask, and default gateway value for each interface that is already configured.

ipconfig/all--when the all option is used, ipconfig can display the additional information (such as IP addresses) that it has configured for DNS and WINS servers and displays the physical address (MAC) that is built into the local network card. If the IP address is leased from a DHCP server, ipconfig displays the IP address of the DHCP server and the date on which the leased address is expected to expire (see other books about the DHCP server or ask about your webmaster).

Ipconfig/release and ipconfig/renew--This is a two additional option that can only function on a computer that leases its IP address to a DHCP server. If you enter Ipconfig/release, the leased IP address for all interfaces is then delivered to the DHCP server (the IP address is returned). If you enter Ipconfig/renew, the local computer tries to contact the DHCP server and leases an IP address. Please note that in most cases the NIC will be reset to the same IP address as previously given.

If you are using Windows 95/98, you should be more accustomed to using winipcfg instead of Ipconfig because it is a graphical user interface and displays the same information as Ipconfig, and also provides options for publishing and updating dynamic IP addresses. If you purchased Windows NT Resource Kit (NT resource bundle), Windows NT also contains a graphical alternative interface, the name of which is wntipcfg, similar to Windows 95/98 winipcfg.

Overview of the general parameters (you can also enter ipconfig/in DOS mode? for parameter query)

Ipconfig/all: Displays detailed information about native TCP/IP configuration;

IPCONFIG/RELEASE:DHCP client to manually release IP address;

IPCONFIG/RENEW:DHCP client to manually refresh the request to the server;

IPCONFIG/FLUSHDNS: Clears local DNS cache content;

Ipconfig/displaydns: Displays local DNS content;

The Ipconfig/registerdns:dns client registers with the server manually;

Ipconfig/showclassid: Displays the DHCP class information for the network adapter;

IPCONFIG/SETCLASSID: Set the DHCP class for the network adapter

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The operator was able to access it because he had not visited the site before, that is, there was no DNS cache information locally.

How to solve this problem automatically for other old users? Output header information? Which head?