Page 404 Error What do you mean?

For the Internet family, I believe that you often visit certain pages, some pages will be inaccessible, prompted: 404 Not Found. Many Web pages may feel 404 Not Found is the page is not found or has been deleted. But if you're still stuck on all the pages that can't be accessed are called "404 Not Found", then you need to update your knowledge base.

What does 404 Not found mean?

The official name of "404" in "404 Not Found" is the HTTP status code (HTTP state code), which is used to represent the response state of the Web server HTTP.

Normal Web page can open, the response of the HTTP status code is: 200, we can see through a number of web testing software, such as the use of 17CE or Qiyun test tool online detection www.pc841.com speed, you can see the large HTTP status code, as shown in the figure below.

There are many HTTP status codes, usually 3-digit code, the first bit representing the state of the response, divided into 5 states, from 1xx to 5xx, respectively, representing the Web page response to continue processing, success, redirection, client error, and server errors.

Of these, 404 refers to a request failure, and the requested resource is not found on the server. As for what has not been discovered, you may need to further query, such as the server deleted the page address path changes, resulting in a non-normal access. For example, Pepsi Net recent revision, a lot of pages lost, if you visit the original page, will enter the 404 Hint page, as shown in the figure below.

So, you might ask, what does it show when you visit a non-existent website like Twitter or Facebook? Normally, what we're saying is that the error 502, 504, or 500 is displayed on the page.

Internal Server error means that the server encountered an unexpected condition that caused it to fail to complete the processing of the request.

502 Bad gateway refers to an invalid response received from the upstream server when a server acting as a gateway or agent attempts to execute a request.

504 Gateway timeout means that when a server acting as a gateway or agent attempts to execute a request, it fails to receive a response from the upstream server (the server that the URI identifies, such as HTTP, FTP, LDAP), or the secondary server (such as DNS).

Do not understand, it doesn't matter, remember a word can: 404 Not Found refers to the site is not what, but the page does not exist or can not be normal access caused, if a page can not open, but not open to the state, the use of Qiyun testing tools, test to see.