Some common status codes are:
Usual http status codes:
200 - the server successfully returns the webpage
404 - the requested webpage does not exist
503 - the server timed out
1xx (provisional response)
Status codes that indicate a provisional response and require the requester to proceed.
- 100 (Continue) The requester should continue to make the request. The server returns this code to indicate that it has received the first part of the request and is waiting for the rest.
- 101 (Switch protocol) The requester has requested the server to switch protocols, and the server has confirmed and is ready to switch.
2xx (success) A status code indicating that the request was successfully processed.
- 200 (Success) The server has successfully processed the request. Usually, this means that the server served the requested web page. If this status code is displayed for your robots.txt file, Googlebot has successfully retrieved the file.
- 201 (Created) The request was successful and the server created a new resource.
- 202 (Accepted) The server has accepted the request but has not yet processed it.
- 203 (Unauthorized Information) The server has successfully processed the request, but the returned information may have come from another source.
- 204 (No Content) The server successfully processed the request but did not return any content
- 205 (Reset Content) The server successfully processed the request, but did not return any content. Unlike the 204 response, this response requires the requester to reset the document view (eg, clear form content to enter new content).
- 206 (Partial Content) The server successfully processed part of the GET request.
3xx (Redirect) Further action is required to complete the request.
Typically, these status codes are used for redirection. Google recommends that you use no more than 5 redirects per request. You can use Webmaster Tools to see if Googlebot is having trouble crawling redirected pages. The Web Crawl page under Diagnostics lists URLs that Googlebot was unable to crawl due to redirect errors.
- 300 (Multiple options) For the request, the server can perform various operations. The server can choose an operation according to the requester (user agent), or provide a list of operations for the requester to choose.
- 301 (Moved Permanently) The requested webpage has permanently moved to a new location. When the server returns this response (a response to a GET or HEAD request), it automatically forwards the requester to the new location. You should use this code to tell Googlebot that a page or site has permanently moved to a new location.
- 302 (temporarily moved) The server currently responds to requests from web pages in different locations, but the requester should continue to use the original location to respond to future requests. This code is similar to the 301 code for GET and HEAD requests and automatically redirects the requester to a different location, but you should not use this code to tell Googlebot that a page or site has moved, as Googlebot will continue to crawl the original location and indexed.
- 303 (View Other Locations) The server returns this code when the requester should use separate GET requests for different locations to retrieve the response. For all requests except HEAD, the server automatically goes to other locations.
- 304 (Not Modified) The requested page has not been modified since the last request. When the server returns this response, no webpage content is returned. You should configure your server to return this response (known as an If-Modified-Since HTTP header) if the web page hasn't changed since the requester's last request. The server can save bandwidth and overhead by telling Googlebot that the page hasn't changed since the last time it was crawled. .
- 305 (Using Proxy) The requester can only use a proxy to access the requested web page. If the server returns this response, it also indicates that the requester should use a proxy.
- 307 (temporary redirection) The server currently responds to requests from web pages in different locations, but the requester should continue to use the original location to respond to future requests. This code is similar to a 301 code in response to GET and HEAD requests and automatically redirects the requester to a different location, but you should not use this code to tell Googlebot that a page or site has moved because Googlebot will continue to crawl the original location and indexed.
4xx (client request error)
These status codes indicate that something might have gone wrong with the request, preventing the server from processing it.
- 400 (Bad Request) The server does not understand the syntax of the request.
- 401 (Unauthorized) The request requires authentication. The server may return this response for web pages requested after login.
- 403 (Forbidden) The server rejected the request. If you see this status code when Googlebot tries to crawl valid pages on your site (you can see this on the Web Crawl page under Google Webmaster Tools Diagnostics), your server or host is probably rejecting the visited by Googlebot.
- 404 (Not Found) The server cannot find the requested web page.
For example, this code is often returned for web pages that do not exist on the server. If you don't have a robots.txt file on your site and you see this status code on the robots.txt page of the Diagnostics tab of Google Webmaster Tools, then this is the correct status code. However, if you have a robots.txt file and you see this status code, your robots.txt file may be named wrong or in the wrong location (it should be at the top-level domain called robots.txt). If you see this status code for URLs crawled by Googlebot (on the HTTP Errors page in the Diagnostics tab), it means that Googlebot may be following an invalid link (an old link or a mistyped link) from another page.
- 405 (Method Disabled) The method specified in the request is disabled.
- 406 (Not Accepted) Unable to respond to the requested webpage with the requested content characteristics.
- 407 (Proxy Authorization Required) This status code is similar to 401 (Unauthorized), but specifies that the requester should authorize the use of a proxy. If the server returns this response, it also indicates that the requester should use a proxy.
- 408 (Request Timeout) The server timed out while waiting for the request.
- 409 (Conflict) The server conflicted while completing the request. The server MUST include information about the conflict in the response. A server may return this code in response to a PUT request that conflicts with a previous request, along with a list of differences between the two requests.
- 410 (Deleted) If the requested resource has been permanently deleted, the server will return this response. This code is similar to the 404 (Not Found) code, but is sometimes used in place of the 404 code when the resource previously existed but does not now exist. If the resource has moved permanently, you should use 301 to specify the new location of the resource.
- 411 (Valid Length Required) The server does not accept requests without a Valid Content-Length header field.
- 412 (Precondition not met) The server did not meet one of the preconditions set by the requester in the request.
- 413 (The request entity is too large) The server cannot process the request because the request entity is too large and exceeds the processing capacity of the server.
- 414 (The requested URI is too long) The requested URI (usually a URL) is too long for the server to handle.
- 415 (Unsupported Media Type) The requested format is not supported by the requested page.
- 416 (The requested range does not meet the requirements) If the page cannot provide the requested range, the server will return this status code.
- 417 (Expectation not met) The server did not meet the "Expectation" request header field.
5xx (server error)
These status codes indicate that the server encountered an internal error while processing the request. These errors may be an error with the server itself, rather than an error with the request.
- 500 (Internal Server Error) The server encountered an error and could not complete the request.
- 501 (not yet implemented) The server is not capable of fulfilling the request. For example, this code might be returned when the server does not recognize the request method.
- 502 (Bad Gateway) The server, acting as a gateway or proxy, received an invalid response from an upstream server.
- 503 (Service Unavailable) The server is currently unavailable (due to overloading or down for maintenance). Usually, this is only a temporary state.
- 504 (Gateway Timeout) The server acts as a gateway or proxy, but did not receive the request from the upstream server in time.
- 505 (HTTP version not supported) The server does not support the HTTP protocol version used in the request.
Attach a common picture of http:
