HTTP statusCode (status code) 200, 300, 400, 500 sequence

201-206 indicates that the server successfully processed the status code of the request, which indicates that the Web page can be accessed normally.
200 (success) The server has successfully processed the request. Typically, this indicates that the server provided the requested Web page.
201 (created) The request was successful and the server has created a new resource.
202 (accepted) the server has accepted the request, but it has not been processed.
203 (non-authoritative information) the server successfully processed the request, but returned information that might 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 requestor to reset the document view (for example, to clear the form contents to enter new content).
206 (partial) The server successfully processed a partial GET request.

300-3007 means: To complete the request, you need to proceed further. Typically, these status codes are always redirected.

300 (multiple choices) the server can perform a variety of actions depending on the request. The server can select an action based on the requester, or provide a list of actions to choose from.

301 (permanently moved) The requested page has been permanently moved to the new location. When the server returns this response, the requestor is automatically forwarded to the new location. You should use this code to inform the search engine that the spider Web page or website has been permanently moved to a new location.
302 (Temporary move) The server is currently responding to requests from a Web page in a different location, but the requestor should continue to use the original location for future requests. The requestor is automatically transferred to a different location. However, because the search engine will continue to crawl the original location and index it, you should not use this code to tell the search engine page or site has been moved.
303 (See other locations) The server returns this code when the requestor should make a separate GET request for a different location to retrieve the response. For all requests except the HEAD request, the server automatically goes to a different location.
304 (not modified) The requested webpage has not been modified since the last request. When the server returns this response, the Web page content is not returned.

If the page has not changed since the requestor last requested it, you should configure the server to return this response. Because the server can tell the search engine that the webpage has not changed since the last crawl, it saves bandwidth and overhead.

305 (using a proxy) the requestor can only use the proxy to access the requested Web page. If the server returns this response, the server also indicates which proxy the requestor should use.
307 (Temporary redirect) The server is currently responding to requests from a Web page in a different location, but the requestor should continue to use the original location for future requests. The requestor is automatically transferred to a different location. However, because the search engine will continue to crawl the original location and index it, you should not use this code to tell the search engine that a page or site has been moved.

A 4XXHTTP status code indicates a possible error in the request and interferes with the server's processing.

400 (Error request) The server does not understand the syntax of the request.

401 (authentication error) this page requires authorization. You may not want to include this page in the index.

403 (Forbidden) The server rejects the request.

404 (not found) The requested Web page was not found by the server. For example, this code is often returned for Web pages that do not exist on the server.

For example: HTTP://WWW.0631ABC.COM/20100AAAA, it will go to the 404 error page

405 (method Disabled) Disables the method specified in the request.

406 (not accepted) cannot use the requested content attribute to respond to the requested Web page.

407 (requires proxy authorization) This status code is similar to 401, but specifies that the requestor must authorize the use of the proxy. If the server returns this response, it also indicates that the requestor should use the proxy.

408 (Request timed out) A timeout occurred while the server was waiting for a request.

409 (conflict) The server has a conflict when it finishes the request. The server must include information about the conflict in the response. This code may be returned by the server in response to a PUT request that conflicts with the previous request, as well as a list of differences of two requests.

410 (Deleted) The server returns this response after the requested resource is permanently deleted. This code is similar to the 404 (not Found) code, but is sometimes used to replace the 404 code in cases where the resource existed before and now does not exist. If the resource has been permanently deleted, you should use 301 to specify a new location for the resource.

411 (requires valid length) The server does not accept requests that do not contain a valid Content-Length header field.

412 (precondition not met) the server does not meet one of the prerequisites set by the requestor in the request.

413 (Request entity too Large) The server cannot process the request because the request entity is too large to exceed the processing power of the server.

414 (The requested URI is too long) The requested URI (usually the URL) is too long for the server to process.

415 (Unsupported media type) The requested format is not supported by the requested page.

416 (Request scope does not meet the requirements) if the page cannot provide the requested range, the server returns this status code.

417 (unmet expectations) the server does not meet the requirements for the expected Request header field.

500 to 505 means that the server has an internal error while trying to process the request. These errors may be the error of the server itself, not the request.

500 (server internal error) the server encountered an error and could not complete the request.

501 (not yet implemented) the server does not have the capability to complete the request. For example, the server may return this code when the server does not recognize the request method.

502 (Error Gateway) The server received an invalid response from the upstream server as a gateway or proxy.

503 (Service Unavailable) the server is not currently available (due to overloading or downtime maintenance). Usually, this is just a temporary state.

504 (Gateway Timeout) The server acts as a gateway or proxy and does not receive requests from the upstream server in a timely manner.

505 (HTTP version not supported) the HTTP protocol version used in the request is not supported by the server.

HTTP statusCode (status code) 200, 300, 400, 500 sequence