Http Header information & status code

Header Information

(status-line): status entry, including protocol type, HTTP return code and status;

Cache-control: Whether it can be cached (public can; private and no-cache; Max-age indicates that it can be cached for a long time)

Expires: Expiration time, priority is lower than max-age in Cache-control.

Last-modified: Last/Last modified time of the file.

Age: The time from the most recent cache-to-node moment to the moment when the request was initiated is long.

Connection: Whether to keep the connection after getting data (keep-alive: Keep the connection after obtaining, so that the next request can be initiated by reducing the time spent parsing and building, such as Timeout=28;close: Release the connection after the end of the data transfer, The next time you resolve the connection. ）

Date: The time that the file was generated from the server/last cache by the node; date + Max-age=expires

Content-encoding: Encoded format of the file (gzip, etc., indicates that it has been compressed)

Referer: The source of access for this URL content request.

Content-type: File types (text, pictures, aspx, etc.)

Content-location: The actual location where this URL content resides.

Etag: The file is uniquely identified. A label based on the header header information of a file, obtained by a mixed-order or hash algorithm. Once a file changes, the label must change.

Content-length: File Size

Server: Client device condition (server type and version)

X-powerd-by: scripting language.

HTTP status Code

Some of the common status codes are: 200-Server successfully returned to Web page 304-The webpage has not been modified since the last request, and the page content will not be returned. 404-The requested page does not exist 503-Service Not available

Detailed decomposition: A 1xx (temporary response) represents a temporary response and requires a status code for the requester to continue the operation. 2XX (Success) indicates the status code of the request was successfully processed. 3xx (redirect) indicates that further action is required to complete the request. Typically, these status codes are used for redirection. 4xx (Request error) These status codes indicate a possible error in the request and hinder the processing of the server. 5XX (server error) These status codes indicate 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.

Http Header information & status code