Common HTTP Codes
HTTP is the standard protocol, which is used to serve web applications over the browser like chrome, Firefox. It’s an Application layer protocol in the OSI Reference Model (Open System Interconnection) the main work of this layer is to transfer the data over the network and display the information or web application data in the browser.
When data web applications transferred by the network it contains much information with us information about the data packet,content-length,content-type and status codes also the web application has. The status code tells the result of the request.
The status codes have five types of groups, according to the status code first digit. There specific status codes are
1xx — Informational
The (100 Continue) status code gives the information that the initial part of a request has been received and has not yet been rejected by the server after that server sends a last response when requests have been fully received.
2xx — Success
The (200 OK) status code gives the information that the web application request is successfully accepted by the server and it sends the result of the response.
The (201 Created) status code gives the information that the request is fulfilled and some new resources are generated and it sends on the response.
3xx — Redirection
The (301 Moved Permanently) you should receive a 301 redirect any time you permanently replace one URL to another user will be permanently sent to the new URL. The new URL will usually replace the old URL in search result, and the old URL will eventually disappear link equity is passed from the old URL to the new URL.
The (302 Found) redirects are similar to 301 redirect but the link equity is not passed,URLs are not replaced in search results. There are very few situations when you should use a 302 redirect. Most of the time 302 redirects are a bad idea.
The (304 Not Modified) returned when a file is unchanged since it was last accessed on the server.
Browsers make a request with the “if-Modified-Since” header. If the file hasn’t been modified the request won’t be fulfilled, and the cached version of the file will be served.
4xx — Client Error
The (400 Bad Request) arises when clients give the invalid HTTP request.means the HTTP request that was sent to the server is invalid.
The (401 Unauthorized) that error comes when your login credentials weren’t valid. The server doesn’t know who you are, and wants you to try to login again or the user trying to access the resource has not been authenticated or has not been authenticated correctly.
The (403 Forbidden) error is more explicit than a 401 with a 403 the server knows who you are,but is explicitly telling you that you aren’t allowed to access whatever you’re trying to access.
The (404 Not Found) when the URL being requested was not found.it’s not true that all 404s are bad.if a user mistype a URL,they should be served a 404.
The (405 Method Not Allowed) error comes when the request does not fulfill the requirement of the methods like in the request of the web application the request goes in the PUT method and in response you get the error message 405 means that the request method is not supported at the server.
The (413 Request Entity Too Large) error indicates that the string submitted by the client or user is too large and the server can not handle it.
5xx — Server Error
The (500 Internal Server Error) status code, or internal server error means that server cannot process the request for an unknown reason, sometimes this code will appear when more specific 5xx errors are more appropriate.
The (502 Bad Gateway) status code, means that the server is a gateway or proxy server, and it is not receiving a valid response from the back-end servers that should actually fulfill the request.
The (503 Service Unavailable) normally indicates that, although the web server itself is functioning and can respond to requests, the application accessed via the server is not responding. You should verify whether this is the result of any action you have performed.
The (504 Bad Gateway Time) indicates that the server is a gateway or proxy server,, and it is not receiving a response from the back-end servers within the allowed time period.