Redirection Code: 3xx

This class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request. The action required may be carried out by the user agent without interaction with the user if and only if the method used in the second request is get or head. A client should detect infinite redirection loops, since such loops generate network traffic for each redirection.

      Note: previous versions of this specification recommended a

      maximum of five redirections. Content developers should be aware

      that there might be clients that implement such a fixed

      limitation.

Multiple Choices: Code 300

The requested resource corresponds to any one of a set of representations, each with its own specific location, and agent- driven negotiation information (section 12) is being provided so that the user (or user agent) can select a preferred representation and redirect its request to that location.

Unless it was a head request, the response should include an entity containing a list of resource characteristics and location(s) from which the user or user agent can choose the one most appropriate. The entity format is specified by the media type given in the Content- Type header field. Depending upon the format and the capabilities of the user agent, selection of the most appropriate choice may be performed automatically. However, this specification does not define any standard for such automatic selection.

If the server has a preferred choice of representation, it should include the specific URI for that representation in the Location field; user agents may use the Location field value for automatic redirection. This response is cacheable unless indicated otherwise.

Moved Permanently: Code 301

The requested resource has been assigned a new permanent URI and any future references to this resource should use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the Request-URI to one or more of the new references returned by the server, where possible. This response is cacheable unless indicated otherwise.

The new permanent URI should be given by the Location field in the response. Unless the request method was head, the entity of the response should contain a short hypertext note with a hyperlink to the new URI(s).

If the 301 status code is received in response to a request other than get or head, the user agent must not automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which the request was issued.

      Note: When automatically redirecting a post request after

      receiving a 301 status code, some existing HTTP/1.0 user agents

      will erroneously change it into a get request.

Found: Code 302

The requested resource resides temporarily under a different URI. Since the redirection might be altered on occasion, the client should continue to use the Request-URI for future requests. This response is only cacheable if indicated by a Cache-Control or Expires header field.

The temporary URI should be given by the Location field in the response. Unless the request method was head, the entity of the response should contain a short hypertext note with a hyperlink to the new URI(s).

If the 302 status code is received in response to a request other than get or head, the user agent must not automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which the request was issued.

      Note: RFC 1945 and RFC 2068 specify that the client is not allowed

      to change the method on the redirected request.  However, most

      existing user agent implementations treat 302 as if it were a 303

      response, performing a get on the Location field-value regardless

      of the original request method. The status codes 303 and 307 have

      been added for servers that wish to make unambiguously clear which

      kind of reaction is expected of the client.

See Other: Code 303

The response to the request can be found under a different URI and should be retrieved using a GET method on that resource. This method exists primarily to allow the output of a POST-activated script to redirect the user agent to a selected resource. The new URI is not a substitute reference for the originally requested resource. The 303 response must not be cached, but the response to the second (redirected) request might be cacheable.

The different URI should be given by the Location field in the response. Unless the request method was head, the entity of the response should contain a short hypertext note with a hyperlink to the new URI(s).

      Note: Many pre-HTTP/1.1 user agents do not understand the 303

      status. When interoperability with such clients is a concern, the

      302 status code may be used instead, since most user agents react

      to a 302 response as described here for 303.

Not Modified: Code 304

If the client has performed a conditional GET request and access is allowed, but the document has not been modified, the server should respond with this status code. The 304 response MUST NOT contain a message-body, and thus is always terminated by the first empty line after the header fields.

Use Proxy: Code 305

The requested resource MUST be accessed through the proxy given by the Location field. The Location field gives the URI of the proxy. The recipient is expected to repeat this single request via the proxy. 305 responses MUST only be generated by origin servers.

      Note: RFC 2068 was not clear that 305 was intended to redirect a

      single request, and to be generated by origin servers only.  Not

      observing these limitations has significant security consequences.

Temporary Redirect: Code 307

The requested resource resides temporarily under a different URI. Since the redirection may be altered on occasion, the client should continue to use the Request-URI for future requests. This response is only cacheable if indicated by a Cache-Control or Expires header field.

The temporary URI should be given by the Location field in the response. Unless the request method was HEAD, the entity of the response should contain a short hypertext note with a hyperlink to the new URI(s) , since many pre-HTTP/1.1 user agents do not understand the 307 status. Therefore, the note should contain the information necessary for a user to repeat the original request on the new URI.

If the 307 status code is received in response to a request other than GET or HEAD, the user agent must not automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which the request was issued.