What happens when a browser encounters a 302 header status code?

Question

Does the browser make a new request to the location given in the header?

I ask because I was playing around with Fiddler and noticed when I make a request to a page that returns a 302 HTTP code, there are two entries in the network log. The first is to the initial URL, and the second is to the new location given in the response header of the first request.

I'm just curious if web browsers work the same way, but just hide the first response from the user.

Answer 1

Yes, the browser works in very much similar fashion. You can try requesting a url in Chrome, possibly the one you tried in Fiddler. The Network Log of chrome would show you two requests.

The RFC description of HTTP status code can be read over here,

Quoting from there only, regarding the 302 status code:

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.

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When a server responds with a 302 status code, it send back the newer url (to which the current requested old url is to be redirected) to the requesting user-agent (likely a browser). Now, as per the RFC document, the user agent must not request the newer url for 302 status code. Yet most of them do make a second request.

Hope-this-helps.