306 Switch Proxy

The HTTP 306 Switch Proxy status code is a reserved and unused status code from the HTTP/1.1 specification, intended to redirect a client to an alternate proxy for a specified period.

Table of Contents

Usage
Example
Code references
Takeaway
See also

Usage

The 306 Switch Proxy status code was designed for servers to respond when a client requests a resource through a proxy whose location has changed. The Set-Proxy header, proposed in the same expired Internet-Draft, specifies the new proxy location and the duration the address remains valid. Neither the status code nor the header was ever standardized.

Reserved

The IANA HTTP Status Code Registry lists this code as (Unused). "Switch Proxy" is the historical name from the expired draft (draft-cohen-http-305-306-responses). The HTTP specification reserves the code, and no current HTTP client or server implements the behavior.

Example

The following hypothetical exchange illustrates the behavior described in the expired draft. The client requests a resource through a proxy and receives a 306 Switch Proxy response directing traffic to an alternate proxy for 120 seconds. The Set-Proxy header was never standardized.

Request

GET /document.pdf HTTP/1.1
Host: proxy.example.re

Response

HTTP/1.1 306 Switch Proxy
Set-Proxy: SET; proxyURI="https://proxy-2.example.re:8080/" scope="http://", seconds=120

Code references

.NET

HttpStatusCode.Unused

Rails

:reserved

Symfony

Response::HTTP_RESERVED

Angular

@angular/common/http/HttpStatusCode.Unused

Takeaway

The 306 Switch Proxy status code is intended to instruct a client to use an alternative proxy for retrieving the requested resource. The status code remains reserved and is not implemented by current HTTP clients or servers.