Proxy Web Servers and Authentication > How Proxies Work > Overview of HTTP/1.0 and HTTP/1.1 protocols

Listing of HTTP Response Codes

1xx: Informational

Request received, continuing process

2xx: Success

The action was successfully received, understood, and accepted

200 OK

3xx: Redirection

Further action must be taken in order to complete the request

301 Moved Permanently

304 Not Modified

305 Use Proxy

4xx: Client Error

The request contains bad syntax or cannot be fulfilled

401 Unauthorized

403 Forbidden

404 Not Found

407 Proxy Authentication Required

5xx: Server Error

The server failed to fulfill an apparently valid request

Adapted from RFC2616