The HTTP status code in IIS 7.0, IIS 7.5, and IIS 8.0

This post describes the HTTP status codes that IIS 7.0, IIS 7.5, and IIS 8.0 use.

Every HTTP response contains a status code and, optionally, a reason phrase describing the status code. Status codes are fundamental to the HTTP protocol and are a standardized way of indicating common results.

Status codes are always three digits long and are grouped into five different classes, based on the first digit:

• 1xx—Information. Not often used, provides a general acknowledgment.
• 2xx—Success. The request was successfully handled and processed.
• 3xx—Redirection. The browser must follow the provided link, to allow the user to log in, for example.
• 4xx—Client error. There was a problem with the request. For example, the request sent invalid data, or the user isn’t authorized to perform the request.
• 5xx—Server error. There was a problem on the server that caused the request to fail.

1xx - Informational

These HTTP status codes indicate a provisional response. The client computer receives one or more 1xx responses before the client computer receives a regular response.

IIS 7.0, IIS 7.5, and IIS 8.0 use the following informational HTTP status codes:

• 100 - Continue.
• 101 - Switching protocols.

3xx - Redirection

These HTTP status codes indicate that the client browser must take more action to fulfill the request. For example, the client browser may have to request a different page on the server. Or, the client browser may have to repeat the request by using a proxy server.

IIS 7.0, IIS 7.5, and IIS 8.0 use the following redirection HTTP status codes:

• 301 - Moved permanently.
• 302 - Object moved.
• 304 - Not modified.
• 307 - Temporary redirect.