Top 1000 Web Servers Survey Methodology
From July 2003 on, Port80 Software conducts periodic surveys of Fortune 1000 corporate Web sites to discover what type of Web server software they are running.
This survey is conducted between the first and fifteenth of a selected month and queries a list of 1000 leading global corporations' main corporate Web sites (e.g. www.corporation.com). Port80 Software queries this list of sites via a standard HTTP 1.1 GET request*, and the HTTP headers returned with the response are persisted. The value of the Server header from each response is then compared against well-known default values for popular commercial and open source HTTP servers to determine the identity of the server hosting the company's main Web domain.
By design, this method of categorization does not attempt to account for the possibility that the Server header, in particular cases, might have been altered to misrepresent the identity of the HTTP server (for example by means of a product such as ServerMask).
Real-time queries of the survey list or of any Web site using Port80 Software's "header check" tool may provide different results on Web server type from those published by Port80 Software.
* HTTP 1.0 GET requests were used for the January 2003-August 2003 Surveys, and HTTP 1.1 GET requests were used for all surveys after September 2003.