Sometimes we must know what web server is running on a particular domain. Usually web hosts should be able to tell a client this, but if the client is afraid to ask, there is a way to ask the web server directly for this information.
Just to clarify: the web server is the process that serves files (HTML, PHP, ASP, images, etc) from a remote machine to your local web browser. The most likely choices in this day and age (2017) are Apache, NGINX or IIS. The latter is used by Windows servers, and the two former are used by Linux servers. There are other web servers too, such as lighttpd, but they’re used less commonly.
By asking the web server for this information, we can tell exactly who’s serving those files.
How to ask the Web Server
Let’s open a Terminal or Command Line Prompt window and utilise the good old fashioned Telnet protocol. Replace yourserver.com with the actual domain in question: