Q:

Identify Webserver & Script of a website

I have got two simple questions

How can I tell what server is a website on? I remember I used to read the HTTP Host Header to identify the type of server. Is there any tool to do it?

2a. A lot of the website have the page extension .html and you just know they are not html. How can I tell what programming language is behind them? 
2b. For ASPX, I think IIS can map the extension, so it will show HTML instead of ASPX, right?
Cheers

A:

1.
Yes, you can check the http header tag "SERVER". Example of responses:
-Microsoft-IIS/6.0
-GFE/1.3
-Server Apache/2.2.11 (Ubuntu) PHP/5.2.6-3ubuntu4.2 with Suhosin-Patch
You can also check "X-Powered-By" on some servers, example:
-PHP/5.2.6-3ubuntu4.2
-ASP.NET
You can do this in firefox/firebug for example. Go to NET pick a request, select headers and check under response headers. You could do this is Fiddler to or any other http sniffer.
2a)
See my first answer
2b)
Yes you can map .html or anything as a "asp.net" extension, meaning that the extension will be handled by the web application. Common use is that you have a httphandler that catches that extension in web.config. 
Not sure what your endgoal of these questions are.. or rather to what purpose, maybe we could answer better then.

