Get hosting environment

My friend asked:
What is easiest way to get to know about type of web server?

Why not with our age old friend 'telnet'?

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[harsha@JD11AF08 ~]$ telnet sriharsha.net 80
Trying 75.126.232.124...
Connected to sriharsha.net.
Escape character is '^]'.
GET / HTTP/1.1
Host: sriharsha.net

HTTP/1.1 200 OK
Date: Fri, 26 Dec 2008 16:36:23 GMT
Content-Length: 573
Content-Type: text/html
Content-Location: http://sriharsha.net/Default.htm
Last-Modified: Sat, 03 May 2008 10:52:12 GMT
Accept-Ranges: bytes
ETag: "72b52dbebadc81:20844d"
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET

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Same thing can also be obtained with HEAD
HEAD / HTTP/1.1
Host: sriharsha.net