How to know that web server is Windows or Linux Based

1)Goto run->type CMD

IN CMD type
ping Target _Website_Name . Forexample- ping facebook.com
Now you will see several ping requests coming

Ping Google Server

We Are interested in seeing the TTL time which you can see at the end of each request in ping.
NOTE:-
1) If TTL <64 then the server is Linux based
2) If TTL>64 but <128 then the server is Windows bsaed
3) TTL>128 Mac and others.

From the above screenshot, it is clear that the servers of facebook are Mac and others

Note:- In some Cases you may not get ping replies ( Eg. you try it on your friend’s PC ). Now This can have two reasons, The server is down ie.. The machine is not connected to internet. Else the most common reason, The Firewall is protecting that PC and is not allowing your request to access that system