title: whois command is not recognized
body: <p>I have downloaded nmap. As far as I know, it supports the 'whois' tool. When I try to type the following: whois yahoo.com (as example). I got the following error: 
  'whois' is not recognized as an internal or external command, operable program or batch file. Can anyone tell me what I'm missing? Do I need to install something other than nmap itself?</p>