network tool WHOIS for IP/URL validity testing

With all the Internet fraud that abounds today (phishing, dns cache poisioning, hijacking),
some tools are useful to ensure we get the 'real McCoy' when we go online.

Two are fundamental tools for validating a URL:

NSLOOKUP {domain_name or ip_address} will map a name->address and conversley.
If the site is playing by the rules, each will point to the other. Beware of any site
that will not map.
Linux, Macintosh, and Windows have this service supplied; just open the command prompt
and type-in your request.

WHOIS {domain_name or ip_address} is similar to nslookup but reports the official domain information when registered.
Linux and Macintosh supply this service. Windows users may wish to see the shareware at
http://www.softpedia.com/get/Network-Tools/Traceroute-Whois-Tools/Whois.shtml
(no, I'm not associated in any way).

For those with the Cygwin Unix emulator, whois is a component that can be loaded.