Websites like reviews.gcoupon.com, whois.com, domaintools.com gives you all the information regarding a website like server location, registrant, expiring date all the other information. But I wonder from where these websites get all this information?
closed as off topic by Ignacio Vazquez-Abrams, surfasb, music2myear, Sathya♦ Dec 21 '11 at 12:41
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WHOIS database has two models
WHOIS database query can be done using command line based utilities.
Now a days, modern TCP/IP implementation comes with whois utility and you can perform query as below
Here is the domain name for which you want to perform whois query. You can use -h parameter to force program to use particular whois server but if you dont use it, program will find whois server automatically.
I can't be sure about what above mentioned sites use but I can say they maybe by executing shell command using PHP or whatever server-side language they may be using and format the response to display the specific details.