How do the Registrars Know if a Domain is Available or Taken

[lazukars]

I really would like to build my own domain name checker via PHP. Does anyone know how domain companies can tell if a domain is taken or available? Any help in this area would be greatly appreciated.

Sincerely,
Ryan

 

[weblord]

they use domain whois server to know that.
like this
http://network-tools.com/default.asp?prog=whois&host=namepros.com
you can know the whois server that served that info is
whois.internic.net:

 

[lazukars]

Ok. So Registrars get the domain info from the domain whois server, like whois.internic.net. However, can anyone use these servers to their will. Could I make thousands if not hundreds of thousands of requests to domain servers just like the domain registrars Godaddy and enom do? Thanks again.

Ryan

 

[weblord]

that i don't know i haven't reached that number of queries for i only run like 500 times a day whois using domain name analyzer
but i think it's public server
and as long as you can offer it to anyone with differing ip addresses.

a good read:
http://en.wikipedia.org/wiki/Whois

i think it can withstand millions or billions queries since that's their purpose.

there's a software i use called registry fusion which offers pricing on bulk whois for commercial purposes
http://hexillion.com/whois/pricing.htm

Ok. So Registrars get the domain info from the domain whois server, like whois.internic.net. However, can anyone use these servers to their will. Could I make thousands if not hundreds of thousands of requests to domain servers just like the domain registrars Godaddy and enom do? Thanks again.

Ryan

 

[DotWeekly]

The Registry. Each TLD has a registry and they are the main source.

Verisign for .com & .net etc.

You can do a search on Google like this: .com registry