Finding the IP address of a domain

How can I find t开发者_StackOverflow中文版he IP address of an arbitrary domain? I want to get the IP address from the DNS server.

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require 'socket'
IPSocket::getaddress('www.google.com') #=> "74.125.79.147"

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Resolv is on a higher level than Socket, so will use more resources. However it has the ability to find all the ip addresses of a domain

require 'resolv'
Resolv.getaddresses("www.ruby-lang.org")

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Try going through the shell

domain = "google.com"
`host #{domain}`.match(/(\d{1,3}\.){3}\d{1,3}/).to_s
#=> "74.125.39.99"

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Try this code:

require 'resolv'
puts Resolv.getaddresses("www.panfu.dk") 

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you always can enter http://who.is/ and enter the url of the ip you're seeking for

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This is the java script code which will retrun the client's IP as json object

<script type="text/javascript">
function knowYourIP(json){
  document.write(json.ip); 
}

<script type="text/javascript" src="http://jsonip.appspot.com/?callback=knowYourIP"></script>