subdomains on a domain. Can someone help me?

[onequestion]

Hi friends..

Is it possible to find subdomains on a domain. Can someone help me?

currently i'm using this code..

private static String GetSubDomain(URL url)             
    {
              String host = url.getHost().toString();
         Pattern p = Pattern.compile("[.]");
        String u[]=p.split(url.getAuthority());
        if (u.length > 2)
          {
            int lastIndex = host.lastIndexOf(".");
           int index = host.lastIndexOf(".", lastIndex - 1);
 
           return host.substring(0, index);
         }
             return null;
    }

but it is not working for some domains like http://www.mail.yahoo.co.in and http://www2.austin.cc.tx.us

Any help will be greatly appreciated.. thanks

[Plater]

What do you mean by "it doesn't work"? Does it "miss" sections of the url that should be listed.
What are you considering a domain and what a subdomain? When you get down to it, pretty much everything is a subdomain. thescripts is a subdomain of the .COM domain. And you can trace higher to the arpa domains and such too.