C # query whois code

Using System;
Using System. Data;
Using System. configuration;
Using System. Web;
Using System. Web. Security;
Using System. Web. UI;
Using System. Web. UI. webcontrols;
Using System. Web. UI. webcontrols. webparts;
Using System. Web. UI. htmlcontrols;
Using System. net;
Using System. net. Sockets;
Using System. text;
Public Partial Class _ Default: system. Web. UI. Page
{
Protected   Void Page_load ( Object Sender, eventargs E)
{

}
Protected   Void Button#click ( Object Sender, eventargs E)
{
String_ R=Whois (textbox1.text. Trim ());

Response. Write (_ R. Replace ("\ R \ n","<Br>"));
}

/**/ ///   <Summary>
/// Domain name registration Query
///   </Summary>
///   <Param name = "Domain"> Enter the domain name, excluding WWW </Param>
///   <Returns> </returns>
Public   Static   String Whois ( String Domain)
{
If (Domain =   Null )
Throw   New Argumentnullexception ();
Int Ccstart = Domain. lastindexof ( " . " );
If (Ccstart <   0   | Ccstart = Domain. length)
Throw   New Argumentexception ();
String RET =   "" ;
Socket s =   Null ;
Try
{
String CC = Domain. substring (ccstart +   1 );
S =   New Socket (addressfamily. InterNetwork, sockettype. Stream, protocoltype. TCP );
S. Connect ( New Ipendpoint (DNS. Resolve (CC +   " .Whois-servers.net " ). Addresslist [ 0 ], 43 ));
S. Send (encoding. ASCII. getbytes (Domain +   " \ R \ n " ));
Byte [] Buffer =   New   Byte [ 1024 ];
Int Recv = S. Receive (buffer );
While (Recv >   0 )
{
RET+ =Encoding. ASCII. getstring (buffer,0, Recv );
Recv=S. Receive (buffer );
}
S. Shutdown (socketshutdown. Both );
}
Catch
{
Throw NewSocketexception ();
}
Finally
{
If(S! = Null)
S. Close ();
}
Return RET;
}
}