Perfect way to get Client IP Address in Asp.Net

Getting visitor IP is very frequent requirement in Web Development. There are many confusion about the method to get IP in best way. First of all be aware not to use System.Net.Dns.GetHostAddresses(strHostName) method because it will always return IP Address of the local machine on which Application is running. Use the following function to get IP Address

string clientIP;
string ip = Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (!string.IsNullOrEmpty(ip))
{
string[] ipRange = ip.Trim().Split(',');
int le = ipRange.Length - 1;
clientIP = ipRange[le];
}
else
clientIP = Request.ServerVariables["REMOTE_ADDR"];

First check HTTP_X_FORWARDED_FOR. It will give IP address of the client machine if client is using proxy server and if its null then read the IP address from Header.
Currently these are the only options available in Asp.Net. and they mostly work fine.

Note:Some times if NAT is enabled on Web server there are cases when It always pick local IP no matter what method you use. Check of NAT (Network Address Translation) for further information.
Hope this will help :). Any Suggestion, Correction and Updation is welcomed.