Hi,
There are two options by which you can do :
string[] computer_name = System.Net.Dns.GetHostEntry(Request.ServerVariables["remote_addr"]).HostName.Split(new Char[] { '.' });
txt_ipaddress.Text = strClientIP.ToString() + "[" + computer_name[0].ToString() +"]";
after getting IP you can store it in Database.
Thanks ,
Pawan