Most if not all web hosting services allow users to link two or more domain names to the same account to save them the cost of a new account for each domain name. With such accounts, opening any of the registered domain names calls the same default page as the other. The solution is to write a Response.Redirect() call in the default page (usually Default.aspx) to redirect the user depending on the domain name entered.
The server variable SERVER_NAME contains the domain name part of the URL, so if the user entered 'http://example.com/folder1/default.aspx' its content will be 'example.com', and if the user entered 'http://www.example.com/folder1/default.aspx' its content will be 'www.example.com'. To check for both versions always use the String object's Contains() method, instead of checking for equality.
protected void Page_Load(object sender, EventArgs e)
{
string domainName = Request.ServerVariables["SERVER_NAME"].ToString();
domainName = domainName.ToLower();
if (domainName.Contains("example.com"))
{
Response.Redirect("~/dotcom.aspx");
}
if (domainName.Contains("example.net"))
{
Response.Redirect("~/dotnet.aspx");
}
}