Uri.IsLoopback returns true if the URI specified when this instance was created was 127.0.0.1, loopback, or localhost, or if the URI did not specify host information (for example, file:///c:Dir/file.txt). All other URIs return false.

The following example demonstrates the Uri.IsLoopback property.

using System;

public class UriTest {
 public static void Main() {
 Uri myUri = new Uri("http://127.0.0.1/index.htm", true);
 Console.WriteLine("{0} is loopback? {1}", myUri.ToString(), myUri.IsLoopback);

 myUri = new Uri("http://localhost/index.htm", true);
 Console.WriteLine("{0} is loopback? {1}", myUri.ToString(), myUri.IsLoopback);

 }
}

The output is

http://127.0.0.1/index.htm is loopback? True

http://localhost/index.htm is loopback? True