Try this:
using System;
class Test
{
static void Main()
{
string[] urls =
{
@"http://g-ecx.images-amazon.com",
@"http://z-ecx.images-amazon.com",
@"http://ecx.images-amazon.com",
@"http://completion.amazon.com",
@"http://client-log.amazon.com",
@"http://www.amazon.com/184-8984226-0489751",
@"http://www.amazon.com/access",
@"http://www.amazon.com/gp/product/B0083PWAPW/ref=kin_dev_gw_dual_t/184-898422604...",
@"http://www.amazon.com/gp/product/B007OZNZG0/ref=kin_dev_gw_dual_c/184-8984226-04...",
@"http://www.amazon.com/gp/prime/signup/videos/ref=nav_menu_video_redirect_combine...",
@"http://www.amazon.com/gp/prime/signup/videos/ref=nav_menu_video_pic_redirect_com...",
@"http://www.amazon.com/gp/prime/signup/videos/ref=nav_menu_shipping_redirect_comb...",
@"http://www.amazon.com/gp/prime/signup/videos/ref=nav_menu_shipping_pic_redirect_..."
};
foreach(string url in urls)
{
Uri uri = new Uri(url);
string[] items = uri.Host.Split('.');
string domain = "";
if (items.Length == 3)
{
domain = items[1];
}
else if (items.Length == 2)
{
domain = items[0];
}
if (domain.IndexOf('-') > -1)
{
domain = domain.Substring(domain.LastIndexOf('-') + 1);
}
Console.WriteLine(domain);
}
Console.ReadKey();
}
}