Uri address = new Uri(HttpContext.Current.Request.Url.AbsoluteUri);
			if (address.Segments[0] == "Admin") //do something...

string path = HttpContext.Current.Request.Url.AbsolutePath;
// /TESTERS/Default6.aspx

string host = HttpContext.Current.Request.Url.Host;
// localhost

Uri address = new Uri(HttpContext.Current.Request.Url.AbsoluteUri);
			if (address.Segments[0] == "Admin") //do something...

Uri address = new Uri(HttpContext.Current.Request.Url.AbsoluteUri);
			if (address.Segments[0] == "Admin")

Segments is a zero based array that starts with the first segment.

Get Current URL and Segments. Also, get host or path.

C#