Dec 29, 2016 02:36 AM|Chris Zhao|LINK
A Web site can contain multiple virtual directories and subdirectories, and Web.config files may exist in each one. ASP.NET applications inherit settings from Web.config files at higher levels in the URL path. The only exception is if one of those
applications overrides the setting by means of its own lower Web.config file.
reference: https://msdn.microsoft.com/en-us/library/e8z01xdh.aspx#Robust Programming