How to read/write administration.config
IIS7 configuration system understands machine.config, web.config and applicationHost.config but does not handle administration.config natively. This means reading and writing administration.config is little difficult. If you use AhAdmin directly and call GetAdminSection for a section defined in administration.config, it will throw a configuration error for all configuration paths saying that it couldn’t find the section in the configuration file. Easiest way you can work with administration.config is by using Microsoft.Web.Administration (MWA).
Read full post at https://blogs.iis.net/ksingla/archive/2007/07/26/how-to-read-write-administration-config.aspx.
-Kanwal