proxy settings in registry

Where Internet Explorer store proxy settings Tools -Internet
options -Connections -LAN settings -Proxy server.
Does it store it into registry? For example, I need test a big quantity of
proxy servers, some of them not work, etc. So, all this Address/Port information, which was filled into Address, Port fields will be stored in registry? So, then this unnecessary entries just litter registry. Or system clear this old settings from registry?

thanks