These are interfaces for MC's DLNA services to ignore on the MC PC.
For example, I have several interfaces, an ethernet, a virtualbox interface, vpn, etc.
Say I want to ignore the virtualbox interface.
if I go to a cmd box on windows and do
ipconfig
I see amongst others a virtual box interface with an address of
192.168.0.1
and a netmask of 255.255.255.0
This translates to
192.168.0.1/24
in the interfaces to ignore list.