Default vs Inner-tunnel concepts

Dear, I want to use eap with TLS authentication in Freeradius. At this moment, I've setup both default and inner.-tunnel files, and everything works OK. Am I right or do I have to use just inner-tunnel file? Please can you help me in this concept? Because I think if I have to use eap with TLS, I have to edit default and inner tunnel files, but maybe I'm wrong and I just have to edit inner-tunnel file and let default file as it comes from package installation. Special thanks, TOM