What are the characteristics of the process of documenting the layers of an existing network? （）

A.begins with gathering organizational input that may be inaccurate

B.begins with gathering organizational input that does not need to be supplemented by a network audit

C.requires a network audit to support some upgrade decisions

D.requires a network audit to support any network restructuring

E.provides reliable input for verifying network consistency

F.does not provide reliable input for designing changes