What are the basic configuration steps to enable IS - IS?（）
- A Configure the net system - id command under routerisis and enable IS - IS on each interface with the ip router isis command.
- B Configure the net sy stem - id and the network net - id commands under routerisis.
- C Configure the network net - id command(s) under routerisis and enable IS - IS on each interface with the ip router isis command.
- D Configure the network net - id command(s) and the is - type level -1- 2 command under routerisis.
- E Configure the net system - id and the network net - id commands under routerisis and enable ISIS on each interface with the ip router isis command.