【单选题】

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.