多项选择题 Which three steps are used to configure IPv6 in JUNOS software?（）

多项选择题 Which three RP election mechanisms are available in a PIM-SM domain?（）

单项选择题 Routers A and B are connected with a point-to-point OC-3 interface. Each routers OC-3 interface is configured for both Level 1 and Level 2. The routers are configured in different areas. How many IS-IS adjacencies exist between the two routers?（）