Which three characteristics apply to IS - IS but not to OSPF?（）

• A、uses a default IOS metric of 10 on each interface
• B、uses an on - demand circuit to reduce the hello and LSA flooding across switched WAN li nks,such as ISDN
• C、uses a DIS and a backup DIS to present the psuedo - node on the LAN
• D、encapsulates PDUs directly into a data - link frame
• E、uses stubby areas to improve network scalability
• F、runs PRC (Partial Route Calculations) to calculate IP re achability information