问题：

[多选] 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 informatio