单项选择题
You are running OSPF between two ERX Edge Routers across an OC-12c link with HDLC encapsulation. How many designated routers are present for this link?（）
A.0 B.1 C.2 D.3
单项选择题 What is the default authentication method on an OSPF interface?（）
多项选择题 What are the three OSPF authentication methods supported on the ERX Edge Router?（）
单项选择题 Where is OSPF authentication configured on the ERX Edge Router?（）
