多项选择题
Which three pre-conditions must be met before an OSPF router can perform graceful restart? （）
A. Router must be an ABR. B. Router must contain one sham link. C. The network topology must be stable. D. Router must be able to forward packets. E. Neighbors must support graceful restart.
单项选择题 Which Behavior Aggregate (BA) is used to classify traffic arriving on an LSP?（）
单项选择题 Which mechanism does External BGP use to prevent the formation of routing loops?（）
单项选择题 By default, which JUNOS software routing table contains IPv6 unicast routes?（）
