单项选择题
A. Aggregator
B. Local preference
C. Atomic aggregate
D. Multiple exit discriminator
单项选择题 PE1 has connections to VPN sites that are served by three remote PE routers. How many LSPs must be established to support 2547bis?（）
单项选择题 Which command clears the history of BGP damped routes?（）
单项选择题 Which well-known community prevents a BGP speaker from announcing the associated prefix to itsinternal peers?（）