What are two uRPF working modes？（）

A.SLA responder knows type of operation， the port used， and duration.
B.SLA responder inserts in and out timestamps in the packet payload.
C.SLA sender and responder use the IP SLA Control Protocol to communicate with each other before
D.SLA sender and responder communication can be encrypted.
E.SLA sender and responder communication can be authenticated with MD5.

A.opaque LSA （Type 8）
B.opaque LSA （Type 9）
C.link LSA （Type 1）
D.network LSA （Type 2）
E.opaque LSA （Type 10）

A.MPLS is required between the ASBRs.
B.ASBR must hold all routing information.
C.It is a scalable solution.
D.It is a simple solution.
E.MP-EBGP is used to exchange routes between ASBRs.