IPSec VPN is a widely-acknowledged solution for enterprise network. What are the four steps tosetup an IPsec VPN？（）

A.The cypto isakmp keepalive command is used to configure the Stateful Switchover （SSO）protocol
B.Reverse Route Injection （RRI） is configured on at the remote site to inject the central sitenetworks
C.Each Hot Standby Routing Protocol （HSRP） standby group has two well-known MACaddresses and a virtual IP address
D.The cypto isakmp keepalive command is used to configure stateless failover

A.The crypto ACL number
B.The IPSEC mode （tunnel or transport）
C.The GRE tunnel interface IP address
D.The GRE tunnel source interface or IP address， and tunnel destination IP address
E.The MTU size of the GRE tunnel interface

A.A good security practice is to havethe none parameter configured as the final method used toensure that no other authentication method will be used
B.If a TACACS+ server is not available， then a user connecting via the console port would not beable to gain access since no other authentication method has been defined
C.If a TACACS+ server is not available， then the user Bob could be able to enter privileged modeas long as the proper enable password is entered
D.Theaaa new-model command forces the router to override every other authentication methodpreviously configured for the router lines
E.To increase security， group radius should be used instead of group tacacs+
F.Two authentication options are prescribed by the displayedaaa authentication command