简答题

Drag and drop question. The upper gives the MPLS functions， the bottom describes the planes.
Drag the above items to the proper location at the below

A.Before MPLS is enabled， the ip cef command is only requited on routers 1 and 4
B.After MPLS is enabled， the ip cef command is only required on routers 1 and 4
C.Before MPLS is enabled， the ip cef command is only required on the Ethernet 0 interfaces ofrouters 1 and 4
D.After MPLS is enabled， the ip cef command is only required on the Ethernet 0 interfaces ofrouters 1 and 4
E.Before MPLS is enabled， the ip cef command must be applied to all provider routers

A.To prevent customers from running TDP with the ISP routers
B.To prevent customers from running LDP with the ISP routers
C.To prevent other ISPs from running LDP with the ISP routers
D.To prevent man-in-the-middle attacks
E.To use CBAC to shut down Distributed Denial of Service attacks
F.To use IPS to protect against session-replay attacks
G.None of the above

A.IKE keepalives are unidirectional and sent every ten seconds
B.IPsec uses the Encapsulating Security Protocol （ESP） or the Authentication Header （AH）protocol for exchanging keys
C.To establish IKE SA, main mode utilizes six packets while aggressive mode utilizes only threepackets
D.IKE uses the Diffie-Hellman algorithm to generate symmetrical keys to be used by IPsec peers