What are two reasons a network administrator would use CDP (Choose two.)（）。

A.to verify the type of cable interconnecting two devices

B.to determine the status of network services on a remote device

C.to obtain VLAN information from directly connected switches

D.to verify Layer 2 connectivity between two devices when Layer 3 fails

E.to obtain the IP address of a connected device in order to telnet to the device

F.to determine the status of the routing protocols between directly connected routers