What are two reasons a network administrator would use CDP? (Choose two.)（）
- Ato verify the type of cable interconnecting two devices
- Bto determine the status of network services on a remote device
- Cto obtain VLAN information from directly connected switches
- Dto verify Layer 2 connectivity between two devices when Layer 3 fails
- Eto obtain the IP address of a connected device in order to telnet to the device
- Fto determine the status of the routing protocols between directly connected router