A.BPDU guard can be used to prevent invalid BPDUs from propagating throughout the network. 
B.BPDU guard can guarantee proper selection of the root bridge.
C.BPDU guard can be utilized to prevent the switch from transmitteing BPDUs and incorrectly altering the root bridge election.
D.BPDU guard can be utilized along with PortFast to shut down ports when a switch is connected to the port.
E.None of the other alternatives apply

A.RTP traffic is exchanged between IP phone P1 and IP phone P2. IP phone P1 alerts the CCM of off-hook state. CCM instructs IP phone P1 to provide dialtone. IP phone P1 passes digits to CCM. CCM routes call to PSTN or IP phone P2.
B.CCM instructs IP phone P1 to provide dialtone. IP phone P1 alerts the CCM of off-hook state. IP phone P1 passes digits to CCM. CCM routes call to PSTN or IP phone P2. RTP traffic is exchanged between IP phone P1 and IP phone P2. 
C.CCM instructs IP phone P1 to provide dialtone.IP phone P1 alerts the CCM of off-hook state. IP phone P1 passes digits to CCM. RTP traffic is exchanged between IP phone P1 and IP phone P2. CCM routes call to PSTN or IP phone P2.
D.IP phone P1 alerts the CCM of off-hook state. CCM instructs IP phone P1 to provide dialtone. IP phone P1 passes digits to CCM. CCM routes call to PSTN or IP phone P2. RTP traffic is exchanged between IP phone P1 and IP phone P2.

A.The wireless client adapter will not be authenticated by the authentication server， but the access point deliver the packets to the intended receiver.
B.The wireless client adapter will not be able to send any packets to the access point.
C.The access point will discard the packets and never deliver them to the intended receiver.
D.The wireless client adapter will be authenticated by the authentication server and the access point will deliver the packets to the intended receiver.

A.Before the client adapter WEP key is generated， all wireless infrastructure devices （such as access points， servers， etc.） must be properly configured for LEAP authentication.
B.The client adapter WEP key should be generated by the AP and forwarded to the client adapter efore the client adapter can establish communication with the wireless network.
C.In infrastructure mode the client adapter WEP key must match the WEP key used by the access point. In ad hoc mode all client WEP keys within the wireless network must match each other.
D.The client adapter WEP key should be generated by the authentication server and forwarded to the client adapter before the client adapter can establish communication with the wireless network.
E.None of the other alternatives apply

A.to provide access to proprietary Cisco IOS software code in order to expand the number of vendors writing wireless code
B.to provide Cisco engineers with the opportunity to certify that any wireless devices that are made by third parties are compatible with Cisco wireless products
C.to provide customers with a broad range of WLAN client devices that have been tested for interoperability with Cisco Aironet innovations
D.to provide third parties with Cisco hardware in order to encourage the development of radical innovation in the area of wireless