Alcatel-Lucent 4A0-105 問題集

質問 1：
Why should you configure send-flush-on failure on your PE routers when using active/standby pseudowires?
A. On failure, the PE sends an LDP flush-all-from-me message to all PE devices in the VPLS. This speeds convergence to the new topology.
B. It flushes the local FDB speeding recovery
C. It discards all packets in the queue and sends icmp-discad messages to the sender. The packets are re-transmitted resulting in no loss of data.
D. It is not important to use send-flush-on-failure as Active/Standby signalling automatically converges the FDB in all VPLS instances
正解：A

質問 2：
In RSTP,which state do all ports initialize in?
A. Forwarding
B. Discarding
C. Designated
D. Listening
E. Root
正解：B

質問 3：
When a PE node receives a PBB encapsulated frame on a B-VPLS, how does the PE determine which l-VPLS it belongs to?
A. When the B-MAC header is stripped the customer MAC address is then looked up in the FDB
B. The l-SID in the l-TAG is inspected to determine where the frame should be delivered.
C. The l-TAG in the l-SID is inspected to determine where the frame should be delivered.
D. The PE inspects the service label in the MPLS header before stripping the B-MAC
header.
正解：B

質問 4：
How is MAC learning achieved in traditional Ethernet switches?
A. As frames leave the switch, the SA is populated into the FDB.
B. As frames enter the switch, the SA is populated into the FDB.
C. As frames enter the switch, the DA is populated into the FD
D. As frames leave the switch, the DA is populated into the FDB.
正解：B

質問 5：
Click on the exhibit below.

Which bridge will become the root bridge?
A. Bridge E
B. Bridge D
C. Bridge C
D. Bridge B
正解：A

質問 6：
When ports configured with IEEE 802.3ah EFM are operationally down, what must the device do before declaring the ports are up?
A. The device will try to force the other side up using the evaluating flag in the PDU.
B. The device will detect the port change and will wait for normal operation mode.
C. The device will detectthe port change and revert to discovery mode.
D. The device will wait for the trasmit-interval of 5 before trying to rediscover the neighbor.
正解：C

質問 7：
In IEEE 802.1ag,which two key functions are configured on bridge ports (SAPs and SDPs) to support CFM messages? (Choose 2)
A. MUP
B. MAP
C. MEP
D. MIP
正解：C,D

質問 8：
The "discard-unknown" command has been enabled at the VPLS level. Which of the following statements is true? (Choose 2)
A. If the unicastSA has not been learned in the FDB,the frame will be dropped.
B. Broadcast traffic will be dropped.
C. If the unicast DA has not been learned in the FDB,the frame will be dropped.
D. All traffic will be dropped, including multicast and broadcast.
E. Broadcast traffic will be flooded.
正解：C,E

質問 9：
A router has just learned the 10th MAC address while the FDB size is also set to 10. What is the likely outcome?
A. The frame is always flooded
B. The frame is discarded if the destination is unknown.
C. The frame is dropped.
D. The frame is forwarded and MAC learning is automatically disabled.
E. More information is required to determine the fate of this new frame.
正解：D