单项选择题
A.The source must send a PIM Register message to the rendezvous point （RP）
B.The source must first join the multicast group using IGMP before sending
C.The source must perform a Request to Send （RTS） and Clear to Send （CTS） handshake with the PIM designated router （DR）
D.No control plane signaling needs to be performed；the source can simply begin sending on the local subnet
单项选择题 TworoutersconfiguredtorunBGPhavebeenconnectedtoafirewall，oneontheinsideinterfaceandoneontheoutsideinterface.BGPhasbeenconfiguredsothetworoutersshouldpeer，includingthecorrectBGPsessionendpointaddressesandthecorrectBGPsessionhop-countlimit（EBGPmultihop）.WhatisagoodfirsttesttoseeifBGPwillworkacrossthefirewall？（）
单项选择题 Whiledeployinganewswitch，youaccidentlyconnectports3/12and3/18together，creatingaloop.STPdetecteditandplacedport3/18inblockingmode.WhydidSTPnotplaceport3/12inblockingmodeinstead？（）
单项选择题 Refer to the exhibit. This exhibit shows the NAT configuration for Router A and the output for a ping issued from device 171.68.200.48 and destined to 172.16.47.142. Based on this information, what change must be made to Router A in order for the ping to work?（）