ourcompanyhasamainofficeandonebranchoffice.AllserversrunWindowsServer2003ServicePack2（SP2）.Themainofficehasathird-partygatewaydevicenamedGatewayGateway1isconnectedtotheinternalnetworkandtheInternet.Gateway1supportsIPSec.Inthebranchoffice，youhaveaservernamedServerYoucreateanIPSecpolicyonServerYouneedtoensurethatServer1canestablishanIPSectunneltoGatewayWhatshouldyouusetoconfiguretheIPSecpolicy？（）
A.anIPfilterthatallowsonlyInternetControlMessageProtocol（ICMP）traffic
B.anIPfilterthatallowsonlyTCPtrafficonport1701
C.apre-sharedkeyforauthentication
D.Kerberosauthentication
参考答案：C
