[单选题]IP地址为：192.168.50.70，掩码为：255.255.255.248，则该IP地址所在子网的子网有效IP为（）

正确答案 ：C

192.168.50.65---192.168.50.70

[多选题]The Ezonexam network administrator issues the ping 192.168.2.5 command and successfully tests connectivity to a host that has been newly connected to the network. Which protocols were used during the test? (Choose two)

正确答案 ：AE

ARP

ICMP

解析：解析：Explanation:ARPfindsthehardwareaddressofahostfromaknownIPaddress.Here'showitworks:whenIPhasadatagramtosend,itmustinform.aNetworkAccessprotocol,suchasEthernetorTokenRing,ofthedestination'shardwareaddressonthelocalnetwork.(Ithasalreadybeeninformedbyupper-layerprotocolsofthedestination'sIPaddress.)IfIPdoesn'tfindthedestinationhost'shardwareaddressintheARPcache,itusesARPtofindthisinformation.ICMPworksattheNetworklayerandisusedbyIPformanydifferentservices.ICMPisamanagementprotocolandmessagingserviceproviderforIP.ItsmessagesarecarriedasIPdatagrams.RFC1256isanannextoICMP,whichaffordshosts'extendedcapabilityindiscoveringroutestogateways.Periodically,routeradvertisementsareannouncedoverthenetwork,reportingIPaddressesfortherouter'snetworkinterfaces.Hostslistenforthesenetworkinfomercialstoacquirerouteinformation.Aroutersolicitationisarequestforimmediateadvertisementsandmaybesentbyahostwhenitstartsup.

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