Ezonexam has a Class C network and you need ten subnets. You wish to have as many addresses available for hosts as possible. Which one of the following subnet masks should you use?

A．255.255.255.192

B．255.255.255.224

C．255.255.255.240

D．255.255.255.248

E．None of the above

参考答案

正确答案：C
解析：Explanation:Usingthe2n-2formula,wewillneedtouse4bitsforsubnetting,asthiswillprovidefor24-2=14subnets.Thesubnetmaskfor4bitsisthen255.255.255.240.IncorrectAnswers:A.Thiswillgiveusonly2bitsforthenetworkmask,whichwillprovideonly2networks.B.Thiswillgiveus3bitsforthenetworkmask,whichwillprovideforonly6networks.D.Thiswilluse5bitsforthenetworkmask,providing30networks.However,itwillprovideforonlyfor6hostaddressesineachnetwork,soCisabetterchoice.