CCNA 里的计算题

题目

CCNA 里的计算题
The number of required host addresses for each subnet in a network is listed below.
Net A--6 hosts 10.1.1.0/29
Net B--14 hosts 10.1.1.32/28
Net C--33 hosts 10.1.1.64/26
Net D--126 hosts 10.1.1.128/25
This number includes the host address requirements for all router ports and hosts on that subnet.After all device and router port address assignments are determined,what will be the total number of unused host addresses available?

答案

选C 因为ABD在分配完主机地址后都只剩下2个地址,但是那2个地址分别做网络地址和广播地址,所以ABD都没余下可用的地址了 而C中可以有2的(32-26)次方主机号可以分配,也就是有64个.在分配完33个主机地址和网络地址和广播地址后还余下(64-35)=29个