CISCO CCNA Exam – Q149

The network administrator needs to address seven LANs. RIP version 1 is the only routing protocol in use on the network and subnet 0 is not being used. What is the maximum number of usable IP addresses that can be supported on each LAN if the organization is using one class C address block?

A. 8
B. 6
C. 30
D. 32
E. 14
F. 16

Correct Answer: C

Since there is one class C network that means 256 total IP addresses. Since we need 7 LAN blocks and we cannot use the first one (subnet 0) we take 256/8=32 hosts.
However, since we need to reserve the network and broadcast addresses for each of these subnets, only 30 total IP addresses are usable.