CompTIA N10-009 Exam - Topic 2 Question 38 Discussion

To support 75 hosts per subnet, you must choose a subnet size that provides at least 75 usable IP addresses. In IPv4, usable hosts per subnet equals 2^(host bits) 2 (subtracting network and broadcast). A /25 leaves 7 host bits (32--25 = 7), giving 2^7 2 = 128 2 = 126 usable hosts, which meets the requirement and is the smallest (most efficient) option listed that does so. A /26 leaves 6 host bits, giving 62 usable hosts, which is insufficient. A /27 gives 30 usable, and a /28 gives 14 usable, both far below 75. Network+ subnetting objectives emphasize selecting the smallest subnet that satisfies the host requirement to conserve address space while meeting growth and design constraints. Therefore, 192.168.13.0/25 is the most efficient option that accommodates at least 75 hosts per subnet.