How many addresses are in a /26?

• A. 32
• B. 64
• C. 128
• D. 256

Answer: (B)

In IPv4 subnetting, the number of addresses in a subnet is determined by the number of host bits, which is 32 minus the prefix length. For a /26, there are 6 host bits, so the subnet contains 2^6 = 64 addresses. Remember that one is the network address and one is the broadcast address, leaving 62 usable host addresses. The other options correspond to different prefixes: a /27 yields 32 addresses, a /25 yields 128, and a /24 yields 256.