For a valid IPv4 subnet, what is the maximum number of hosts allowed in a subnet with a /24 prefix?

In an IPv4 network with a /24 prefix, the subnet mask is 255.255.255.0, which means that the first 24 bits of the IP address are used for the network part, and the remaining 8 bits are used for host addresses. The formula to calculate the number of usable host addresses within a subnet is (2^n - 2), where (n) is the number of bits available for hosts.

In this case, with 8 bits available for hosts, the calculation becomes (2^8 - 2). This results in (256 - 2 = 254) usable host addresses. The subtraction of 2 accounts for the network address (the first address in the range, which identifies the subnet) and the broadcast address (the last address in the range, used for broadcasting to all hosts on the subnet).

This understanding is critical for network design and management, ensuring there are enough addresses for hosts without waste due to reserved addresses. The choice stating 254 hosts is thus the correct answer.