How many usable hosts are available in a CIDR /25 network?

In a CIDR /25 network, the subnet mask allows for 25 bits to be used for the network portion, leaving 7 bits for the host portion of the address. To determine the total number of addresses available for hosts, you calculate 2 to the power of the number of host bits, which is 2^7. This results in 128 total addresses.

However, in any IP network, two addresses are reserved: one for the network itself and one for the broadcast address. Therefore, we subtract these two reserved addresses from the total. So, from 128 total addresses, subtracting the 2 reserved addresses gives 126 usable host addresses.

This calculation is a fundamental aspect of understanding IP addressing and subnetting, particularly in how networks allocate addresses for devices while reserving necessary addresses for network functions. Thus, the answer correctly indicates that there are 126 usable hosts in a CIDR /25 network.