Final answer:
To determine the number of usable IP addresses on a subnet, consider the subnet mask and subtract the network and broadcast addresses.
Step-by-step explanation:
In order to determine the number of usable IP addresses on a subnet, you need to consider the subnet mask. The subnet mask is a 32-bit value that determines the network and host portions of an IP address. It is represented by a series of 1s followed by 0s. The 0s in the subnet mask represent the host portion, while the 1s represent the network portion.
For example, let's say you have a subnet mask of 255.255.255.0. This means that the first three octets (24 bits) are dedicated to the network portion, and the last octet (8 bits) is dedicated to the host portion. Since each octet can have values from 0 to 255, there are 256 possible values for the host portion.
However, some IP addresses within a subnet are reserved for special purposes, such as the network address (the first address in the subnet) and the broadcast address (the last address in the subnet). These addresses cannot be assigned to individual hosts. So, the number of usable IP addresses is the total number of possible host addresses minus the network and broadcast addresses.